KT?!

. a,
M

sodium

“V’fié ’
I“ g . -
:2:ch Ema
‘atf‘ ‘ ~34 1'.

- N VN" ‘l ' C‘Sr.‘

m 1.;
«a. 2 '«VM
. > .Nzx- ..

un‘; 45".;

._ 4-.
~

M»
.m

"3":“h
"3:3 .\'
..

 

5

’,

was fan-f flaw“;
ipbifima 1‘ I rm”; EMT-s .fi

8W

lay a

’4‘?

6‘21; v
”:—¢‘r.:“~:”~-~"': ~
~ ‘ r. . fl
.p _ w- m
.335“:><'P:.?.‘1--w«»~, _,
“w; .. p. ”.1. ,M.,:._:,,”‘.
w . .. w __ ,.., u,~.r,v:v.;.;’r:::.:v “wh—m —
"‘5'; ~.".v:.':3..~~ *flc- w. fig“. 7.: .313...
. n... ... "-1 . V,” , .,
" Mm_‘m;z.~_ “Ti"— ? ...,. ' *"m ~at“ u: ' Mt: L“:
4‘ l ' u-n—o- ..__. Lv-
‘ » .~ ”Jr-'3. “'3‘ ~9"‘1""'...» m:L"m... 7":
‘ Ww‘r— ., .... ’19,
....._ ‘

"' «a

 

.v
w. ,. .
w ,
$*‘2:'§35 ‘ ‘3 "'” - ._‘ 333';er
" a , _ f {H W In.»

 

 

 

k UBRARY
Michigan State
University

“a...”

PLACE ll RETURN BOX to roman this chockou! from your record.
0 A D FINES rotum on Of bdoro data duo.

 

r———————_—'—_—_—
DATE DUE DATE DUE DATE DUE

I I
I ILJ ILJ
I I____ I I
° IL II J

I:__I

1 IV
___L__[::]
I——_'—I——_I

MSUIO AnAfflmdMAcflon/Equfl Olpponunlty Institution

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

man?”

/

This is to certify that the /

/
/

thesis entitled

Some Aspects of the Ecology of Naturally
Occurring Populations of Submerged
Vascular Hydrophytes in Municipal
Wastewater lagoons
presented by

Dennis P. Tierney

has been accepted towards fulfillment
of the requirements for

Ph.D. Fisheries 8: Wildlife

degree in

 

 

4%MLWMQUH

Majo: ptofesm”

 

November 8 , 1972

 

I Date

! 0-7839

 

© 1973
DENNIS PATRICK ‘TIERNEY

ALL RIGHTS RESERVED

ABSTRACT

SOME ASPECTS OF THE ECOLOGY OF NATURALLY OCCURRING
POPULATIONS OF SUBMERGED VASCULAR HYDROPHYTES IN
MUNICIPAL WASTEWATER LAGOONS I. PRIMARY
PRODUCTION AND PHOSPHORUS--NITROGEN

ACCUMULATION II. TRACE ELEMENT
ACCUMULATION III. POTENTIAL USE
AS A FEEDSTUFF AND A SOIL
CONDITIONER

By

Dennis P. Tierney

Primary production of Elodea canadensis and

 

Ceratophyllum demersum was determined for naturally occur-
ring populations collected from Fowlerville and Belding
sewage ponds and an urban catchment pond in Lansing,
Michigan. Plants were studied from late May to early
November, 1970. The relative intensity of environmental
resistance to plant growth was assessed for the habitats.
Simultaneously, the tissue accrual of phosphorus, nitrogen
and eight inorganic elements were quantitatively determined
(Co, Cd, Ni, Pb, Cu, Zn, Fe, Mn).

The relative intensity of environmental resistance
of the ponds was attributed to the different chemical

regimes. Plant growth was observed over analogous periods

Dennis P. Tierney

of the growth curve for E. canadensis in the Fowlerville

 

wastewater pond and the catchment pond and the comparative
growth rates were assessed. The measure used was doubling
time (DT) on a dry weight/square meter basis. The DT of

E. canadensis growing in the wastewater pond was ~4-fold

 

faster than populations existing in the catchment site.
Primary production and productivity measurements produced
the Opposite conclusions. Where both species coexisted,

E. canadensis exhibited biomass dominance. The largest

 

maximum standing crop of 410 gm dry weight/m2 and primary
productivity of 6.9 gm dry weight/mz/day was observed in

E. canadensis growing in the catchment site. The differ-

 

ence has been attributed to a disparity in the sizes of
the initial biomass of the populations prior to the onset
of growth and a significantly greater shift in light and
water temperature in the Fowlerville wastewater habitat
prior to the achievement of maximum standing crop. This
increased the intensity of environmental resistance to
plant growth in that site relative to the catchment pond.
The size of the maximum standing crop was not
related to the ambient soluble-P or nitrate-N concentra-
tions. However, the phosphorus tissue accrual of E. Egggg-

sum and E. canadensis among the habitats appeared to

 

reflect the soluble-P concentrations. In all sites the
tissue concentration of phosphorus and nitrogen in the

submerged hydrophytes indicated the environmental level

Dennis P. Tierney

of both elements was not limiting to plant growth. Seasonal
mean phosphorus tissue levels of the plants collected from
the wastewater sites were about 1.0% of dry weight. Values
for aquatic macr0phytes grown in natural lakes and streams
are 2 to 10-fold lower than those reported here. The

tissue nitrogen content noted here was similar to reported
literature values of 3 to 4% of dry weight.

Interspecific genetic differences in phosphorus
accrual were absent while the existence of such differences
were suggested for nitrogen accrual. Populations of each
species growing in more than one habitat exhibited signi-
ficant differences in phosphorus content, but not in
nitrogen accrual. Seasonal patterns of tissue-P in the
plants was fairly uniform while no trend was observed for
tissue-N. Generally, the rate of phosphorus uptake was
approximately equal to dry matter synthesis.

Mean tissue content of each trace element in E.

canadensis and E. demersum was determined over the periods

 

of growth up to and including maximum standing crop.

Quantities of trace elements were greater in E. canadensis

 

and E. demersum occurring in the Fowlerville wastewater
pond compared to the catchment pond. However, amounts of
some trace elements (Co, Cd, Pb, Fe) were higher in E.
demersum collected in the latter site than in the Belding
population. Pb concentrations were highest in the catch-

ment pond's E. demersum population than in either of the

Dennis P. Tierney

wastewater sites. The latter observation is attributed
to the Pb inputs from vehicle—industrial combustion asso-
ciated with an urban-industrial environment. The trace
element quantities ranked from least to most abundant
were similar regardless of the species or study site

(Cd < Co < Ni < Pb < Cu < Zn < Fe < Mn). A similar rank-
ing has usually been observed in other aquatic plants and
terrestrial plants.

Interspecific differences in trace element accumu-
lation was demonstrated between species coexisting within
a site. Differences in trace metal content in populations
of a particular species growing in more than one study
site was attributed to environmental variation in the
habitats. Seasonal mineral accumulation capabilities of
the plants was a dynamic process. The uptake and release
of elements varies as a plant ages. For example, the
pattern of accrual and release to the environment during
autumnal decomposition varied considerably from the one
observed during vigorous growth of the species earlier in
the season. The relationship between rate of net dry
matter production and net trace element uptake was complex.
In some cases, uptake of the element was approximately
proportional to primary production. The elements most
often accumulated in proportion to dry matter synthesis

were copper, nickel, lead and cadmium.

Dennis P. Teirney

E. canadensis and E. demersum at the wastewater and

 

the catchment pond had trace element levels several-fold
higher than in land plants. For example, cobalt was 15-30
times higher while zinc was 2-4 times greater. Other ele-
ments were intermediate to these values. Compared to

other studies of E. canadensis as well as other aquatic

 

plant species, the levels observed here were in the same
range.

Aquatic vascular plants remove large amounts of
phosphorus, nitrogen and trace mineral elements from a
pond or shallow lake basin. For instance, harvesting of

E. canadensis at maximum standing cr0p from the catchment

 

pond removed 3 mg of Co and 1.3 gm of Fe per kilogram of
plant (DW) biomass per hectare. The quantity removed by
harvesting depends on the size of the standing crop and
the tissue level of the elements. The former factor is
usually the predominate one. Planting and harvesting of
managed crops of aquatic vascular plants in wastewater
effluents would remove inorganic elements prior to dis-
charge into natural waterways. However, extensive land
area would be required to significantly remove the annual
inorganic discharge of even a small rural community.

Use of the harvested plant material as a feedstuff
and as a humus-organic fertilizer has been studied. While
a favorable Ca:P ratio occurred in tissue of the wastewater

grown plants, the high accumulations of trace elements

Dennis P. Tierney

appears to render the former use tenuous. Levels of copper,
cadmium and manganese were above toxic levels noted for
common herbage fed livestock. Addition of harvested

aquatic plants to soil appears to have more feasibility,
especially on sandy soils or in other regions where trace
element content is deficient or depleted. Lead levels

were also high and require attention due to its histori-

cal toxic effects on animal and human life.

SOME ASPECTS OF THE ECOLOGY OF NATURALLY OCCURRING
POPULATIONS OF SUBMERGED VASCULAR HYDROPHYTES IN
MUNICIPAL WASTEWATER LAGOONS I. PRIMARY
PRODUCTION AND PHOSPHORUS--NITROGEN
ACCUMULATION II. TRACE ELEMENT
ACCUMULATION III. POTENTIAL USE
AS A FEEDSTUFF AND A SOIL
CONDITIONER

By

L.

r
M

Dennis P? Tierney

A THESIS

Submitted to
Michigan State University
in partial fulfillment of the requirements
for the degree of

DOCTOR OF PHILOSOPHY

Department of Fisheries and Wildlife

1972

COpyright
Dennis P. Tierney
1972

TABLE OF CONTENTS

PART I

PRIMARY PRODUCTION AND PHOSPHORUS-
NITROGEN ACCUMULATION

INTRODUCTION . .
MATERIALS AND METHODS
RESULTS AND DISCUSSION .

Hydrophyte Production and Environmental
Resistance

Hydrophyte Production and Ambient
Nutrient Content . . . .

Hydrophyte Mineral Accrual
Hydrophyte Harvestability . . . .
CONCLUSIONS . . . . . .
REFERENCES CITED . .

PART II
TRACE ELEMENT ACCUMULATION

INTRODUCTION . . .
MATERIALS AND METHODS
RESULTS AND DISCUSSION . . . . . . . . . .

Interspecific and Site Variation in
Mineral Accrual . . . . . . .

Temporal Dynamics of Mineral Uptake

Comparative Mineral Accumulation

ii

Page

20
25
39
46
49

55
57
58

58
64
73

Page
CONCLUSIONS . . . . . . . . . . . . . . . . . . . . . 77
REFERENCES CITED . . . . . . . . . . . . . . . . . . 80

PART III

POTENTIAL USE AS A FEEDSTUFF AND A
SOIL CONDITIONER

INTRODUCTION . . . . . . . . . . . . . . . . . . . . 85
MATERIALS AND METHODS . . . . . . . . . . . . . . . . 87
RESULTS AND DISCUSSION . . . . . . . . . . . . . . . 88
Feasibility of Hydrophytes as a Feedstuff . . . . 88
Feasibility of Hydrophytes as a Soil Conditioner . 93
Other Considerations . . . . . . . . . . . . . . . 99
CONCLUSIONS . . . . . . . . . . . . . . . . . . . . . 100
REFERENCES CITED . . . . . . . . . . . . . . . . . . 101

iii

LIST OF TABLES

Table

PART I

Mean seasonal chemical composition of water
from study areas expressed as mg/l (ppm) where
appropriate . . . . . . . . . . . . . . . . .

Seasonal mean percentage of phosphorus and
nitrogen (DW) for Elodea canadensis and
Ceratophyllum demersum at three study sites
(1’2 SE) . i . . . . .. . . . . . . . . .

 

 

The dry weight ratio of calcium :phosphorus
in Elodea canadensis and Ceratophyllum
demersum grfiwing in the wastewater

and catchment ponds . . . . . . . . . .

 

 

Maximum net accrual of phosphorus and nitro-
gen (DW) potentially harvestable under a
one-crop format . . . . . . . . . . .

PART II

Quantity of trace elements in E. canadensis
and C. demersum (DW) based on mean tissue
contEnt up to and including period of maximum
standing crop (ug/gm t SE). Number of
analyses in parenthesis . . . . . . . .

 

Analysis of E. canadensis and C. demersum
interspecifiE trace eIément achmuIatlon
within a site and differential accumulation
of each species in different sites (Mann-
Whitney U Test) . . . . . . . . . . .'.

 

Percentage composition of ash and ppmvppt of
trace elements and amounts of these consti-
tuents per square meter in C. demersum grown
in Belding wastewater pond (Mean 1 SE)

iv

Page

14

22

38

42

60

61

65

Table

Percentage composition of ash and ppm-ppt of
trace elements and amounts of these constituv
ents per square meter in Ceratophyllum demersum

 

growing in Fowlerville wastewater pond
(Mean 1 SE) . . . . . . . . . . . . . . . .

Percentage composition of ash and ppm—ppt of
trace elements and amounts of these consiti-
tuents per square meter in Elodea canadensis
growing in Fowlerville wastewater pond

(Mean 1 SE) . . . . . . . . . . . . . . . . . .

 

 

Percentage composition of ash and ppm-ppt of
trace elements and amounts of these consti-

tuents per square meter in Elodea canadensis
grown in airport catchment pond_(Mean t SE) .

 

Percentage composition of ash and ppm-ppt of
trace elements and amounts of these consti-
tuents per square meter in C. demersum grown
in airport catchment pond (Mean 3 SE5 . . .

PART III

Average concentration of trace elements in C.
demersum and E. canadensis from wastewater _
ponds and a c§tchment pond in Michigan

(mg/kg plant dry weight) . . . . . . . . .

 

Approximate concentration of trace elements
in diet of livestock and man required for
normal growth and toxic disorders . . . . . .

Quantity of trace elements removed by a

one‘harvest format of submerged macrophytes
observed growing in wastewater ponds and a
catchment pond in Michigan . . . . . . . .

Milligrams of elements removed per kilogram
dry weight of submerged vascular plants
harvestable per hectare from wastewater ponds
and a catchment pond in Michigan . . . . . . .

Page

66

67

68

69

89

91

94

96

LIST OF FIGURES

Figure

PART I

Standing crops of Ceratophyllum demersum at
Belding wastewater site. Vertical lines
represent 1 2 SE. The mean net primary
productivity calculated from mid-July up to
maximum standing crop is indicated . . .

 

Standing crops of Elodea canadensis (solid

line) and Ceratophyllum demersum (dashed line)
at airportficatEhment site. ‘Vertical lines
represent 1 2 SE. The mean net primary pro-
ductivity calculated up to maximum standing crop
is indicated . . . . . . . . . . . . . . . . . .

 

 

Standing crops of Elodea canadensis (solid
line) and Ceratophyllum demersum—(dashed line)
at Fowlerville wastewater site. Vertical
lines represent : 2 SE. The mean net primary
productivity calculated up to maximum standing
crop is indicated . . . . . . . . . . . . .

 

 

Rates of growth of E. canadensis in the waste-
water and catchment—ponds. Doubling time (DT)
indicated for maximum and minimum slopes of
growing species . . . . . . . . .

 

Regression of tissue«P on ambient concentration
of solublevP for C. demersum collected from
airport catchmentTpond, BeIding and Fowlerville
wastewater sites. A regression of y = 5.196 +
2.31 x was obtained with a correlation coeffi-
cient of 0.86 significant at a 0.001 level of
probability . . . . . . . . . . . . . . .

Seasonal tissue content of Elodea canadensis

as percent phosphorus in Fowlerville wastewater
pond (o) and in the airport catchment pond
((1). Vertical lines represent 3 2 SE . . .

 

vi

Page

10

13

26

32

Figure Page

7. Seasonal tissue content of Ceratophyllum
demersum as percent phosphorus in Fowlerville
I05, Belding (o) wastewater ponds and airport
catchment pond (:1). Vertical lines
represent t 2 SE . . . . . . . . . . . . . . . . 33

 

8. Seasonal tissue content of Elodea canadensis
as percent nitrogen in Fowlerville wastewater
pond (o) and in the airport catchment pond (D) . 35

 

9. Seasonal tissue content of Ceratophyllum
demersum as percent nitrogen in Fowlerville
IOI, Belding (o) wastewater ponds and air-
port catchment pond (El) . . . . . . . . . . . . 36

 

vii

PART I

PRIMARY PRODUCTION AND PHOSPHORUS--
NITROGEN ACCUMULATION

INTRODUCTION

The man«made increase of inorganic nutrients to
lakes and streams has often set the conditions for tem—
poral and/or spatial imbalances in the production-
respiration steadyestate cycle. Nuisance growths of
algae and higher aquatic plants often reflect this instav
bility in the form of excessive organic production and
subsequent oxygen demand upon decomposition. The bio-
logic problems tied to inorganic nutrient release,
though similar, differ from organic waste disposal where
the oxygen demand to and assimilatory capacity of the
receiving water mass are the major parameters of inter-
est. These types of measurements tell little about the
effect of the effluent's inorganic load to the receiving
water (Rohlich, 1969). Sawyer (1944) noted this differ-
ence and the need to further treat sewage effluents to
remove the fertilizing elements. Odum (1971), in a
broader scope, has indicated the need to establish com-
partmental land—use procedures, whereby portions of a
watershed are designated as areas for development of
renewable fund and flow resource reclamation facilities.
Ideally, the concept would encompass the application of

ecologic principles and modern engineering technology

to achieve realistic water‘mineral recycling programs.
The recycling of fund resources (inorganic elements) as
well as flow resources (water) for application to bio-
logical resources (crops and soil) exemplifies Barry

Commoner's Second Law of Ecology. "Everything must go

 

somewhere” and the corollary that "we must learn how to
restore to nature the wealth that we borrow from it"
(Commoner, 1971).

Some wastewater recycling projects have been
demonstrated in recent years (Pennypacker g£_gl., 1967,
Merrell g£_gl., 1967). Usually conventionally treated
wastewater was sprayed or distributed to adjacent land
areas rather than directly discharged into a natural
stream or lake. Reduction of the nutrient-laden waters
occurred by filtration and adsorption processes within
the soil as well as biological uptake by the indigenous
vegetation. Aquifers, streams and lakes within the
watershed were recharged and the renovated water was
made available for further use.

A wastewater reclamation experimental facility
is planned for Michigan State University, East Lansing,
Michigan. As envisioned, conventionally treated waste-
water will flow through a series of shallow man-made
lakes prior to being discharged onto forest and agriculv
tural crops. In contrast to the use of man-made lakes

in the Santee project (Merrell et al., 1967) as a purely

recreational resource, the lakes and biota therein will
hopefully be important components in reducing the
nutrient-load of the recycled water, as well as provide
recreational uses. Aquatic vascular macrophytes are
depicted as biological management tools in reducing the
inorganic mineral concentration of the wastewater.
Managed harvests of this vegetation would be prepared
and used as a livestock fodder. Although several bio—
logical investigations of aquatic plants are available
on the growth and tissue composition of mineral nutrients
(Westlake, 1963; Boyd, 1967, 1969; Harper and Daniel,
1934; Riemer and Toth, 1969; Forsberg, 1960), few are
available on hydrophyte growth and mineral accural in
wastewater derived lakes or lagoons. Studies to date on
the phosphorus and nitrogen accumulation in aquatic vege-
tation have been conducted in relatively oligotrophic

or mildly eutrophic nutrient regimes where soluble-P
usually varied from 0.01 to 0.35 mg/l (Boyd and Hess,
1970; Boyd, 1970; Boyd, 1969; Forsberg, 1960). This
study was carried out in wastewater ponds where the
soluble'P generally ranged between 2.20 to 2.85 mg/l.
These environments were, then, extremely enriched in
regard to phosphorus. It was initially assumed that the
chemical milieu of the wastewater represented an enrich-

ment of other inorganic elements as well. To insure a

range of eutrophy, a non-sewage catchment pond was included
as a comparative baseline or "control" environment.

This paper considers the effect of a wastewater
pond's chemical regime on the growth, PeN accural, inter-
specific and habitat variation in P-N uptake and temporal
fluctuations in naturally occurring populations of sub-
merged hydrophytes. The use of the harvested hydrophytes
as a management tool for removal of phosphorus and nitro-

gen is discussed.

MATERIALS AND METHODS

Three study sites were utilized. One was a
catchment pond located on the property of the municipal
airport serving Lansing, Michigan. It lacks an inlet
and outlet, receiving water through precipitation, ground-
water seepage and surface runoff. Individual ponds in
established sewage—lagoon treatment facilities provided
the other two sites. These facilities consisted of
sequentially ordered five and three pond series serving
Belding (5,000 people) and Fowlerville (2,000 people),
Michigan, respectively. Neither, at the time of the
study, received industrial waste. It was primarily of
domestic origin.

Naturally occurring populations of submerged
hydrophytes were collected from the third pond at each

of these facilities and at the catchment site. Plant

species sampled were Ceratophyluum demersum and Elodea

 

canadensis. The former was present at all sites while

 

the latter was absent from the Belding location. Collec-
tions were obtained on a weekly to biweekly basis from
late May to mid«November during 1970. The sampling
method consisted of using the entire pond or a known
areal section as the "universe." Sampling points were
generated within the "universe" from a random numbers
table and individual samples obtained at the intersec-
tion of the coordinates.

Sample numbers ranged from three to ten. A float-
ing square-meter grid was used to quantitatively estimate
the standing crop on an areal basis. Material was clip-
ped, collected by hand, rinsed in the ambient water,
placed in plastic bags and stored on ice for the trip to
the laboratory. In the laboratory, samples were rinsed
of debris in tap-water and allowed to air—dry for 15
minutes. Specimens were then placed in a forced-air dry-
ing oven for 48 hours at 80°C. Wet and dry weights were
recorded after each procedure. The plants were subse-
quently ground in a micro-Wiley mill using a 40 mesh
screen. Homogeneous subsamples were obtained and stored
under dessication in glass bottles.

Chemical analyses were performed on the ground
subsamples of whole plants. The amount of phosphorus (as

P) in the tissue was determined spectrophotometrically by

a modification of the vannadomolybdate method of Rickey
and Avens (1955) subsequent to wet digestion. A mixture
of nitric and perchloric acid (3:1) to which 2.0 gm/l
sodium bromide had been added to remove arsenic, germanium
and silicon interference was used (Lueck and Boltz, 1956).
Nitrogen concentration (as N) was determined with a
Perkin-Elmer 240 Elemental Analyzer. Ash weight values
were obtained by dry digestion in a muffle furnace at
550°C for one hour. Statistical analysis of interspecific
and site variation in phosphorus and nitrogen accural was
performed according to Siegel (1956) and Sokol and Rohlf
(1969).

Water samples were obtained concomitantly with
the hydrophyte collections. Samples were gathered from
the water column at approximately one foot intervals using
a plexiglass tube and composited for each depth. All sam-
ples were stored in plastic bottles, preserved with HgCl
(Howe and Holly, 1969) and refrigerated prior to analysis.
The amount of phosphorus (as P) in the water was expressed
in mg/l of total and soluble phosphorus. Determination
consisted of acid hydrolysis, chloroform extraction
(Wadelin and Mellon, 1953) and spectrophotometric quanti-
fication of the molydophosphorus complex (Anon., 1969).
Nitrogen determinations were performed for nitrate-N,
nitrite-N, ammoniaeN and organic‘N and expressed as mg/l.

The latter three were analyzed according to procedures in

Standard Methods For the Examination of Wastewater and
Sewage (Anon., 1969). Nitrate-N was obtained by the
brucine sulfanilic acid method (Jenkins and Medsker,
1964). Hardness (Ca and Mg), total solids and pH were
also recorded (Anon., 1969). Temperature was obtained

by thermistor.

RESULTS AND DISCUSSION

Hydrophyte Production and Environmental
Resistance

 

Changes in the standing crops of the submerged
hydrophytes during the growing season are shown in Figures
1-3. The maximum standing crop of 410 gm/m2 occurred with

Elodea canadensis growing in the airport catchment pond.

 

It was about 4-fold larger than E. canadensis growing in

 

the Fowlerville wastewater pond. Where both species co«
existed, maximum standing crops of E. demersum were 3 to

4efold lower than E. canadensis. Relative to reported

 

values for emergent and submerged hydrophytes in the
literature, those observed here were several-fold lower
(McNabb E£_2l‘» 1971). Similarly, the net mean primary
productivity of the submerged plants up to the maximum
standing crop was generally less than the growth rates

of aquatic macrophytes observed elsewhere (McNabb g£_gl.,

1971). E. canadensis existing in the catchment pond had

 

the highest rate of 6.9 gms dry weight/mz/day. This is

.meMOAMGH ma mono mcapnmum EdEmeE on Aw >HSUI©HE Eoum pwumHDOHwo
>ua>wuofipoum mnmfiwum um: some use .mw N + ucmmmumou mocwa Hecauum>
.muflm Hmumzoummz mnflpamm um Edmumfimp Esaamnmoumumo mo mmouo weapcmum

 

HmQEo>oz umnouoo umnfimummm “mound wasp econ

.H mhsmflm

mm:

 

- . _ 4 E A _

. mme\~a\sm o.H
. gm

 

L

.0

10H

.om

tom

.om

om

uOOH

 

aqfitan £10 zw/s

.poumUApcw ma moao weapcepm Esafixes on

a: woumasoamo >uw>flpo3poum Sausage we: came 0:9 .mm N « Hammoaaon

mocfia Hmomuno> .oufim ucoenoumo phoneme um mocma ponmmpv sawhoEop
ESHHAHQOueaoU use mocflfi pfifiomv mwmcowmcmu mopon mo macho mcwpcmum .N chamfim

 

 

honEm>oz ponouoo Monsoumom .um:w=< Sands .mfish
_ A

 

 

 

 

 

 

 

m J 1 q . 1 1
oilloulllllol , To
”
I],
D ,
, 1 111/ law
Lwooa
.u mm.
4' .1?) W2
: G
1.oom
.M
9
II. T..
as
U;
1
IIIIIIIII .I .oom
Smw\NE\Em v.H EsmhoEop .u
xmp\ms\5m m.o mfimcopmcmo .m
.oov

 

 

10

.pouwoapcfi ma nope mcfipcmum EDwamE ow a:

woumfisuHmo Auw>wuu§poum kmeHHm we: came 0:9 .mm N u ucomoamoa mocaH
Hmowumm>I .ouam Hopmzopmmz oHHH>aoH30m um mocwa ponmmpv someoEop
Esfiaxdmoumhou can nocfla pwaomv mfimcopmcmo mopon mo mmouo wcwpamum

 

 

 

 

Monsoumom, umsmn< xHSh mama
_ d J J
D- g s L'o
. T
a ..o~
\\\\\e .\
1. : .13
1 no
/
W
z
1100 U
l
.A
.18 w.”
T:
00
u.
:53...
.I .uoNH
zwp\NE\Ew m.o EamHoEop .u
zmp\NE\Em n.H mwmcopmcwo .m..:¢wa

 

.m mesmfim

11

about 6-fold higher than the other values calculated for

(E. canadensis and E. demersum in this study. Where both

 

species were present, productivity rates of E. canadensis,

 

the dominant species,were 3 to 6-fold higher. Net pro-
ductivity rates were lower for populations of the hydro-
phytes grown in the wastewater ponds than in the catchment
pond. It would appear that the latter was the more opti-

mal environment for E. canadensis growth.

 

The question of which habitat presented the least
environmental resistance to the growth of the submerged
hydrophytes is not adequately resolved when only the net
mean productivity rates and size of the maximum standing
crops are used as the comparative measures. As indicated
by McNabb and Tierney (1972), the standard field method
of measuring vascular hydrophyte growth (i.e., unit
weight/unit area/unit time) is usually unsuitable for
ascertaining the degree of coupling of a hydrophyte's
genome to a particular environment. It does not consider
differences in the quantity of plant biomass initially
present. An alternative method involves comparing the
time required for doubling plant biomass (doubling time-
DT) as measured from the onset of growth to the inflec-
tion point of the seasonal growth curve. The inflection
point represents the approximate period in which some
resource (as nutrients, lights, temperature) becomes

limiting. If the maximum doubling time (unlimited rate

 

12

of growth) is known for a species, the relative suitability

 

of any particular habitat can be determined for that
species from several measurements of standing crop in the
period up to the inflection point. This period is termed
the accelerating phase of growth and when doubling time is
at a maximum in this period, the plant theoretically
grows in an unlimiting environment with respect to its
chemica1«physical requirements.

Figure 4 indicates the doubling time (DT) of E.

canadensis in the airport catchment pond and the Fowler“

 

ville wastewater site. The rates were calculated using
analogous portions of the growth curves up to the inflec-
tion point. It can be seen that the wastewater site

offered less resistance to Elodea canadensis growth as

 

exhibited in a mean DT 4«fold faster than in the catch-
ment pond population. The wastewater pond, though con-
sidered limnologically extreme in nutrient levels (Table
1), represents the more favorable habitat for E. canaden-
glg. The genotype of this species is apparently more
fitted to the hypereutrophic conditions of the wastewater
pond. Genetic similarity of the populations is assumed.
Losses of biomass during the interval of measurement to
grazers or to decomposition were considered negligible
on the basis of field inspections.

Doubling times of 12 and 11 days were reported

by McNabb and Tierney (1972) for Elodea nuttallii and

 

13

.m0fioomm mcfizoaw mo momon
EDEficfis paw EDEfime how woumonCH ”Haw mmwu mcHHpsom

.mwcom

 

     

unmeaoumo was pouwzoummz esp :fi mflmcopmcmo .m mo auzoam mo mmumm .v oaswflm
mxmm :H mafia
om oe om om OH o
1 _ _ _ _ _
1.0

T

o

B

I

0

W

9

e

u

1.o.H M

A

M

e

T:

chdQ ma BO. am.

\|&‘\\) 1

. I.

pcom . u

Houmzopmmz ..o N 9

60? 1

Na 9D e m

m>aa 11

wcoa W

pcosnoumu

m>ma mN Ha

 

l4

.moHQEmm wH-mH mo owmue><m

 

 

 

SH.” No.” ao.w ma
m~.m ma.m Ha.m z-Hauoe
os.H HN.N mm.~ z-uaeamao
ma.H Nm.~ Nm.o z-uaeamao:H
mH.H mo.~ em.o z-aa:oee<
AH.o mH.o oo.o z-mpaapaz
mH.o afl.o 8H.o z-muaauaz
mm.~ o~.~ oa.o a-ouanamoea mansflom
on.m sm.~ m~.o a-ouaeamoea Hauoe
N¢.m¢o NH.ooo om.ao~ meuaom .a.e
N¢.HNm ou.oa~ on.HmH mmoceaam
-MMMMWm wafipaom whoanfi<

mfimzamc<

spam

 

 

«.0umflumonmme
muons flammv H\ma mm commonnxo mamas heapm
Eoum Hope: we cowufimOAEOU Hwofleono accommom new: .H manna

15

Ceratophyllum demersum, respectively. Vegetative growth

 

of both species occurred in wastewater ponds; the former
in the Fowlerville pond used in this study and the latter

in an Auckland, New Zealand pond. The DT of E. canadensis

 

measured in this study was 4-fold faster. Its adaptability
for vegetative growth in hypereutrophic environments seems
to be superior to the former species. However, the
chemical-physical conditions of wastewater ponds are not
always similar and this conclusion can only be considered
tentative.

No comparative doubling times were calculated for
E. demersum, since it was the subdominant species in two
sites (Figures 2 and 3) and was therefore considered to
be limited primarily by the biological interaction with

E. canadensis, rather than the chemical environment of

 

the respective ponds. However, the trace element accural
of the two species was not identical within a site
(Tierney, 1972a). The environmentally toxic concentra-
tion of an element(s) varies among terrestrial flora
(Bowen, 1966). There is no reason to doubt the existence
of aquatic species which are relatively tolerant of trace
metal concentrations found inhibiting to other hydro-
phyte species. The possibility of interspecific toxic
metabolic suppression of E. demersum cannot presently be

ruled out.

16

Evidence also points to a potential physical con-
trol, namely, ambient water temperature, on the photosyn-
thetic rate of E. demersum. Laboratory studies of Saitoh
g£_gl. (1970) indicate that 30°C is the optimum tempera-
ture for the highest apparent photosynthetic rate in E.
demersum. No readings reached this level during this

study. The obvious dominance of E. canadensis over E.

 

demersum as seen by the standing crop measurements may be
the result of temperature regime relatively more optimal
for the former species and it therefore would have a
higher rate of photosynthesis. The result of such a

condition would find the faster growing E. canadensis

 

eventually producing a shading effect on E. demersum
and limiting incident radiation available to it. The
biologic effect of shading combined with the suboptimal
water temperature could further reduce the rate of photo-
synthesis in E. demersum.

Even though the wastewater pond was the more

optimal environment for E. canadensis as determined by

 

the faster doubling time, the maximum standing crop
achieved by it was lower than that observed in the catch-
ment pond. Presumably, it would double 4-fold in weight
in the time it takes the catchment pond population to
double once and thereby eventually surpass it. However,
two factors are responsible for the lower maximum stand-

ing crop at Fowlerville; the variable intensity of

17

environmental resistance and the initial seed or vegeta-
tive shoot density. Doubling time is a measure of the
former, but not the latter. As can be seen in Figures 2
and 3, the size of the initial standing crop of E.

canadensis at the onset of growth was about 50 and 6

 

gm/m2 in the catchment and Fowlerville ponds, respectively.
This is an 8-fold difference in dry weight. This initial
difference puts limits on the eventual size of the stand-
ing crop.

Ideally, the study was organized to follow the

growth of E. canadensis in the ponds through similar

 

periods of the year. This was done in an effort to have
roughly similar light and temperature regimes at both
sites. In that event, the main environmental variable
between sites would be the chemical regimes of the ponds.
Plant density and occurrence of annual growth were approx-
imately similar at both sites based on observations from
the previous year. However, an unfortunate incident
occurred in the Fowlerville site in the fall which altered
these conditions.

Personnel of the Fowlerville sewage facility
mechanically uprooted the submerged hydrophytes. One
effect of this effort was to reduce the overwintering
plant biomass and thereby reduce the size of the initial
plant biomass in the spring. The other effect of macro-

phyte uprooting was to delay the onset of growth (Figure 3).

18

This shift obliterated any possibility of measuring the
growth of the two populations during the same time of
the year. Consequently, the effect of the chemical

regimes on the growth rate of E. canadensis is more

 

difficult to assess.

Figure 4 illustrates the reduction in growth rate
which occurred in late August and September to E. canaden-
iii in the wastewater pond. A doubling time of 19 days
elapsed from the inflection point of the growth curve up
to the maximum standing crop (Figure 3). The correspond-

ing duration of growth for E. canadensis in the catchment

 

pond was about 25 days. The wastewater population experi-
enced a 6vfold reduction in growth rate (3 to 19 days)
while the catchment pond population had a vaold reduction
(12 to 25 days). Apparently, the environmental resistance
of the wastewater site increased considerably more than
the catchment pond. This unequal variation in intensity
of environmental resistance combined with the lower vege-
tative shoot density accounts for the lower maximum

standing crop of E. canadensis in the wastewater site.

 

It is felt that the increase in environmental
resistance observed in the wastewater pond is related to
changes in two physical parameters, namely, ambient water
temperature and solar radiation, rather than any substan-
tial shift in the chemical melieu of the pond. The uproot-

ing of the plants shifted the growth phase of E. canadensis

 

19

into August and September where rate-limiting effects of
falling water temperature and subsiding solar radiation
predominately slowed its growth rate. Water temperature
declined from a summer high of 28°C to 18°C from mid-July
to the end of September in the Fowlerville wastewater
pond. It remained near 25°C from mid-June to mideAugust
in the catchment pond. These temperatures occurred
simultaneously with the onset of growth and continued
through the determination of maximum standing crop. It
is known that temperature effects the metabolism of
plants and the relationship is expressed in the form of
the Q10 approximation, where a 10°C degree rise or fall
in ambient temperature produces a corresponding Z-fold
change in the plant's metabolic rate (Galston, 1964).

Reduction in the metabolic rate of E. canadensis, based

 

on the comparative seasonal temperature reductions, would
appear to be significant in the wastewater situated
population.

The seasonal reduction in solar radiation was
similarly more significant throughout the growth of the

wastewater situated E. canadensis. The quantity of

 

direct solar radiation striking a water surface decreases
approximately 31% from mid-July to mid—September, and
only 12% from mid—June to mid-August at 45°N latitude
(Perl, 1935). The maximum quantity of total direct

radiation occurs in mid-June. Presumably, the autumnal

20

shift in direct solar radiation followed a similar pat-
tern in the study ponds, though the absolute quantity
of radiation delivered would vary due to local climatic
conditions and the 42° N latitude position of these
ponds.

The effect of differences in temperature and
light was a striking increase in environmental resistance

to the growth of E. canadensis in the wastewater site

 

after growth had begun as compared to a more gradual
shift observed in the catchment pond. The relatively
larger shift in intensity of environmental resistance

in the wastewater site, particularly in late August and
September, contributed to the striking decrease in doubl-
ing time seen in Figure 4. The size of the maximum
standing crop in the wastewater site was, therefore,

less than that observed in the catchment pond.

Hydrophyte Production and Water
Nutriént Concentration

 

 

The size of the standing crops was not correlated
with the concentration of soluble phosphorus in the water.
A comparison of Table l and Figures 1 through 3 indicate
this point clearly. The catchment pond had the largest
standing crops and the lowest soluble phosphorus concen-
tration. Boyd and Hess (1970), however, found a positive

correlation between dissolved phosphorus in the ambient

21

water and the size of Typha latifolia standing crops from

 

various habitats. The absence of a stimulatory effect of
high soluble phosphorus concentrations on submerged hydro-
phyte growth in this study may be explained with the use
of the luxury consumption and critical nutrient concentra-
tion concepts.

Gerloff and Krombholz (1966) established a tissue
phosphorus critical concentration of 0.13% for several
aquatic macrophytes in laboratory experiments. Below this
value the plant content of phosphorus is closely correlated
to plant yield, while phosphorus tissue content above this
value represents luxury uptake and has no stimulatory ef-
fect on plant yield. The lack of relationship between
standing crops (yield) in the catchment pond and the
wastewater ponds and their respective ambient soluble
phosphorus concentration is apparently due to the fact
that the phosphorus tissue content is approximately 4
to 8-fold higher than the critical concentration level
established by Gerloff and Krombholz (Table 2). Phos-

phorus tissue levels of E. canadensis and E. demersum

 

are, therefore, in the luxury consumption zone. The

phosphorus tissue concentration is no longer considered
limiting to growth, so differences in the ambient water
concentration would not be reflected in the size of the

plant yield.

22

.pcom unbecopmun
.pcom Houmzoumwzm

 

Nm.o H mm.m oo.o H Hm.o wH.o H mH.m oo.o H mm.o

NH.o H mm.v NH.o H mo.H 1-- 1--

n

w

HHOQHH<

meaefiom

om.o H Nv.v va.o H NN.H NN.o H ~w.m. NH.o H mo.H moHHH>HoH30m

 

 

 

 

 

 

 

 

z a z a
IIIIIIII. I. I ouHm
EdeoEow .u mHmcopmcmo .m
.mmmm+v moumm Smoum omega um
Eamaosop azaaxdmoumaoo paw mHmcopmcmo mowoam How many
comoHHHc paw mzuoammonm mo ommucoohom came Hm:0mwom .N oHan

23

The phosphorus tissue levels of Typha latifolia

 

in Boyd and Hess's (1970) study are much closer to the
critical phosphorus concentration and approximately 20%
of the samples are equal to or lower than the 0.13% value,
while the mean tissue phosphorus content was only 0.21%
dry weight. Given the variability of field conditions
and the controlled nature of laboratory studies, the cri--
tical phosphorus tissue concentration of 0.13% is to be
understood as an estimation and variability about this
value is to be expected. Therefore, the correlation
between soluble phosphorus and aquatic plant yield would
be more likely to occur with the nutrient concentrations
observed by Boyd and Hess, where it is feasible that the
critical phosphorus tissue concentration had not been
obtained.

Seasonal mean tissue nitrogen concentrations
(Table 2) of the submerged hydrophytes collected from all
sites were 2 to 4-fold higher than the nitrogen critical
tissue concentration of 1.3% also established by Gerloff

and Krombholz (1966). Again, E. canadensis and E. demer-

 

32m were apparently in the luxury consumption zone for
this element. The differences in water nitrogen (as
nitrate) concentrations among the ponds would seemingly
not be reflected in the size of the yields (standing
crops) observed in the ponds. Boyd and Hess (1970) found

no correlation between ambient water concentrations of

24

nitrogen (as nitrate) and the size of standing crops in

Typha latifolia collected from several habitats. Tissue

 

concentrations of nitrogen in approximately 70% of his
samples were larger than the critical concentration of
Gerloff and Krombholz.

Differences, then, in water concentrations of
either elements are apparently not reflected in the size

of the standing crops achieved by E. canadensis and E.

 

demersum. Both phosphorus and nitrogen water concentra-
tions appear to be unlimiting to growth in the wastewater
and catchment ponds. In terms of Gerloff and Krombholz's
critical concentration factors, all sites are nutrient
rich regarding these elements.

It should be cautioned that the relationship
between nutrient water concentration and plant growth is
complex. Obviously, environmental conditions are more
varied, dynamic and complex in field studies than with
the laboratory experiments of Gerloff and Krombholz from
which this analysis draws heavily. That other environ-
mental factors (as light and temperature) also influence
growth rates should be recognized and was noted in the

previous section.

25

Hydrophyte Mineral Accrual

 

The mean seasonal tissue accumulation of phos-

phorus by E. canadensis and E. demersum was vaold higher

 

in the wastewater populations than in the catchment pond
populations (Table 2). This difference is statistically
significant (Kruskal-Wallis anova, a level 0.001). That
this difference was a reflection of the environmental
variation in phosphorus concentration is seen in Figure
5. The relationship between E. demersum tissue concen-
tration and the external phosphorus water level is noted.
The mean tissue-P content is regressed against the mean
soluble phosphorus (as P) water concentration for the
three sites over the period of June 30 to August 20.
This corresponds to the period of growth from the onset
up to and including the achievement of maximum standing
crop. A significant correlation was obtained between
the external phosphorus level and the internal tissue-P
accumulations. Specifically, as the water concentration
of phosphorus increased from the catchment pond through
Belding and Fowlerville wastewater sites, parallel in-
creases were noted in the tissue content of E. demersum.

Though E. canadensis was absent from the Belding

 

pond, the accrual of phosphorus in this species seems to
also increase in response to increased environmental

concentrations (Table 2). For example, there is no

26

.suafianmnoaa mo Ho>oH Hoo.o a pm

. pcmonHcmHm om.o mo ucoHonmoou :oHHmHoHHoo m :sz poaHmp
-no mm: x Hm.m + omH.m n x we GOHmmonoH < .mouHm Houmzoummz mHHH>
-Hoazom paw mcwpaom .pcom u:oE:owmo whomhwm Eopw popooafiou EmmHmEow
.w How m-oHn:Hom mo coHumecoocoo pcoHnEm co msoSmmHu mo :onmonom

 

H\me a-ofinsfiom
o.a o.m o.~ o.H

q u a d u d a u

 

I I
N O
H H

r
V
H

 

 

.m opstm

201 x mdd » snloquoqd ensstl

27

interspecific phosphorus tissue accrual difference between

E. canadensis and E. demersum coexisting in either the

 

catchment pond or the Fowlerville site (Kolmogorov-Smirnov,
a level 0.01). Apparently this indicates there is a
similar response by the submerged plants to the environ-
mental levels of phosphorus encountered in this study.
Additionally, Adams g£_gl. (1971) found the tissue-P

concentration of E. canadensis increased significantly

 

from clean water conditions to nutrient-enriched water
encountered downstream of domestic and industrial dis-
charge pipes.

Nitrogen accrual by coexisting populations of

E. canadensis and E. demersum is statistically similar

 

within the catchment and wastewater sites (Kolmogorov-
Smirnov, a level 0.05). Though interspecific nitrogen
accumulation is not statistically evident, E. demersum
uniformly contains greater quantities of nitrogen
(Table 2).

While there existed distinct site differences
in the tissue-P level of the submerged plants, nitrogen
accumulation was not so clearly demarcated. ‘E. demersum

and E. canadensis grown in the Fowlerville site contained

 

larger amounts of N than populations collected from the
catchment pond (Table 2). However, this difference was
only significant at an a level of 0.10. Yet, tissue-N

levels of E. demersum were significantly higher in samples

28

collected from Belding than from the airport catchment
pond (Kruskal-Wallis, a level 0.001). Presumably, since
the nitrate-N and totalvN water concentrations were sta-
tistically similar in the three ponds (Kruskal-Wallis,
a level 0.20) and the soluble and total-P water concen-
trations were statistically higher in the wastewater
sites (Kruskal-Wallis, a level 0.01), the nitrogen gradi-
ent among the ponds was smaller than the phosphorus
gradient (Table l). The result is that the wastewater
ponds are distinctly different in P concentration from
the catchment pond while less distinction exists in nitrate-
N and total-N water concentration. For these reasons, the
seasonal mean nitrogen content in E. demersum did not
exhibit the relationship seen in Figure 5 for tissue-P
accumulation.

The wastewater ponds' nitrite—N and ammonia-N
levels were significantly greater than values observed
in the catchment pond (Table l). AmmoniaeN, as well as
nitrate-N, is absorbed by plants (Price, 1970). Though
the total-N and nitrate-N values were similar for all
sites, the relatively greater availability of the absorb—
able nitrogen species in the wastewater sites may account
for the slightly higher tissue-N levels observed therein
(Table 2).

Though interspecific phosphorus accumulation

within a site is not evident between E. canadensis and

 

29

E. demersum, interspecific variation in phosphorus
accrual has been observed by Boyd (1970). Several species
of emergent, floating leafed plants and submerged plants
exhibited different tissue-P quantities while coexisting
in the same pond. Gerloff and Krombholz (1966) also
found phosphorus as well as nitrogen variation in subs
merged macrophytes collected from Lake Mendota, Wisconsin
just as Schuette and Alder (1927, 1929) did nearly forty
years earlier. Stake (1967, 1968) demonstrated such
interspecific mineral accrual as well.

Several instances of tissue phosphorus and nitro-
gen content varying among populations of an aquatic
macrophyte with a cosmopolitan distribution are known
(Boyd, 1969, 1970b; Adams E£_El°» 1971; Gerloff and
Krombholz, 1966; Caines, 1965). Such differences are
usually attributed to the relative fertility of the
various habitats. Caines' (1965) investigation experiv
mentally demonstrated a parallel increase in tissuepP
of two submerged species after fertilization of a Scotish
loch. However, it should be noted that other aquatic
plants present actually exhibited a reduction in tissue-P
after fertilization. Plant response, then, to increasing
environmental nutrient levels is not clear-cut and prob-
ably differs with both species and individual elements as

Boyd and Hess (1970) noted.

30

Boyd (1967), in a review of aquatic plant mineral
composition, indicated that submerged plants generally
contained 3 to 4% nitrogen by dry weight. As seen in
Table 2, the nitrogen content here is fairly compatible
with that estimate. Phosphorus levels for aquatic angio-
sperms ranged from 0.1 to 0.6% by dry weight (Boyd, 1967).
Other investigators indicated phosphorus tissue levels
are generally within this range (Stake, 1968; Gerloff and
Krombholz, 1966; Caines, 1965; Boyd, 1970d). Only Adams
g£_gl. (1971) observed tissue levels of ~1.0% phosphorus
which were approximately similar to values noted in Table

2. The latter study also examined E. canadensis from

 

extremely eutorphic habitats and apparently confirms the
tissue—P accrual noted in the wastewateregrown plants.
Overall, the levels reported here were 2 to 10efold
greater than those reported for aquatic vegetation col-
lected from less eutrophic lakes and streams.

Temporal variation in tissue-P content of the
submerged hydrophytes is indicated in Figures 6 and 7.
Phosphorus tissue levels in the aquatic vegetation col-
lected from the catchment pond was fairly constant through-
out the summer and fall with rather uniform standard
errors about the means. However, variation about the
means was more pronounced in the wastewater-grown plants
and the tissue«P level varied widely over the seasons in

E. demersum while levels were somewhat more uniform in

31

E. canadensis observed in the Fowlerville wastewater site.

 

Apparently, the higher environmental phosphorus concentra-
tion promotes a greater variability in individual plant
accrual of phosphorus. Adams et a1. (1971) also noted

increased variability in tissue-P content of E. canadensis

 

collected from a habitat of high ambient phosphorus con-
centration compared to samples obtained from an area of
low ambient phosphorus levels. Generally, tissue-P levels
were also higher during the summer for both species
sampled from the wastewater sites than the catchment
habitat, but values approached levels observed in vegeta-
tion from the latter site by late fall.

Literature values indicate that the phosphorus
and nitrogen content of aquatic emergent and submerged
plants declined as the plants aged (Boyd, 1970a; Stake,
1967, 1968; Caines, 1965) or varied indiscriminately
(Gerloff and Krumbholz, 1966). Presumably, the percentage
decline in macronutrients with growth observed by the for-
mer authors is the result of a mineral uptake rate less
than that for biomass synthesis. The fairly constant
seasonal phosphorus content of E. demersum in the catch-

ment pond and E. canadensis in the sites where it occurred

 

indicates the rate of phosphorus accrual is fairly close
to the rate of biomass synthesis. An inspection of
Figures 2-3 with Figures 6-7 indicate this relationship
during the period of growth up to and including the

achievement of maximum standing crop.

32

.mm N H Hammoamoh mmcHH HmoHpHo> .mna econ
peoEAOHmo whomaHm may :H mam new NMom Houmzoummz oHHH>Honom :H
monogamonm pqmoaom mm mHmcowmcmo mopoam mo pcopaoo oommHH Hmcommom

 

I Honfio>oz Honopoo Hensoummm umsms< hash meow
. . _ _ _ _ o

 

1
m
(D

l
O
H

 

 

I
U)
H

.o oHDMHm

itheM A13 4 snioquOQd lueoled

.mm N H ucommpmoh mocHH HmoHpHo> .nnuv wcom pcoenoumo HHoQHHm
paw mucon Houekoummz now mcHwHom .nev oHHH>HoH30m :H mononmmoca

 

Hemopom mm ESmHoEop Enafixcmopwaou mo pcoocoo osmmHH Hmcommom .5 oasmHm

HonEo>oz Honouoo Hensoumom Hmsm5< hand wash km:

 

q d _ A 4 . a

33

 

 

A

 

 

m.o

m.H

ithsM Ala - snioquoqd iuaoied

34

Seasonal patterns of nitrogen accrual are noted
in Figures 8 and 9. No clear trends can be noted.
Obviously, the general decline noted by the above-
Imentioned authors is absent. A suggestive decline occurs
with the onset of growth as a comparison of Figures 1 to
3 and Figures 8-9 indicates, but tissue values increase
at or prior to achievement of maximum standing crop.

No mention of direct inorganic phosphorus toxiv
city is found in the literature (Bowen, 1966). However,
high levels of phosphorus or calcium in forage can
indirectly hinder normal growth and development in
domestic ruminants (Underwood, 1966). Adequate phosphorus
and calcium nutrition depends on a low calcium to phos-
phorus ratio in the feed or forage. Dietary ratios
between 1:1 and 7:1 gave the best results in growing
Hereford calves while values between 1:1 to 3:1 are
favorable for growing chicks and pigs (Underwood, 1966).
The presence of ratios outside of these limits indicates
an excess of one element or the other. This excess
interfers with absorption of the other element and with
several mineral nutrients, such as magneisum, zinc and
manganese. Deficiency signs may, therefore, be induced
in the livestock for those elements. Indirectly, then,
high tissue-P levels may render forage vegetation unsuit-

able in the presence of normal calcium levels.

‘1’...“

 

35

An: econ
uncanoumu HHoQHHm one :H pee any pawn Hopezoummz oHHH>HoH30m GH
:omoauwc Hcoohmm we mHmcopmzmo .m we acoucoo oommHu Hmcommmm

 

HonEo>oz Honouoo Hensoumom Hm3w3< Sana mash
TI . _ _ . .

 

 

.w oHDMHm

JV
1 v.~.d
9
l
3
9
u
1+
o m N
I.
1
l
0
Q0
9
U
1
. G
-o v 1
1A
M
9
I.
00
Us
1

_L
o
m

 

ADV Econ unmenoumo toe:
use mucom Houmzoumez hog mammaomI.moV oHHH>HoH30m :H ammoHHH:
unmouom mm ESmHoEow Esfiaxamoumhou mo Hcoucou enmmHH Hmcommom .m oasmHm

 

36

HonEo>oz Honouoo Hensoumom Hmsws< Sash 0:35 km:
_ _ _ q _ .1 1%
J

I v.N
.d
9
I
3
9
U
.. o.m 1
N"
T...
I 1
1
O
u an
9
I I u
. . . 1 o.v”w
O 9 IA
_M
9
o o _.L.
o o 00
U:
0 o 1

o o u
1 o.m

 

37

The ratios calculated for E. canadensis and E.

 

demersum are indicated in Table 3. The ratio was obtained
from the seasonal mean tissue concentrations of phosphorus

and calcium. E. canadensis sampled from the catchment

 

pond is limited as a forage to ruminants only. As far as
the nutritional requirements of livestock is concerned,
the most favorable ratios occurred in the wastewater
populations. Apparently, the higher tissue-P levels in
these populations established a lower Ca:P ratio. From
this standpoint, the submerged hydrophytes appear suit-
able as an animal fodder.

As noted by Tierney (1972b), trace element
accrual may limit such a feasibility. Also, the potential
for nitrate poisoning in livestock from submerged hydro-
phytes is unknown. Normally functioning terrestrial
plants usually contain relatively small amounts of
nitrate, but under certain environmental conditions
fairly high concentrations of nitrate may accumulate
(Tucker E£_El-1 1961). Since only the total nitrogen

content of E. canadensis and E. demersum was ascertained,

 

no data is available on the tissue nitrate concentration.
Wick and Sandstrom (1939) found essentially no nitrate-N

in the tissues of E. canadensis collected from a small

 

stream. The difference between such a habitat and the
chemical regime of the wastewater ponds should be sub-

stantial. Examination for nitrateeN and other nitrogen

38

 

 

 

 

Hum: Hum Hum ESmHoEow .m
- Hum: Hum: mHmcopmcmo «m
mewpfiom oHHH>Hoazom HHoQHH<
-moHoonm
spam

 

 

.mmcom pcoegopmo use Houmzopmwz on» :MImcmkon

 

 

EDmHoEop EDHngmwumHou paw mHmcopmcmo moonm
:H mahonamonmnesHono mo oHumH uanoz zap one .m oHnme

39

compounds as well as phosphorus compounds needs to be per-
formed on submerged hydrophytes grown in wastewater. The
qualitative composition is as important as the purely

quantitative determination.

Hydrophyte Harvestabiligy

 

The use of aquatic vascular plants as a means of
mineral nutrient removal from hypereutrophic waters has
been suggested by Boyd (1970) and others. Some basic
ecological information has been gathered on primary pro-
duction, growth rates and mineral composition of vascular
hydrophytes. This has, in turn, stimulated discussion of
their role as nutrient sinks in aquatic ecosystems as well
as the feasibility of harvesting these sinks. Such rea-
soning led, ultimately, to the question of how to dispose
of the harvested aquatic weeds. Several investigators
have directed their activities to the use of hydrophytes
as novel sources of protein for man and as fodder for
domestic livestock. To this end, numerous proximate
analysis studies have occurred assessing the nutritive
value of various species (Boyd, 1968a, 1968b, 1969;
Little, 1968; Lindstrom and Sandstrom, 1939; Nelson and
Palmer, 1939; Gortner, 1934). However, few feeding
studies exist demonstrating the actual dietary value
of vascular hydrophytes to domestic livestock or to man.

Furthermore, it has not been demonstrated that removal

40

of vascular hydrophytes stabilizes or reduces the eutro-
phic state of the treated lake or stream. Bartsch (1972)
feels harvesting aquatic macrophytes is not effective as
a method of nutrient removal for lakes in general, rather
its effect is cosmetic. However, such mechanical crop-
ping is not entirely undesirable and in certain instances
is economically and politically favored (Thompson, 1972).
Yet, more direct methods such as diversion of nutrient-
laden effluent (Edmondson, 1972) and. the dilution of
nutrient-rich waters (Oglesby, 1969) entering a lake or
stream have controlled the rate of eutrophication in
certain instances and appear more feasible as direct
eutrophication control measures.

Derr (1972), Boyd (1971), and others have stated
that a nutrient removal program designed to decrease
aquatic productivity by removal of dissolved nutrients
would be most effective if applied to effluents prior to
discharge into a lake or stream, and if a method(s) was
sought to remove all or most nutrients. Generally,
eutrophication control procedures center on the use of
chemical processes as the vehicle for nutrient removal
(Rohlich, 1969; Rohlich and Uttormark, 1972; Derr, 1972).
As seen earlier in this paper and in Tierney (1972a) as
well as Boyd (1969, 1970a, 1970b), aquatic vascular
plants accumulate several essential and nonessential

inorganic elements and thereby appear to meet the

41

abovementioned criteria. If intensely managed communities
of selected aquatic vascular plants were grown in waste-
water stabilization ponds, nutrient removal by harvesting
may be more than cosmetic and aid in reducing the dissolved
nutrients concentration in the wastewater discharge. Yet,
to date, information on the quantities of nutrients
actually removable has not been demonstrated lfl.§i£21

nor are cost estimates available for incorporating aquatic
plant harvesting procedures into established wastewater
stabilization systems.

Table 4 indicates the quantity of phosphorus and
nitrogen harvestable from the wastewater and catchment
ponds of this study. For example, under the climatic
conditions of this study, one acre with a one-cropping
format would remove ~l6 pounds of P at the Fowlerville
site; the discharge of 5 persons per annum as calculated
on the basis of 3.2 lbs (DW) of P per person per year
(Van Vuran, 1948). Nitrogen removal consists of 58
lbs/acre, the equivalent discharge of 5 persons as well,
calculated on a waste of 11.4 lbs of N per person per
annum (Van Vuran, 1948). The original phosphorus (as P)
level was adjusted upward to account for increased con-
sumer use of phosphorus detergents.

Based on Rohlich and Uttormark (1972), 5-50% of
N and P is removed through primary treatment and conven-

tional activated sludge systems. Presumably, the removal

42

.oanmoHHmmm when: moHoomm Anon mo Hmpoem

 

 

 

HH.HmH wm.w~ HHoQHH<
Hm.sm Ha.mfi mHHH>aonoa
mm.wm Aw.a meaefiom

z a
scam

ouow\maa mawuoe

 

 

.meHom mono-6:0
m Hope: oHanmo>Hmn xflamwucouom mmwmmn any
domoHHH: use msaonmmona mo Hmsaoom Ho: ESEmeZ .v 2an

43

efficiency in conventional wastewater stabilization
treatment operations would be within this range. Assum-
ing a mean seasonal efficiency of about 25%, the residual
quantity of P and N not removed and therefore available
to the macrophytes would be equivalent to approximately
2.4 lbs P per person per year and 8.5 lbs of N per
person per year. The harvested plants from Fowlerville
now represent the discharge of 7 persons per annum for
P and N.

The stabilization pond at Fowlerville was about
5 acres, large enough to only accumulate and remove the
P and N discharge of ~35 persons per annum. The city
of Fowlerville has about 2,000 inhabitants. Approxib
mately 285 acres would be required to remove the P and
N load by harvesting the indigenous species of unmanaged
submerged hydrophytes. However, the land area required
could be reduced if intensive management of the hydro-
phytes increased the primary production and the number
of harvests per year. Data by McNabb g£_gl.(1972) and
McNabb and Tierney (1972) indicate higher production is
achievable than what was observed here and several cut-
tings a year is not unrealistic for hydrophytes found
favorably "fitted" to the chemical regime of the hyper-
eutrophic wastewater systems. Assuming three cuttings
at the maximum standing crop observed in Fowlerville

with the naturally occurring unmanaged plants, the

44

acreage requirement is reduced to about 95 acres. Doubl-
ing the size of the standing crop at the time of harvest
would tend to lower the acreage needed to ~48 with three
cuttings. One could, then, increase the retrival of P
and N by intensely managing hydrophyte growth, increas-
ing the number of harvests and obtaining the tissue levels
of P and N reported here from the wastewater ponds. How—
ever, the cost of daily operation and initial cost of
land may prove to be prohibitive.

An acre of land in the vicinity of small mid«
Michigan towns has an appraised value ranging from
175 to 2,000 dollars depending on a number of socio-
economic variables (Larson, 1972). The estimated cost
for 48 acres would range between $8,400 and $96,000 for
a community the size of Fowlerville. This represents
only the initial cost of land acquisition and does not
include the costs of construction, maintenance, harvest-
ing and disposal of the hydrophytes. Nor are estimates
of the revenue generating capacity of the harvested
plants as animal forage available. Comparative nutrient
removal cost estimates are available by Rohlich (1969),
Rohlich and Uttormark (1972), and Derr (1972) for conven-
tional treatment plants. Land costs should be roughly
similar per acre; however, chemical nutrient removal
processes require less acreage and are usually incor-

perated into the existing facility. Total land costs

45

should be lower. Presently, the use of aquatic plants
for nutrient removal appears to be faced with limitations
due to the land area required, variability in size of
standing crops and limited growing season in temperate
climates.

In addition to the question of land requirements
and associated costs, biologic problems of disposal upon
harvesting require further attention. For instance, the
possibility exists of heavy metal accrual in the hydro-
phytes which would pose problems in their use as a feed-
stuff (Tierney, 1972b). Also, before a complete picture
of the hydrophytes potential in a biological nutrient
removal system can be formed, the efficiency of nutrient
removal needs to be obtained as well. Indirect estimates,
such as the pounds of P per person per year, do not fully
provide the answer. The measurement of the quantity of P
and N entering a system, the amount existing, the quantity
residing in the hydrophytes and in the sediments provide
the minimum data on which the efficiency of aquatic plants
as nutrient sinks can be ascertained. Though the value of
harvesting aquatic plants to reduce the ambient dissolved
nutrient loads of wastewater discharges is unresolved, one
ancillary aspect of harvesting appears beneficial. In
existing pond systems loaded with nuisance growths of
naturally occurring vascular macrophytes, annual removal

by mechanical harvesting would reduce the rate of autumnal

46

organic sedimentation and, thereby, reduce the rate of
filling in of the ponds. This would effectively extend

the life expectancy of the ponds.

CONCLUSIONS

1. The wastewater chemical melieu was the more

favorable environment for the growth of E. canadensis.

 

The doubling time was about 4-fold faster for this species
in the Fowlerville wastewater pond than in the catchment
pond. The lower primary productivity rates and maximum

standing crops achieved by the wastewater«grown E; cana-

 

densis is due to reduced spring vegetative density and
autumnal shifts in light intensity and ambient water
temperature. The effect was to alter the intensity of
environmental resistance significantly in the wastewater
site compared to seasonal variations in the catchment
pond.

2. The size of the standing crop at the study
sites was not related to the ambient soluble-P or

nitrate'N concentrations. Tissue levels in E. canadensis

 

and E. demersum were above the critical concentration
level established by Gerloff and Krombholz (1966). Appar-
ently, tissue levels as high as those observed here indi-
cate that neither the environmental level of phosphorus

or nitrogen is limiting to aquatic macrophyte growth.

47

3. Though the size of the standing crop did not

reflect the soluble-P concentration of the study sites,

 

phosphorus tissue accrual by E. demersum and E. canadensis
was related to the ambient solubleeP concentrations among
the study sites. The tissue phosphorus level increased

in the submerged vegetation in a parallel fashion to
environmental levels of solub1e«P encountered among the
three study sites. This site difference in tissue-P con-
tent of the plants is attributed to the different environ‘
mental conditions and not to genetic uniqueness of the
spatially separated populations.

4. Phosphorus levels in the submerged aquatic
plants were 2 to lOefold higher than values reported for
aquatic plants grown in natural lakes and streams. Nitro-
gen levels were similar to the reported range for sub-
merged hydrophytes.

5. E. canadensis and E. demersum did not demon—

 

strate any difference in phOSphorus accumulation within
the same site. However, nitrogen accrual tended to be
higher in E. demersum. Presumably, interspecific genetic
differences in phosphorus uptake and accumulation are
absent while existence of such differences are suggested
for nitrogen accrual.

6. On the basis of the Ca:P ratios, the submerged
macrophytes appear suitable for use as an animal fodder.

However, no information on the content of tissue nitrate-N

48

is available. The possibility of deleterious accumula-
tions of nitrate-N should be considered.

7. Temporal variation in tissue-P content was
fairly constant in the catchment pond plants while more
variability was observed in the wastewater populations.
Where percentage tissue-P values remained relatively
uniform, the rate of phosphorus uptake is considered
approximately similar to the rate of biomass synthesis
up to and including the achievement of maximum standing
crop. Percentage tissuevN varied widely and no seasonal
pattern emerged.

8. The quantities of phosphorus and nitrogen
harvestable under a one‘crop format in the Fowlerville
wastewater pond was ~16 and ~58 lbs/acre, respectively.
These quantities could be elevated by increasing the
number of cuttings and the size of the standing crops
at time of harvest. Removal efficiencies were estimated
by calculating the annual per person discharge of P and
N in domestic sewage. Under the harvesting conditions of
this study, macrophyte removal only equalled the P and N
annual discharge of 7 people. Extensive land area would
be required to serve a community of only 2,000 inhabitants
effectively. The problem of disposal of the harvested

plants may also be troublesome.

REFERENCES CITED

REFERENCES CITED

Adams, Franklin 8.; David R. MacKenzie; Herbert Cole,
Jr.; and Marilyn W. Price. 1971. The influence
of nutrient pollution levels upon element consti-
tution and morphology of Elodea canadensis rich.
in Mich. Environ. Pollut. 1:285-298.

 

Anonymous. 1969. Standard Methods for the Examination
of Water and Wastewater. Am. Publ. Heal. Assoc.,
Washington, D.C., 870 p.

Bartsch, A. F. 1972. Nutrients and eutrophication-
prospects and options for the future, pp. 297-300.
A panel discussion. In: Likens, G. E. (ed.),
Nutrients and Eutrophication: The Limiting
Nutrient Controversy. Amer. Soc. Limnol. Oceano,
Inc., Allen Press, Inc., Lawrence, Kansas.

Bowen, H. J. M. 1966. Trace Elements in Biochemistry.
Academic Press, New York, 235 p.

Boyd, Claude E. 1967. Some aspects of aquatic plant
ecology. Reservoir Fishery Resources Symposium.
Athens, Georgia, 114-129 p.

Boyd, Claude E. 1968a. Evaluation of some common aqua-
tic weeds as possible feedstuffs. Hyacinth
Control Journal. 7:26-27.

Boyd, Claude E. 1968b. Fresh«water plants: a potential
source of protein. Economic Botany. 22, 4:359-
368.

Boyd, Claude E. 1969. Production, mineral nutrient
absorption, and biochemical assimilation by
Justicia americana and Alternanthmxiphiloxeroides.
Arch. HydrobioIi 66:139-160.

 

 

Boyd, Claude. 1970a. Production, mineral accumulation
and pigment concentrations in T ha latifolia
and Scripus americanus. Ecology SI, 2:285«290.

 

Boyd, Claude E. 1970b. Chemical analyses of some
vascular aquatic plants. Arch. Hydrobiol. 67,
1:78-85.

49

50

Boyd, Claude E. and Lloyd W. Hess. 1970. Factors in-
fluencing shoot production and mineral nutrient
levels in Typha latifolia. Ecology 51,2:296-300.

 

Boyd, Claude E. 1971. Vascular aquatic plants for
mineral nutrient removal from polluted waters.
Economic Botany. 24:95—103.

Caines, L. A. 1965. The phosphorus content of some
aquatic macrophytes with special reference to
seasonal fluctuations and applications of phos‘
phate fertilizers. Hydrobiologia. 25:289'301.

Commoner, Barry. 1971. The Closing Circle: Nature,
Man and Technology. A. A. Knopf Inc., New York.
326 p.

Derr, P. F. 1972. Nutrients and eutrophicationvprospects
and options for the future, pp. 300*303. A panel
discussion. In: G. E. Likens (ed.), Nutrients
and Eutrophication: The Limiting-Nutrient Con-
torversy. Amer. Soc. Limnol. Oceano. Inc.,

Allen Press Inc., Lawrence, Kansas.

Edmondson, W. T. 1972. Nutrients and phytoplankton in
lake Washington, pp. 172*193. In: G. E. Likens
(ed.), Nutrients and Eutrophication: The Limiting-
Nutrient Controversy. Amer. Soc. Limnol. Oceano.
Inc., Allen Press Inc., Lawrence, Kansas.

Forsberg, Curt. 1960. Subaquatic macrovegetation in
Osbysjdn. Djursholm. Oikos. 11:183-199.

Galston, Arthur W. 1964. The Life of the Green Plant.
Prentice-Hall Inc., Englewood Cliffs, N. J. 118.

Gerloff, G. C. and P. H. Krombholz. 1966. Tissue analy-
sis as a measure of nutrient availability for the
growth of angiosperm aquatic plants. Limnol.
Oceanogr. 11:629-537.

Gortner, R. A. 1934. Lake vegetation as a possible
source of forage. Science. 80:531-533.

Harper, Horace J. and Daniel, Harley A. 1934. Chemical
composition of certain aquatic plants. Botanical
Gazette. 96:186-189.

51

Howe, L. H. and Holley, C. W. 1969. Comparisons of
mercury (II) chloride and sulfuric acid as pre-
servatives for nitrogen forms in water samples.
Environ. Sci. Tech. 3:478e48l.

Jenkings, D. and Medsker, L. L. 1964. Brucine method
for determination of nitrate in ocean, estuarine,
and fresh waters. Anal. Chem. 36:3, 610.

Larson, Charles W. 1972. Personal Communication. Meme
ber American Institute of Real Estate Appraisers.
Lansing, Michigan.

Lindstrom, H. V. and W. M. Sandstrom. 1939. III. The
nature of the carbohydrates of species of Elodea,
Myriophyllum, Ceratophyllum, RuEpia and Ranuncqus.
U. Minn. Agri. Exp. Statibn Tec . ull. ' - .

 

 

Little, E. C. 8. (ed.). 1968. Handbook of Utilization
of Aquatic Plants. FAO, Rome. 120 p.

Lueck, C. H. and D. F. Boltz. 1956. Spectrophotometric
study of modified heteropoly blue method for
phosphorus. Anal. Chem. 28:1168-1171.

Merrell, John C., Jr.; William F. Jopling; Roderick F.
Bott; Albert Katko; and Herbert E. Pintler.
1967. The Santee Recreation Project, Santee,
California. U. S. Department Interior, FWPCA.
Cincinnati, Ohio. 67 p.

McNabb, Clarence D.; Dennis P. Tierney; and Stanley R.
Kosek. 1972. The uptake of phosphorus by
Ceratophyllum Demersum growing in wastewater.
Inst. Water Research Tech. Report No. 24, Mich.
State Univ., East Lansing. 23 p.

 

McNabb, Clarence D. and Dennis P. Tierney. 1972.
Growth and mineral accumulation of submersed
vascular hydrophytes in pleioeutrophic environs.
Inst. Water Research Tech. Report No. 26, Mich.
State Univ., East Lansing. 33 p.

Nelson, Wesley J. and Palmer, Leroy S. 1939. Nutritive
value and chemical composition of certain fresh‘
water plants of Minnesota. U. Minn. Agri. Exp.
Station Tech. Bull. 136:4'34.

Odum, Eugene P. 1971. Fundamentals of Ecology. W. B.
Saunders Co., Philadelphia. 557 p.

52

Oglesby, R. T. 1969. Effects of controlled nutrient
dilution on the eutrophication of a lake, pp.
483-493. In: Eutrophication: Causes, Conse-
quences, Correctives. National Academy of
Science. Washington, D.C.

Pennypacker, Stanley P.; William E. Sopper and Louis T.
Kardos. 1967. Renovation of wastewater effluent
by irrigation of forest land. Jour. Water Pollu-
tion Control Federation. 39:285-296. ‘

Perl, G. 1935. Zur Kenntnis der wahren Sonnenstrahlung
in verschiedenen geographischen Breiten. In:
Hutchinson, G. Evelyn. 1957. A Treatise on
Limnology, Vol. 1. John Wiley and Sons, Inc.,
Londan, p. 371.

Price, C. A. 1970. Molecular Approaches to Plant
Physiology. McGraw-Hill Co., Inc., New York.
387 p.

Rickey, G. F. and A. W. Avens. 1955. Photometric deter-
mination of total phosphorus in feeding stuffs
and fertilizers. Assoc. Off. Agr. Chem. 38:
898-903.

Riemer, D. N. and S. J. Toth. 1968. A survey of the
chemical composition of aquatic plants in New
Jersey. New Jersey Agri. Exp. Stat. Tech. Bull.
820:14.

Rohlich, Gerard A. 1969. Engineering aspects of nutrient
removal, pp. 371-382. In: Eutrophication:
Causes, Consequences, Correctives. National
Academy of Science, Washington, D.C.

Rohlich, G. A. and P. D. Uttormark. 1972. Wastewater
treatment and eutrophication, pp. 231-245. In
G. E. Likens (ed.), Nutrients and Eutrophication:
The Limiting-Nutrient Controversy. Amer. Soc.
Limnol. Oceano. Inc., Allen Press Inc., Lawrence,
Kansas.

Saitoh, Munekatsu; Kazuki Narita and Sigeo Isikawa. 1970.
Photosynthetic nature of some aquatic plants in
relation to temperature. Bot. Mag. Tokyo. 83:
16‘12 a

Sawyer, C. N. 1944. Biological engineering in sewage
treatment. Sewage Works J. 16:925-935.

53

Schuette, H. A. and Alder, H. 1927. Notes on the
chemical composition of some of the larger
aquatic plants of Lake Mendota II. Vallisneria

or Potamo eton. Trans. Wis. Acad. SEi., Arts,
Letters. 23:249-254.

Schuette, H. A. and Alder, H. 1929. Notes on the
chemical composition of some of the larger aquatic
plants of Lake Mendota III. Castolia adorata
and Najas flexilis. Trans. Wis. Acad. Sci.,

Arts, Letters. 24:135-140.

 

 

 

Siegel, Sidney. 1956. Nonparametric statistics for
the behavioral sciences. McGraw-Hill Company,
New York. 303 p.

Sokal, Robert R. and F. James Rohlf. 1969. Biometry.
W. H. Freeman and Co., San Francisco. 759 p.

Stake, E. 1967. Higher vegetation and nitrogen in a
rivulet in central Sweden. Hydrologie. 29, 1:
107-124.

Stake, E. 1968. Higher vegetation and phosphorus in a
small stream in central Sweden. Hydrologie.
30, 2:353-373.

Tierney, Dennis P. 1972a. Some aspects of the ecology
of naturally occurring populations of submerged
vascular hydrophytes in municipal wastewater
lagoons. II. Trace elements accumulation.
Ph.D. dissertation, Michigan State University,
East Lansing, Michigan.

Tierney, Dennis P. 1972b. Some aspects of the ecology
of naturally occurring populations of submerged
vascular hydrophytes in municipal wastewater
lagoons. III. Potential use as a feedstuff
and soil conditioner. Ph.D. dissertation, Michi-
gan State University, East Lansing, Michigan.

Thompson, T. W. 1972. Control of water milfoil in
Wisconsin. Paper presented Nat. Meeting of the
Weed Sci. Scoeity of America. St. Louis, Mo.
February 8-9, 9 p.

Tucker, J. M.; D. R. Cordy; L. J. Berry; W. A. Harvey;
and T. C. Fuller. 1961. Nitrate poisoning in
livestock. Calif. Agric. Exp. Stat. Ext. Ser-
vice, Univ. Calif. Circular 506. 9 p.

S4

Underwood, E. J. 1966. The Mineral Nutrition of
Livestock. FAO, Central Press Ltd., Aberdeen,
Great Britain. 224 p.

VanVuran, J. P. J. 1948. Soil Fertility and Sewage.
Dover Publi. Inc., New York. 236 p.

Wadelin, C. and Mellow, M. G. 1953. Extraction of
heteropoly acids. Anal. Chem. 25:1168-1173.

Westlake, D. F. 1963. Comparisons of Plant Produc-
tivity. Biol. Rev. 38:385-425.

Wick, Arne N. and W. M. Sandstrom. 1939. II. The nitro-
gen distribution of Elodea canadensis. U. Minn.
Agri. Exp. Station. Tech. BuII. 136:35-42.

PART 2

TRACE ELEMENT ACCUMULATION

INTRODUCTION

Interspecific differences in mineral accumulation
are a well recognized phenomenon in terrestrial floral
investigations (Mitchell 1945, Hill et a1. 1953, Beeson.
et a1. 1955, Schfitte 1964, Dykeman and Desousa 1965).
Equally documented is intraspecific variation in mineral
accumulation from different areas (Beeson et al. 1955,
Schfitte 1964, Dykeman and Desousa 1965). Interspecific
mineral accumulation among aquatic macrOphytes should be
observable since their evolutionary origins are terres-
trial (Sculthorpe, 1967). Observable intraspecific
differences should also be demonstrable, as inorganic
mineral distribution is not quantitively homogenous among
aquatic habitats (Hutchinson, 1957). The mineral inputs
to watercourses usually reflect the "land-uses" of the
region as well as the natural geochemical weathering proc-
esses (K0pp and Kroner, 1970).

Boyd (1968, 1970a, 1970b) reports interspecific
mineral accumulation in aquatic vascular plants from a
single site. Other studies by Boyd (1968, 1969) have
described intraspecific variation observable in an aquatic
vascular plant's inorganic mineral composition when grown

in different environments. Additional studies by Harper

55

56

and Daniel (1934), Gerloff and Krombholz (1966), Allensby
(1966) and Anderson et a1. (1966) present evidence of both
processes for emergent and submerged vascular plants.

All the above mentioned studies have usually con-
sidered nitrogen and phosphorus uptake as well as the other
macronutrients. Only a. few (for example, Boyd 1969, 1970b)
have considered the trace element.composition; and then,
generally only those elements thought essential to plant
nutrition. Additionally, the research occurred in aquatic
enviornments relatively devoid of the direct impingement
of man's activities. Information also needs to be gathered
on the temporal dynamics of trace element accumulation in
aquatic macrOphytes. As Boyd (1970a) points out, little is
known regarding the seasonal periodicity in nutrient uptake
or the relationship between dry matter production and nutri-
ent accumulation.

Data on the accumulation of eight trace elements
(Cd, Co, Ni, Pb, Cu, Zn, Fe, Mn) was gathered on two

naturally occurring submerged macrophytes, Elodea canadensis

 

and Ceratophyllum demersum, growing in municipal sewage-

 

oxidation ponds and a small catchment pond not receiving
domestic effluent. The latter site is located in the
immediate environs of a moderately large industrial city
while the former served two small mid-Michigan towns.

Three of the trace elements studies (Pb, Ni, Cd) are

thought to be non-essential for plant nutrition, but when

57

accumulated in moderate quantities are relatively toxic to
plants and animals (Bowen, 1966). In addition, their dis-
tribution in the environment is often largely a by-product
of industrial processes (Browning 1969, Kopp and Kroner
1970). In light of the recent discovery of mercury's dis-
tribution in the environment and ecologic stress (D'Itri,
1971), collection of information on other heavy metal dis-
tributions in the biota is pertinant to developing a better
understanding of inorganic mineral flow in the structure

and function of ecosystems.

MATERIALS AND METHODS

The study sites consisted of two wastewater ponds,
circa 2 and 10 hectares in area, serving the communities of
Fowlerville and Belding, Michigan and a 8 hectare catchment
pond located in the environs of Lansing, Michigan. Speci-
mens for trace element analyses were collected from

naturally occurring populations of E. canadensis and E.

 

demersum. Collections were obtained approximately biweekly
throughout the summer and fall of 1970. All samples were
collected by hand, washed in the pond water to remove
debris, placed in plastic bags and stored on ice enroute

to the laboratory. Whole plants were washed in deionized
water and dried in a forced draft oven at 80°C for 24

hours. Lime incrustations and other adhesions were not

S8

removed. Dry weight was recorded and plant material was
ground in a Wiley mill adapted for trace element analyses
using a 40 mesh screen. Samples were combined for a given
date and stored under dessication.

A wet ashing procedure (Gorsuch, 1959) of HNO3 and
HClO4 acid was employed to digest-the plant tissue in a
Bethge distillation apparatus made of Vycor-ware glass
(D'Itri, 1970). Glassware was cleaned according to direc-
tions of Thies (1957) and Mizuike (1965) for trace element
studies. Subsequent to digestion, samples were stored in
polyethylene vessels (Mizuike, 1965). Approximately 0.8
to 1.0 grams of dry plant material was used per digestion.
Triplicate determinations were made for each sampling date.
Trace elements were determined using a Jarrell-Ash 800

atomic absorption spectrOphotometer.

RESULTS AND DISCUSSION

Interspecific and Site Variation
in Mineral Accural

 

 

Interspecific variation in trace element content of
the vascular hydrophytes was observed in this study. While
the mean tissue accumulation of Cd, Co, Ni, Cu, Zn and Fe

was similar in E. canadensis and E. demersum growing in the

 

catchment pond, the latter species exhibited significantly

higher levels of Pb and Mn. Co-occurring populations of

59

QE.canadensisand E. demersum growing in the chemical regime

 

of the Fowlerville wastewater pond contained similar quan-
tities of Cd, Co, Fe and Mn; but Cu and Zn levels were

significantly greater in E. demersum, while E. canadensis

 

had higher levels of Ni and Pb. Thus interspecific varia-
tion is striking. It is displayed in Table 1. The degree
of similarity or difference in net quantities of trace
elements accumulated by the two species is treated sta-
tistically in Table 2 (Siegel, 1956). The plants were
apparently growing under identical nutrient conditions,
so the variation in tissue levels represent species dif-
ferences in trace element accumulation. This generality
is confirmed in the work of Boyd (1970a, 1970b), who found
species differences in emergents, submerged and floating
leaf plants with respect to macro- and microelement accural.
The work of Gerloff and Krombholz (1966) shows differential
macronutrient accumulation as well.

The habitat in which a particular species exists
effects the uptake of trace elements. Significant site
differences in tissue content are observable for all trace

elements, except Cu, in E. canadensis removed from Fowler-

 

ville compared to plants from the catchment pond. Similarly,
levels of Cd, Ni, Cu, Zn, Fe and Mn in E. demersum were
significantly higher in plants grown in the Fowlerville
wastewater location compared to the airport catchment pond

(Tables 1 and 2). Boyd (1969), Harper and Daniel (1934),

60

.wcom HmoEAUHeue

 

 

 

 

 

fivHV Heal Away meal mafia mafia mafia Heal
omfiaommH eaawae man OHH m.4a4.~e 4.Ham.mH R.oam.w m.oam.m H.oa~.H meuefimm
flofio meal mal meal flag mafia mafia HOHU
AOHHHAOH emHHmNNH oaao.ao m.NHo.mN a.Haw.mN a.oao.m m.oao.m H.oaa.fi apaoaaa<
“mac nwfiv mafia “may Away mafia mafia “HHS
oamammmm CNNamaON m.mao.om o.eao.ma o.oao.o~ e.oam.HH m.oao.o m.oa4.~ mHHH>aonoa
ESmHoEop .m
fimfiv Away Away Amao mafia AmHV Away mmfiv
Hoaamo wNHaamNH m.mao.fim o.mao.om A.HH@.HN e.oao.m m.oao.a m.oaa.~ auaoaaa<
mmfiv heav nmfiv AmHV “may mmHV Away Away
mmaawweN ommamamfi m.aae.fia m.mao.AN m.Hao.4N o.oam.NH 4.oam.e m.oao.m afifiasaoazoa
mHmcopmnmo .m
a: am am so ea Hz co co seam
ucoanHmcoo

 

 

.QoHo wchcmHm Ezeaxme

 

 

.mHmocpcmHmm :H mmmzflmcm mo Honszz
Mo poHHom mcwm3HopH was ou.m: unounou msmmwp name
no women 533V ESmHoEop .u use mHmcowmcmo .m :H mucoEoHo woman mo AuHucmno

.mmm H EM\m:V

.H oanmh

61

..pcom Hcoegopmo HHOQHHm,.:mmwaon .mchqu u < mam .pMom amazom .cmemUHE .mchHom u m
.pcom amazon .cmmHnon .oHHH>HoH30m u m .EomHoEop .o u u .mHmcopmcmo .m u mo

 

.Hcopcoo ucoaoflo oomHu :H
oucoammme 0: mo mHmmAHomx: Has: mo :oHuuonoH Ho museumouum mo Ho>mH mnma<n

.pcom amazom-co: uzoenoumue

 

 

Noo.o ~oo.o oa.o mo.o ca.o Noo.o Noo.o Noo.o weaeHom -

m A a m A a m n a m v a m u a m A a m A a m A a mHHH>amHzom
oa.o Noo.o Noo.o Noo.o No.o OH.o mo.o No.o Shoaafl< -

< A m < v m < A m < A m < v m < u a < v a < v m meueaom
Noo.o No.o No.0 No.0 No.o No.0 oa.o mo.o “Hoaau< -

< A m < A a < A a < A a < v a < A a < u a < A a QHHH>aoazoa

EdeoEop .o
Noo.o mo.o mo.o ou.o OH.o Noo.o Noo.o No.o Saoaaa< -
< A a < A a < A a < u a < A a < A m < A a < A a 0H3H>aoazom

 

mHmcopmcmo .m
ZOHH<ADZDUU< mHHm

 

 

Ne.o oa.o OH.o oa.o ou.o oH.o oa.o oa.o
u v m o u m o u m o u m o v m u." m o u m o u m mpaoaaa<
oa.o OH.o mo.o No.o No.0 oa.o oa.o ,BOH.o
u u m o u m u v m o v m u A m u A m u - m u - om mHHH>amfizoa
onH<Sazeuu< uHmHumammmezH
:2 ma eN nu ma Hz co co spam

 

 

.mpmoe a Hoeuaez-eeazv .mouam bemaommae ea
moHoomm some mo cOHumHsssoom HeamcoHoMMlepcm owmm m cwaszlcoHumHSESOUm
unoEoHo comp» onHoommHoqu EdeoEop .u paw mHmcopmcmo .m mo mHmAHmG< .N manmh

62

Anderson et a1. (1966) and Adams et a1. (1971) also report
site variation in mineral accumulations in other aquatic
plants. Presumably, the genetic composition of the dif-
ferent populations of a species is identical, so the
differences in tissue level represent different environ-
mental trace element conditions. However, the possible
existence.of ecotypes or locally distinct genotypes needs
further consideration (Anderson et a1. 1966).

While comparisons above are for a catchment and
wastewater pond, site differences exist between naturally
occurring pOpulations of E. demersum taken from the two
wastewater facilities as well. All trace elements, except
Pb and Cu, are significantly higher in samples of E.
demersum removed from the Fowlerville pond (Table 2).
Apparently, this disparity reflects a difference in the
quantity of trace elements in the municipalities waste or
in the quality of the physical-chemical conditions of each
pond. Trace element accumulation in aquatic macrophytes
from waters not receiving municipal effluent can also be
higher than from wastewater ponds. E. demersum sampled
from the catchment pond contained significantly higher
concentrations of Cd, Co and Fe than populations grown
in the Belding wastewater site. Pb tissue content was.
highest in E. demersum from the non-sewage site compared
to samples obtained from both wastewater sites (Table l

and 2).

63

The location of the catchment pond in close prox-
imity to planes, highways and industrial activity suggests
a plausible explanation for the high trace.element content
of the submerged vascular plants. It was abutting the air-
port landing area and within a mile of a major highway.
Browning (1969) and Kopp and Kroner (1970) have noted that
many of the trace elements distribution innature are mainly
the result of man's activity. Atmospheric precipitation
contains Pb, Zn, Cu, Fe, Mn and Ni (Lazrus et a1. 1970).
Emission particles from industrial and vehicle combustion
processes plus decomposition of metal components through
age and wear are distributed over a geographic area by rain
and wind currents (Anomous.1966, Carroll 1969). Deposition
of Pb and other trace elements on the soil and plant life
is greatest near highways (Page and Ganje 1970, Lagerwerff
and Specht 1970, Dedolph et al. 1970). Based, then, on
these sources of trace elements and their patterns of dis-
tribution, the accumulation of these elements in the
catchment pond appears reasonable. Whether ponds more
remotely located from urban-industrial centers contain
plants with a significantly lower trace element content
needs to be determined. However, such localities may
already be lacking since many of the trace elements are
considered to be ubiquitous in global distribution
(Browning, 1969). Any differences in accumulation may be

too small to be significant relative to the other

64

environmental variables that also control plant mineral
uptake and accumulation.

The relative abundance of each trace element in
the aquatic plants can be seen in Table l. The elements
are ranked from least to most abundant. Cobalt is present
in the smallest amounts while iron and manganese are the
most abundant. This ranking shows essentially no inter-

specific preference or site variation.

Temporal Dynamics of Mineral Uppake

 

Absolute net accrual of ash and individual trace
elements on a.square meter basis usually increased up to
the maximum standing crop in both species at all sites
(Tables 3 - 7). The largest quantities accumulated in

populations with the largest plant biomass. E. canadensis

 

and E. demersum growing in the airport catchment pond had
the highest standing crops of 410 and 75 gm-mz, respec-
tively (Tierney, 1972a). Boyd (1969, 1970b) observed a
similar mineral accrual pattern in four emergent aquatic
vascular plants.

Percentage values of ash and microelements did

not uniformly decrease in E. canadensis and E. demersum

 

during the periods up to and including maximum standing
crop. The individual tissue constituent varied widely

over these periods and no general pattern is clearly

6S

 

 

 

 

 

 

 

.pswwoz khan .Qouu wchcwum Eseflxmrm

0.00A 0.0NA 0.50A 0.00 N.00 5.0A 0.Nm A~05000

A.0 A 0.A A.0 A00.A 4.0 A 0.5 A.0 A A.A N0.0 A 0.A A.0 A 0.A A.0 A 0.A fiAaa0 0:
4.04 5.00 0.54 0.0m A.Nm 0.0A 0.4N Ame\me0

5.5AA 0.000 0.00A m.500 0.00AA A.A5m 4.00A 0.004 0.5NA 5.004 N.~5A 0.A5AA 4.N0A 4.455 Asaa0 05
0.0 0.5 0.0 A.0 5.0 0.A 4.0 AN05000

0.0 A 0.00A A.4 A 0.0AA A.A A 0.N5 4.5 A 4.50 A.0 A A.A0 5.0 A 5.00A 4.A A 0.0AA 5:050 0n
04.0 00.0 0.4 5.0 0.0 0.0 5.N A~e\me0

A.A A A.5 0.0 A 4.4 0.5 A m.4m A.5 A 4.00 0.4 A N.4m 0.N A 5.00 0.0 A 0.00 Aeaa0 so
A.A 0.A N.A 0.A 0.A 0.0 5.0 “N05000

5.0 A 4.0A 0.0 A 0.4A 0.A A 0.4A 0.H A 5.5A 4.0 A 0.0A ~.A A 5.0m A.N A 0.AN Aeaa0 00
0.004 N.050 0.005 0.000 0.040 0.AmA 5.00m MNE\AA0

4.0 A A.5 4.0 A 4.0 4.A A 0.0 5.0 A 5.0 0.A A 0.5 0.0 A 0.AA 0.0 A N.0 flea00 A2
N.A0N 0.405 0.00N 0.5Am A.A4N N.04 0.mmA “N050A0

N.0 A ~.4 N.0 A 4.0 0.0 A 0.0 0.0 A m.m 5.0 A 0.0 0.0 A N.4 0.0 A 0.4 Aeaa0 00
0.50 0.05 4.50 0.00A 0.05 0.5A N.44 Am05040

A.0 A 0.A N.0 A A.A ~.0 A N.A N.0 A ~.A A.0 A 0.A A.0 A 0.A H.0 A 4.A A0000 00
A.0 N.AA 0.01 0.0A 0.NA 0.A N.0 A~e\m0

A.N A 5.0A 0.A A 4.0A 0.A A 0.0A 5.0 A N.5A 0.N A 0.5A A.N A 0.0A 0.0 A H.0A fl00 0A4

ESonEop EDHwNLNOpreu
0-0A 40-0 1-0 00A-0 00-5 00-0 0-0 AcaauAAmcoo
open
.flum A :mozv .Ucoa HoumZoummz mcwpflom EH CZOHM Eamumaop .w :H Hopes ohmsem you

mucoSuHumcoo omozu mo mu::050 ecu mucoEoHo oomhu mo pad-Egg paw 5mm wo :oHuHmOQEoo mumucooamd

.n magma

'- >

66

.uanoz >09

..moHo mcfivcmum ESEmezm

 

 

 

 

 

 

0.00 0.00 0.05 0.00 0.00 0.0 0055000

0.0 A 5.0 A 0.0 0.0 A 0.0 0.0 A 0.0 A 0.0 0.0 A 0.0 00000 00
0.4 0.0 0.0 0.0 0.0 0.0 “005000

0.00A 0.000 A 0.40 0.0 A 0.05 4.5 A 0.000 A 0.00 0.0 A 4.05 AEAAV 00
00.0 0.0 0.0 0.0 0.0 0.0 0005000

0.0 A 0.40 A 0.04 0.00A 5.00 0.0 A 0.05 A 0.00 0.0 A 0.00 00000 :0
0.005 0.454 4.005 0.000 0.004 4.00 n005000

4.0 A 4.00 A 0.00 0.0 A 0.00 0.0 A 4.00 A 0.00 4.0 A 0.00 AEAAU 00
0.040 0.000 5.004 0.000 0.000 0.0 ~055000

0.0 A 0.0 A 4.0 0.0 A 0.00 0.0 A 4.00 A 5.40 0.0 A 0.00 maaa0 02
0.400 0.400 0.000 0.000 0.040 0.0 0005000

0.0 A 0.4 A 0.0 4.0 A 4.0 0.0 A 4.0 A 0.5 4.0 A 0.5 meaa0 00
0.040 0.04 0.000 0.04 4.00 0.0 ”005000

0.0 A 0.4 A 5.0 0.0 A 0.0 0.0 A 0.0 A 0.0 0.0 A 4.0 00000 00
0.0 0.0 0.0 5.0 0.0 0.0 “00500

0.0 A 5.50 A 5.00 0.0 A 5.40 0.0 5.00 A 0.00 4.0 A00.00 fi00 00<

EdeoEmp Enaaxnmoumnou
040-0 00-0 00-0 00-0 0-0 00-5 00000000000
open
.flmm H :mozv .pcog Houmzoummz o000>06030m

 

:0 mcHzoum samHoEop EsHfixnmduwnmu :0 Hopes onscm Hog mucoSuHumcoo @0030
we muczosm paw mucoEoHo oomHH mo pan-Ema cam #00 mo :oHuHmomEoo ommucoopom

.4 00000

67

.0nm003 Sum

.mohu mchcmum Esswwam

 

 

 

 

 

 

 

 

a
0.000 0.00 . 0.00 0.00 0.00 00s\000
0.0 A 0.0 0.0 A 0.0 0.0 A 0.0 0.0 A 0.0 4.0 A 0.0 00000 00
0.0 0.0 4.0 0.0 5.0 0055000
0.00A 0.000 0.0 A 0.00 0.0 A 0.00 0.5 A 4.05 5.0 A 0.00 00000 00
0.0500 0.005 5.005 0.440 0.000 “005000
0.0 A 5.00 0.0 A 0.00 0.0 A 5.00 5.00A 4.50 5.40A 0.00 meaa0 00
0.0040 0.0000 0.000 0.000 0.000 “055000
0.0 A 0.00 0.5 A 0.50 0.0 A 0.00 0.0 A 0.00 0.0 A 0.00 00000 00
0.0040 0.005 0.504 0.00 0.040 0005000
0.0 A 0.00 0.0 A 4.00 0.0 A 0.00 0.0 A 0.00 5.0 A 0.40 00000 02
0.400 0.000 0.000 0.44 0.45 0005000
0.0 A 5.4 0.0 A 4.0 5.0 A 4.5 5.0 A 0.0 0.0 A 0.5 A5000 00
0.000 0.000 0.00 0.00 4.00 0005000
4.0 A 0.0 4.0 A 0.0 0.0 A 5.0 4.0 A 0.4 0.0 A 0.0 00000 00
4.00 0.00 0.0 0.0 0.0 500500
0.0 A 0.40 0.0 A 4.00 0.0 A 0.50 0.0 A 0.00 0.0 A00.00 000 00<
mHmcmpmqmo mopofim
«40.0 00-0 00-0 00-0 0-0 00000000000
mama
.mmm H :mon .pcoa 0000360003 m000>06030m
m :0 mcHonw mHmcopmemo empon :0 Hopes 000560 Hem 00:030wumcoo 000:0
mo mandoEm use manoEoHo ou000 mo pan-Ema paw :00 mo :oHHHmomEoo ommuqoouom .m oHQmH

68

 

 

 

 

 

 

.0cm003 0093 .mouo wc0pcmum Ede0xmzw
5.000 0.000 0.050 4.004 0.000 0.440 0.00 4.00 00e\0e0
0.0 A 0.0 0.0 A 0.0 0.0 A 0.0 0.0 A 0.0 0.0 A 4.0 0.0 A 0.0 0.0 A 0.0 4.0 A 0.0 A0000 00
0.04 0 000 0.40 0.000 4.00 4.00 0.00 0.04 fl005000
0.04A 0.004 0.000A 0.000 0.00A 0.504 0.000A 0.045 0.000A 0.440 0.00A 0.000 0.000A 0.050 0.000A 0.000 A5000 0:
0.0 0.0 0.0 0.00 0.5 0.0 0.0 5.0
0.0 A 0.00 0.4 A 0.04 0.0 A 5.40 0.0 A 0.44 0.0 A 0.54 0.00A 0.40 0.0 A 0.00 0.40 A 0.00 00000 00
0.0 0.0 0.0 0.50 0.4 0.0 0.0 0.0 00E\0e0
0.0 A 0.0 0.0 A 0.0 5.0 A 5.00 5.4 A 0.04 0.0 A 0.00 0.0 A 0.50 5.0 A 0.04 0.0 A 0.00 00000 00
5.0 0.4 .0.0 0.0 0.0 4.0 0.0 ,.4.0. fl0050e0
4.0 A 0.00 0.0 A 0.40 0.0 A 0.00 0.0 A 0.00 0.0 A 0.00 0.4 A 0.00 0.0 A 0.00 0.0 A 0.50 A0000 00
0.0 0.0 0.0 5.0 0.0 0.0 05.0 00.0 0005050
0.0 A 0.00 0.0 A 5.00 0.0 A 4.5 0.0 A 0.0 0.0 A 0.0 4.0 A 0.00 4.0 A 0.00 5.0 A 0.0 A0000 02
4.500 0.5000 0.0000 0.4050 0.000 0.400 0.000 0.000 0005000
5.0 A 0.0 0.0 A 0.0 0.0 A 0.0 0.0 A 0.4 0.0 A 0.4 0.0 A 0.0 0.0 A 4.4 0.0 A 0.0 05000 00
0.400 4.000 0.000 0.000 0.000 0.000 0.040 4.05 0005000
0.0 A 0.0 0.0 A 0.0 0.0 A 5.0 0.0 A 0.0 0.0 A 0.0 4.0 A 0.0 4.0 A 0.4 4.0 A 0.0 AE000 00
0.00 0.04 4.00 0.50 0.50 0.50 5.00 0.00 0005000
0.0 A 0.40 0.0 A 5.00 0.0 A 0.00 0.0 A 0.00 0.0 A 0.00 0.0 A 0.00 4.0 A 5.00 0.0 A00.00 000 000
mflmcowmcmu MDVOHQ
0-00 0-00 00-0 000-0 50-5 0-5 00-0 00-0 00000000000
0009
.A22 mo mm cmozv .pcoa 0:05:0000 0000000 :0 :300m mwmmmmmmmm .M c0 00005

000300 00m 00:0:00umcoo 000:0 mo mucsoEm 0:0 00:05000 00000 mo wag-Ema 0:0 :00 mo

cofiuwmomeoo 0mmucoo0md

.o 00200

69

.0AM003 00m

.5000 M500500m 5550x020

 

 

 

 

 

 

 

a
0.0 0.05 0.00 5.00 0.0 0005000

4.0 A 0.0 0.0 A 0.0 0.0 A 0.0 00.0 A 0.0 00.0 A 0.0 00000 0:
0.0 0.40 0.00 0.00 5.0 0005000

0.0 A 0.0 0.0 A 0.0 0.0 A 0.0 0.0 A 0.0 0.0 A 0.0 00000 00
0.0 0.0 0.0 0.0 0.0 0005000

5.00A 5.000 4.4 A 0.04 0.40A 0.00 0.0 A 0.05 4.0 A 0.50 00000 00
0.40 4.0050 0.400 0.054 0.00 0005000

5.0 A 0.00 0.0 A 0.00 4.0 A 0.00 0.0 A 4.00 0.4 A 0.00 00000 00
0.05 5.5500 0.000 0.044 4.00 0005000

0.0 A 0.00 0.0 A 0.00 0.0 A 0.00 0.0 A 0.00 0.0 A 4.00 00000 00
0.00 0.000 0.000 0.000 0.00 0005000

0.0 A 0.0 0.0 A 0.5 0.0 A 0.0 0.0 A 0.0 0.0 A 0.00 00000 02
0.00 0.000 0.04 0.50 0.00 0005000

0.0 A 0.0 0.0 A 4.4 0.0 A 4.5 0.0 A 0.0 0.0 A 0.4 00000 00
0.0 0.000 0.50 5.40 0.0 0005000

0.0 A 0.0 0.0 A 0.0 0.0 A 4.0 0.0 A 0.0 0.0 A 0.0 00000 00
00.0 0.00 4.0 0.0 04.0 0005000

4.0 A 0.00 5.0 A 0.40 0.50 5.0 A 0.00 00.00 000 000

55000500 550005mmu000u
0-00 000-0 00-0 50-5 00-0 00000000000
0009
I .nmm A 50020 .0500 050500000
0005000 50 53000 55000500 .0 50 00005 000500 009 005050000500 000:0
mo 0055050 050 00505000 00000 00 050-555 050 :00 mo 50000005500 0m0050u00m .5 00005

70

discernable (Tables 3 - 7). For example, lead and copper
levels in g. demersum from the Belding pond decreased while
the plant aged. However, lead remained constant and copper
increased in Q. demersum removed from the catchment pond.
Boyd (1969, 1970b) found the percentage values of ash and
macronutrients decreased in all emergent species as the
plants aged. However, the trace element dynamics (Fe, Mn,
Zn, Cu) did not as clearly reflect the mineral decline
pattern observed with the macronutrients (Boyd, 1969).
In this regard, the emergent and submerged plants trace
element patterns are in agreement.

In contrast to the declining macronutrient levels
observed in the emergent species (Boyd, 1969, 1970b),
macronutrient (P and N) percentage tissue content in E.

canadensis and Q. demersum remained relatively constant as

 

the plants aged (Tierney, 1972a). Presumably, the per-
centage decline of macronutrients with growth is a plant
response to low environmental levels, such that the uptake
of nutrients does not match the rate of growth. That some
uptake occurs is observed by the increasing absolute quan-
tities of elements per square meter. If the above assump-
tion is tenable, the similarity between trace element
accumulation in emergent and submerged aquatic plants is
explainable on the basis of the environmental level of
these elements being saturated relative to the plant's

growth rate. The decline in Inacronutrients (P and N) in

71

the emergents and not in the submerged plants seems to indi-
cate the latter are in a comparatively enriched macro-
nutrient regime compared to biomass synthesis.

Though E. canadensis and g. demersum trace element

 

tissue content did not exhibit the general decline up to
maximum standing crop as the emergents, the tissue content
of the individual trace elements did vary; such that the
trace elements net rate of uptake was not always prOpor-
tional to the net dry matter production as measured by the
change in percentage tissue level over time. For example,
the uptake of Cu, Pb, Zn, Fe and Mn by Q. demersum occurring
in the catchment pond was not proportional to net primary

production while Cd, Co and Ni uptake was roughly propor-

 

tional. However, E, canadensis co-occurring with Q.
demersum exhibited net mineral uptakes approximately pro-
portional to net dry matter production for all trace
elements. As Boyd (1969) noted, the standard errors for
microelements are much wider than observed for macro-
elements. Conclusions on temporal uptake are therefore
more difficult to discern precisely.

The trace elements most often accumulated in pro-
portion to net dry matter synthesis irregardless of site
or species were Cd, Co, Ni, and Pb. Only Co is considered
essential for certain plant groups (Price, 1970)._ The
remainder are considered non-essential and relatively

toxic to plants (Sauchelli 1969, Bowen 1966). To date,

72

little is known regarding the mobility of these ions. Sites
of accumulation and distribution of these cations throughout
the plant by translocation and redistribution were not ascer-
tained. Whole plant analysis as performed in this study

did not measure these internal physiologic activities.

The field studies of Boyd (1969, 1970b) and others
with naturally occurring p0pu1ations of vascular aquatic
plants usually terminated subsequent to the date of maximum
standing crop and therefore do not contain information on
mineral dynamics during the "moribund" period of growth.
Trace element net uptake and loss during autumnal decom-

position in E. canadensis and g. demersum reflect seemly

 

selective processes depending on the element and species
considered. For example, 9, demersum accumulated Zn and

Mn in the catchment pond and the Belding pond. Additionally,
Fe was also accumulated in the latter site (Tables 7 and 3).

g. canadensis, however, accumulated Cd, Co, Pb and Fe in

 

the catchment pond (Table 6). Only Fe was accured by-both
species while Cu was preferentially loss by them. No
doubt the flux of trace elements is a complex plante
environment interaction dependent on numerous factors.

One of which is the physiologic age of the plant. The
mineral physiologic processes in the "moribund" stage of
growth differs from earlier periods of growth. Just as
caution must be used when estimating average production

from autumnal terminal biomass (Westlake, 1965), the use

73

of mineral analysis from the ”moribund" phase as.a seasonal

estimate of plant mineral content requires discretion.

Comparative Mineral Accumulation

Relative to Beeson's (1941) extensive analyses of
the trace element content of agriculturally important

plants, the aquatic plants E. canadensis and g, demersum

 

contain significantly greater quantities of trace elements
when expressed as percentage of dry weight. Levels of
cobalt, manganese, nickel, c0pper, iron, and zinc in the
aquatic macrophytes were higher by factors of 30-60, 10-30,
8-20, 5-15, 3-10 and 2-5, respectively. Trace element
data in the studies of Miller (1958), Beeson et a1. (1955),
Beeson and MacDonald (1951), Beeson et al. (1947), Dykeman
and DeSousa (1966), Peck and Walker (1970), Hill et a1.
(1953), Mitchell (1945), Pyatnitskaya (1970) and Babov

et al. (1970) reveal a similar pattern. However, data of
Small (1970), Schauble (1970) and Munson (1970) with agri-
cultural crops reveal a tissue content of zinc and copper
very similar to levels in these aquatic plants. Kehoe

et al. (1933), Pyantnitskaya (1970) and Ter Haar (1970)
observed quantities of lead in edible cr0ps. Generally,
the amounts were 50 to 500 fold lower than in the aquatic
plants. Notable exceptions were the leaf and chaff por—
tions of crops growing near highways. These parts had

levels approximately equal to those in the aquatic plants

74

(Ter Haar 1970, Lagerwerff and Specht 1970, Dedolph et a1.
1970). Lagerwerff and Specht (1970) found tall fescue, blue
grass and orchard grass close to highways to have lead
levels equal to or 2 fold higher than the aquatic plants.
Cadmium, nickel and zinc concentrations in these grasses
were usually 2 to 4 fold, 2 to 6 fold and 4 fold lower than
those in the submerged aquatic plants, respectively.

Cannon (1960) reports the average metal content of
five types of vegetation growing in unmineralized soil. The
data are expressed as percentage of ash rather than per-
centage of plant dry weight. She includes analyses from
all classes of vegetation including the edible herbaceous
plants. The tissue level of cobalt and lead in the sub-
merged plants is 2 to 3 fold higher than in these, while
copper, nickel, manganese and iron values are similar to
or slightly greater than levels in the above ground por—
tions of grasses and herbs. Zinc content of the submerged
aquatic plants is a strikingly 2 to 3 fold lower. Presum-
ably, the-inclusion of many terrestrial plant species
normally not considered and the expression of results on
an ash basis account for the close similarity between the
submerged vascular plants and terrestrial vegetation. The
use of dry weight or ash weight as the basis for calculating
the percentage mineral content may produce striking dif-
ferences. Anomalies in mineral accumulation are often more

pronounced when expressed in the latter form (Cannon, 1960).

75

Comparisons of trace element content on an ash basis needs
consideration as a supplemental measurement in future
studies. It's feasibility as an ecologic measure-requires
further elucidation.

Comparison of trace element quantities observed in

Elodea canadensis and Ceratophyllum demersum from this

 

 

study with other aquatic plant investigations is hampered
by their numerical paucity. Few trace elements have been
considered. In addition to this difficulty, differences
in the type of analysis used, the plant part(s) sampled,
time of sampling, species studied, and variation in local
environmental limiting factors place constraints-on the
interpretation of the data. Bearing this in mind, Nelson
and Palmer (1939) reported iron (4080 ppm) and manganese

(3310 ppm) levels in young green sprigs of E. canadensis

 

while Mayer and Gorham (1951) observed leaf levels of
1320 and 2441 ppm iron and manganese, respectively. The

former authors also found 8.4 ppm c0pper in E. canadensis.

 

McIntosh (1972) noted a median c0pper content of 28 ppm in

whole plant analyses of Blodea nuttallii, while Riemer and

 

Toth (1968) analyzing an Elodea sp. found levels of copper,
zinc, manganese and iron to be 21.5, 119, 4200 and 17200 ppm,
respectively. Compared to Table 1, the iron, manganese and
zinc levels of Riemar and Toth (1968) are higher. The iron

level of Nelson and Palmer (1939) is also greater while

76

Mayer and Gorham (1951) express an intermediate value.
Copper quantities are less or similar for all studies.

Regarding g. demersum, the mean c0pper level of
15.2 ppm (DW) reported by Riemer and Toth (1968) is lower
than values observed here while the zinc content (164 ppm)
is 1.5 to 2.5 times higher. Manganese and iron levels of
2900 and 3000 ppm, respectively, are elevated, especially
the latter (Table l). Boyd (1970a) observed c0pper and
zinc levels in Q. demersum comparable to quantities accu-
mulated in this study. However, manganese and.iron levels
were usually lower, especially manganese. Trace element
values for other aquatic plants span the range found here
as well (Boyd 1969, 1970a, Riemer and Toth 1968, Nelson
and Palmer 1939, Mayer and Gorham 1951).

As far as presently discernable to the author, no
comparative aquatic plant data is available on cobalt
accumulation and the literature is also seemly depauperate
of data on Ni, Cd and Pb. In cultivated rice, the lead,
cadmium and zinc content was 22, 125 and 4700 ppm (ash) in
the polished rice grain. Rice was obtained from a dis-
trict where chronic cadmium poisoning occurred in Japan

(Kobayashi, 1971). Cadmium and zinc levels in g, canadensis

 

and C. demersum were approximately 10 fold lower (~11 and
344 ppm-ash) than rice content. However, lead concentra-
tion is 4 to 5 fold higher' (~115 ppm-ash) than in the rice.

Lead accumulation in rice grains and nonedible portions

77

collected near Crowley, La. was 4 to 500 fold (0.04-5.8
ppm-DW) lower than in the submerged aquatic plants. The
highest quantities residing in the nonedible hulls and
straw (Ter Haar, 1970).

Despite the difficulties in comparing the trace
element concentration of vegetation from different regions
of the biosphere, this type of data is the skeleton of an
evolving body of basic ecologic knowledge on mineral rela-
tionships in vascular plants as well as ecosystem mineral
interfacing. For example, programs designed to use aquatic
vascular vegetation as a mineral removal agent in coupled
aquatic-terrestrial wastewater reclamation projects have
been suggested. Aquatic submerged plants can accumulate
large quantities of lead and cadmium. Cadmium and lead
are cumulative poisons in mammals. Schemes designed to
use these aquatic plants as a domestic animal fodder as
suggested by Boyd (1971) and others require a cautionary

appraisal. This problem is considered by Tierney (1972b).

CONCLUSIONS

1. Elodea canadensis and Ceratophyllum demersum
demonstrated differences in trace metal accumulation within
the same site. This has been ascribed to the genetic dis-
tinctness of each species with regard to mineral uptake and

accural.

78

2. Populations of each species growing in_more than
one habitat exhibited differences in trace element content.
The variation observed is attributed to the different envi-
ronmental conditions at each site.

3. The ranking of trace elements from least to
most abundant in the tissue (ppm) is similar in the sub-
merged plants irregardless of species or site. Cobalt was
present in the smallest amounts and manganese usually the
largest quantities.

4. Accumulation of trace elements by submerged
aquatic vascular plants is a dynamic process, not a static
one, with regard to temporal patterns. Seasonal estimates
of plant trace element content must consider this factor.
For example, values based on autumnal observations are not
necessarily the same as ones obtained in earlier periods
of the growth curve.

5. The relationship between rate of net dry matter
production and net trace element uptake is complex. In some
cases, uptake of the element was approximately proportional
to primary production as measured by change in percentage
tissue levels over time. The elements most often accumué-
lated in proportion to dry matter synthesis were cadmium,
cobalt, nickel and lead. No one element increased proFT
portionally with net primary production in either species.

in all study sites.

79

6. Trace element levels in the submerged aquatic
plants are usually several-fold higher than in terrestrial
plants of agricultural importance on a dry weight basis.
Lead, cobalt, manganese, nickel and c0pper have the highest
concentrations relative to land plants. When the comparison
is on an ash basis, the difference between the aquatic and
terrestrial flora decreases. This method apparently accounts
for the differences in ash content of terrestrial and aquatic.
submerged plants. The latter having approximately 15-25 per-
cent of the dry weight biomass in the ash component while
the former usually has only one-half to one-third that
amount.

7. Trace element levels in Elodea and Ceratophyllum

 

fall within a range found in other studies of these species.
Other aquatic vascular plants had tissue levels ranging
about the values found here. The relationship between
tissue level of an element and environmental quantity of
it is still not clear. Critical field and laboratory
studies are needed to elucidate the important physical
and chemical processes which mediate the uptake and accural
of trace elements.

8. The accumulation of cadmium, lead and nickel in
aquatic plants needs further study. These elements are

toxic to plants and animals in relatively small quantities.

REFERENCES CITED

REFERENCES CITED

Adams, Franklin 8., David R. Mackenzie, Herbert Cole, Jr.,
and Marilyn W. Price. 1971. The influence of
nutrient pollution levels upon element constitution
and morphology of Elodea canadensis. Rich. in
Michx. Environ. PoIIu t. 1:285-298.

Allenby, K. G. 1966. The manganese and calcium content of
some aquatic plants and the water in which they
grow. Hydrobiologia. 27:498-500.

Anderson, Richard R., Brown, Russell G., and Rappleye,.
Robert D. 1966. The mineral content of M rio-
phyllum s icatum L. in relation to its aquatic
env1ronment. EcoIogy. 47. 84- 86.

Anonymous. 1969. Cleaning our Environment--The Chemical
Basis for Action. A Report.American Chemical
Society. Amer. Chem. Soc., Washington D.C. 248p.

Babov, D. M. and Muromtseva, A. A.’ 1970. Trace element
composition of some vegetables grown in chernozem
soil of Odessa region. Vop. Pitan. 29, 1:81-3.
(Russ.) In: Chem. Abst. 75.

Beeson, K. C. 1941. The mineral composition of crops with
particular reference to the-soils in which they were
grown. U.S.D.A. Misc. Publ. 369:1-164.

Beeson, K. C., Louise Gray, and Mary B. Adams. 1947. The
absorption of mineral elements by forage plants.
I. The phosphorus, cobalt, manganese and copper
content of some common grasses. Jour. Amer. Soc.
Agron. 39:356-362.

Beeson, K. C., and H. A. MacDonald. 1951. Absorption of
mineral elements by forage plants. II. The rela-
tion of stage of growth to the micro-nutrient
element content of Timothy and some legumes. Agron.

Jour. 43:589-593.
Beeson, K. C., Lazar, Victor A. , and Boyce, Stephen G.

1955. Some plant accumulators of the micro- -nutrient
elements. Ecology. 36. 155- 156.

80

81

Boyd, Claude E. 1968. Some aspects of aquatic plant
ecology,IuL 114-129. In: Symposium on Reservoir

Fishery Resources. University of Georgia Press,
Athens.

Boyd, C. E. 1969. Production, mineral nutrient absorption
and biochemical assimilation by Justicia americana
and Alternanthera philoxeroides. Af7h. Hydrobiol.
66, 27139-160.

 

Boyd, C. E. 1970a. Chemical analyses of some vascular
aquatic plants. Arch. Hydrobiol. 65, 1:78-85.

Boyd, C. E. 1970b. Production, mineral accumulation and
pigment concentrations in Typha latifolia and
Scirpus americanus. Ecology. 51, 2:285-290.

 

 

Bowen, H. J. M. 1966. Trace Elements in Biochemistry.
Academic Press, New York. 235p.

Browning, Ethel. 1969. Toxicity of Industrial Metals.
Butterworth and Co., London, England. 361p.

Cannon, Helen L. 1960. Botanical prospecting for ore
deposits. Science. 132:591-598.

Carroll, Robert E. 1969. Trace element pollution of air,
pp. 227-232. In: Delbert D. Hemphill (Ed.),
Trace Substances in Environmental Health III.
Univ. of Missouri, Columbia.

Dedolph, Richard, Gary Ter Haar, Richard Holtzman, and
Henry Lucas, Jr. 1970. Sources of lead in

perennial ryegrass and radishes. Environ. Sci.
Tech. 4, 3:217-223.

D'Itri, Frank M. 1970. Personal Communication.

D'Itri, Frank M. 1971. The Environmental Mercury Problem.
Tech. Report No. 12. Institute of Water Research,
Michigan State University, East Lansing, Michigan.

Dykeman, W. R., and DeSousa, A. S. 1966. Natural
mechanisms of copper tolerance in a copper swamp
forest. Canadian Jour. of Botany. 44:871-878.

Gerloff, G. C., and Krumbholz, P. H. 1966. Tissue
analysis as a measure of-nutrient availability

for the growth of angiosperm aquatic plants.
Limnol. Oceanogr. 11:529-537.

82

Gorsuch, T. T. 1959. Radiochemical investigations on the
recovery for analysis of trace elements in organic
and biological materials. Analyst. 84:135-173.

Harper, Horace J., and Daniel, Harley A. 1934. Chemical
composition of certain aquatic plants. Botanical
Gazette. 96:186-189.

Hill, A. Clyde, Toth, Stephen J., and Bear, Firman E.
1953. Cobalt status of New Jersey soils and forage
plants and factors affecting the cobalt content of
plants. Soil Science. 76:273-284.

Hutchinson, G. Evelyn. 1957. A Treatise on Limnology,
Vol. 1. John Wiley and Sons Inc., London. 1001p.

Kehoe, R. A., Thamann,-F., and J. Cholak. 1933. On the y”
normal absorption and excretion of lead. I. Lead "

absorption and excretion in primitive life. 'Jour.
Industrial Hyg. 15:257.

Kobayashi, J. 1970. Relation between the "itai-itai"
disease and the pollution of river water by cadmium
from a mine. Paper presented 5th Internat. Water
Poll. Research Conf. July-Aug., 1970. San
Francisco. 7p.

Kopp, John F., and Kroner, Robert C. 1970. Trace Metals
in Waters of the United States. U.S.D.I. Fed.
Water Pollution Control Adm., Cincinnati. 29p.

Lagerwerff, J. V., and A. W. Specht. 1970. Contamination
of roadside soil and vegetation with cadmium,
nickel, lead and zinc. Environ. Sci. Tech. 4,
7:583-585.

'Lazrus, Allan L., Elizabeth Lorange, and James P. Lodge, Jr.
1970. Lead and other metal ions in United States
precipitation. Environ. Sci. Tech. 4, 1:55-58.

Mayer, A. M., and E. Gorham. 1951. The iron and manganese
content of plants present in the-natural vegetation
of the English lake district. Annuals of Botany.
15, 58:247-263.

McIntosh, Allen. 1972. Personal Communication.
Miller, D. F. 1958. Composition of Cereal Grains and

Forages. Nat. Acad. Sci., Nat. Res. Council,
Publ. 585. Washington, D.C. 659p.

83

Mitchell, R. L. 1945. Cobalt and nickel in soils and
plants. Soil Science. 60:63-70.

Mizuike, A. 1965. Separations and preconcentrations,
pp. 103-153. In: Morrison, G. A. (Ed.), Trace
Analysis, Physical Methods. Interscience Publishers,
New York.

Munson, Robert D. 1970. Plant analysis: varietal and
other considerations,IuL 84-105. In: Greer,
Francis (Ed.), Proceedings From a Symposium on
Plant Analysis. Internat. Min. Chem. Corp., Skokie,
Illinois”

Nelson, Wesley J., and Palmer, Leroy S. 1939. Nutritive
value and chemical composition of certain fresh-
water plants of Minnesota. U. Minn. Agri. Exp.
Stat. Tech. Bull. 136. 33p.

Page, A. L., and T. J. Ganje. 1970. Accumulations of
lead in soils for regions of high and low motor
vehicle traffic density. Environ. Sci. Tech. 4,
7:583-585.

Peck, T. R., and W. M. Walker. 1970. Comparison of plant
analysis data at high and low corn yields,Iun 128-
135. In: Greer, Francis (Ed.), Proceedings From
a Symposium on Plant Analysis. Internat. Min.
Chem. Corp., Skokie, Illinois.

Price, C. A. 1970. Molecular Approaches to Plant
Physiology. McGraw-Hill Co., Inc., New York. 387p.

Pyatnitskaya, L. K. 1970. Levels of some trace elements
in vegetables and fruits of the Sarator region.
Vop. Pitan. 29, 1:83-5. (Russ.) In: Chem. Abst.
75.

Riemer, D. N., and S. J. Toth. 1968. A survey of the
chemical composition of aquatic plants in New
Jersey. New Jersey Agri. Exp. Stat. Tech. Bull.
820: 14p.

Sauchelli, Vincent. 1969. Trace Elements in Agriculture.
Van Nostrand Reinhold Co., New York. 242p.

Schauble, C. E. 1970. Problems with plant analysis,
pp. 27-38. In: Greer, Francis (Ed.), Proceedings
From a Symposium on Plant Analysis. Internat.
Min. Chem. Corp., Skokie, Illinois.

84

Schfitte, Karl H. 1964. The Biology of the Trace Elements.
Crosby Lockwood and Son Ltd., London. 228p.)

Sculthorpe, C. D. 1967. The Biology of Aquatic Vascular
Plants. Edward Arnold Ltd., London. 597p.

Siegel, Sidney. 1956. Nonparametric Statistics for the
Behavioral Sciences. McGraw-Hill Co., Inc.,
New York. 303p.

Small, H. 6., Jr. 1970. Plant analysis experience with
soybeans, peanuts and cotton,;nu 136-144. In:
Greer, Francis (Ed.), Proceedings From 3 Symposium
on Plant Analysis. Internat. Min. Chem. Corp.,
Skokie, Illinois.

Ter Haar, Gary. 1970. Air as a source of lead in edible
crops. Environ. Sci. Tech. 4, 3:226-229.

Thiers, Ralph E. 1957. Contamination in trace element
analysis and its control, pp. 273-335. In:
Click, D. (Ed.), Methods of Biochemical Analysis,
Vol. 5. Interscience Publ., New York.

Tierney, Dennis P. 1972a. Some aspects of the ecology of
naturally occurring populations of submerged
vascular hydrophytes in municipal wastewater
lagoons. I. Primary productivity and phosphorus-
nitrogen accumulation. Ph.D. dissertation,
Michigan State University, East Lansing, Michigan.

Tierney, Dennis P. 1972b. Some aspects of the ecology of
naturally occurring populations of submerged
vascular hydrophytes in municipal wastewater
lagoons. III. Potential use as a feedstuff and
soil conditioner. Ph.D. dissertation, Michigan
State University, East Lansing, Michigan.

Westlake, D. F. 1965. Basic data on aquatic macrophytes,
pp. 231-248. In: C. R. Goldman (Ed.), Primary
Productivity in Aquatic Environments. U. of
Calif. Press, Berkeley.

PART 3'

POTENTIAL USE AS A FEEDSTUFF AND SOIL CONDITIONER

INTRODUCTION

Harvesting of vascular hydrophytes has been one
mechanism proposed for.nutrient removal in eutrophic water-
ways (Livermore and Wunderlich, 1969). Such plant removal
is often initially stimulated by nuisance growths which
reduce the functional as well as aesthetic role of the
water. Sculthorpe (1967), Little (1968) and Holm et al.
(1969) have reviewed the problems incurred world-wide when
luxuriant growths of aquatic plants have occurred. Re-
garding the potential use of harvested aquatic plants,
Gortner (1934), Mrsic (1936), Nelson and Palmer (1939),
and more recently, Bailey (1965), Boyd (1968a, 1968b,
1969) and several authors in Little (1968) have presented
evidence, experimental and observational, that indicate
aquatic plants are often nutritionally suitable as a com-
ponent in animal feed or as a fertilizer. Specifically,

the nutritional characteristics of Elodea canadensis and

 

Ceratophyllum demersum have been reported by Gortner

 

(1934), Nelson and Palmer (1939) and Boyd (1968). Addi-
tionally, Boyd (1968b, 1970) has noted that some aquatic,
plants have large quantities of trace minerals and could

be used as mineral supplements.

85

86

Boyd (1968a, 1968b, 1969, 1970) and Holm et a1.
(1969) have considered the question of economic feasibility
in harvesting aquatic macrophytes. It is generally held
that it is presently not competitive with conventional
forage cr0ps in the developed nations. A project devel-
oped by the Greater Marshall Industries of Marshall, Texas
and funded by the Area Redevelopment Administration of the
U.S. Department of Commerce attempted to harvest and
process nuisance submerged macrophytes on an economically
sound basis (Lange, 1965). The project was abandoned as
unsound due to an unusually dry year which reduced the
water level and spoiled the plants (Lange, 1971). How-
ever, removal of obnoxious plants is beneficial to the
economic life of recreation-oriented communities situated
on or near enriched shallow lakes (Thompson, 1972).

Stimulation of vascular plant growth in terres-
trial species is partially controlled by mineral nutrition
as is aquatic plant growth. However, luxuriant growth of
the former in an agricultural setting is deemed beneficial
and desirable, while such growth in the aquatic-situated
species is generally spurned as a nuisance. A vast cadre
of scientifically-trained individuals have developed agri-
cultural practices, such as fertilization, conducive to
high yields and quality forage and food crops. Tradition-
ally, soil conditioning has consisted of applying various

quantities of animal and terrestrial plant residues to the

87

soil as well as inorganic minerals. Ashlander (1958) has
reviewed the relative merits of organic and inorganic
enrichment of depleted soils to enhance yield. Schfitte
(1964) and others have noted the naturally occurring trace
element imbalances in soils throughout the world, while
Thacker and Beeson (1958) described the occurrence of min-
eral deficiencies and toxicities in domestic herbivores.
Sauchelli (1969) has reviewed the importance of trace
elements in agriculture as well. The transfer of har-
vested nuisance aquatic plants to terrestrial agricultural
settings as a rich trace element soil conditioner or dom-
estic feedstuff may represent a novel method to better

meet the societal approved needs and uses of each sector.

METHODS AND MATERIALS

Naturally occurring populations of Elodea cana-

 

densis and Ceratophyllum demersum were collected from

 

wastewater ponds and from a catchment pond not receiving
inputs of domestic waste. The plant material was analyzed
for trace element content as well as phosphOrus, nitrogen
and calcium accumulations. Calcium determinations were
performed according to methods reviewed by Elwell and Gidley
(1967). Other procedures for plant collection and analysis

are reported elsewhere (Tierney, 1972a, 1972b).

88

RESULTS AND DISCUSSION

Feasibility of Hydrophytes as a Feedstuff

 

Historically, Gortner (1934) noted that Elodea
served as an excellent food for cattle and swine in Holland
and Germany at the turn of the century. It was equally
acceptable as a silage or fresh. Mrsic (1936) observed
Yugoslavian peasants feeding fresh aquatic plants to cattle.
These empirical observations while confirming that domestic'
livestock will consume aquatic vegetation do not assess the
over-all nutritional value. To functiOn as a valuable
animal feed, plants must possess adequate amounts of pro-
tein, essential amino acids, carbohydrates, fats, crude
fiber, vitamins, macroelements and microelements (Miller
1958, Morrison 1961, Cuthbertson 1969). Examples of im-
paired growth, reproductive failure and death in domestic
livestock due to mineral deficiencies or excesses are
documented (Underwood 1962, Schfitte 1964, Stiles 1961).
Excesses of essential microelements can be toxic to dom-
estic herbivores, such as cows, sheep and horses. For
example, copper, zinc, cobalt, manganese and molybdenum
are some essential trace elements which have been found
to be toxic to animals (Underwood 1962, Cuthbertson 1969).
Table 1 indicates the average trace element content of the
submerged vascular plants. Usually the higher mineral

content occurred in plants growing in the wastewater ponds.

.wcom newspapmuo

.wnom ommzomn

.mouo wnwwamum
Eseflxme mcwwsHucH use cu m: mucoEounmmoE wH on mH no comma ohm mcmoZm

 

89

 

NNo HmH.H Hm ‘HN mN OH m N NHoaHH<

cam.N Nmo.H HN mN mN NH o N mHHH>HonoH
mwmcovmnmu .m

NHN.H NHN.H HN mN ON a m N UHHoQHH<

Hom.H cow NHH m4 NH N N H amnHeHom

HNC.N omm.H Hm NH ¢NI HH 0 N HmHHH>Honom

eanoEow .o

 

:2 on :N nu ma Hz 00 cu :oHHmuoH

 

 

.HHHNHoz
Aha Human mthev .cmmmnumz.mw wnom “coaguumu m use mwcom Houmzoumw3 Eoum
mwmnowmcmo .m paw EDmHoEow .u cw mucoEoHo oomau mo :oHumhpcoocou.mowmpo>< .H oHawh

90

The essential trace elements are present in greater than
adequate quantities for proper growth, but generally below
toxic levels with the exception of Cu and Mn in g, demersum.

Cadmium content in g. demersum and E. canadensis approached

 

the toxic level as well (Table 2). All cases of trace
element accural greater than permissible for normal growth
occurred in populations of the aquatic macrophytes from the
Fowlerville wastewater pond.

The incompleteness of Table 2 indiCates the paucity
of knowledge on either the normal or toxic dietary levels
of most trace elements. Two of the more comprehensive
compilations on mineral composition of forages and cereal
grains only contain data on five trace elements; Co, Cu,

Fe, Mn, Zn (Miller 1958, Morrison 1961). The International

 

Encyclopedia of Food and Nutrition, Vol. 17, on the nutri-
tion of animals of agricultural importance lists only
information on nine trace elements; 1, Mo, F, Se and the
fiVe mentioned above (Cuthbertson, 1969). Beeson (1941)
has information on most of these elements and in addition
nickel. The scarcity of data on the amounts of cadmium,
lead and nickel in feeds is striking. Apparently, the
tissue concentration of Cd in the submerged hydrophytes

is only slightly higher than in many land plants (~l ppm)
while the Ni content is up to 35 fold greater than terres-
trial plants (~0.35 ppm). The Pb level as well is usually

several-fold higher in the aquatic plants (Tierney, 1972b).

91

.NomH..eoozwoees .momH .HHHm

 

 

: u

.oomH .nozomw .momH .nomuponnusuu

.momH .gomuwonapaum .momH .aommHop

.moaH .HmHmanomuoo .momH .nomswmngusum
I: ..u us .- In nu nu mv Gm:
HooN.H A -- Hooo.H A HmNN -- -- -- -- Hzom

« a a
uooo H uooo m uooo N oom -- -- -- -- mmHa
-- -- -- -- -- -- -- -- momhom
-- -- -- «cm A -- -- -- -- OHHHmu
-- -- -- «cm A -- -- -- -- mooam
UHxOH
II II II II II I... ”H NH and:
8mm wow emm eH -- -- -- -- HMom
so A goo A 60m A UN -- -- -- -- m Ha
-- -- -- pm -- -- -- -- mompom
ooH mom mom wOH A mH -- -- -- mHHHmu
was «on New A «m A mH -- -- -- macaw
oum366w<

a: on eN so 00 an Hz cu smHamNHo

 

AugmHoz xup pofiw mx\msv uaospfiumnou

 

 

.mnouaomfiw uflxou can Apzonm Hmsuo: How wonwscop
awe use xuoumo>HH mo umfiw :H mgcosoao oomnp mo :oHumHucoonoo opmafixoham< .N oHan

92

Nickel and lead are accumulated in the bones of some
mammals while cadmium accumulates in the kidney and liver
(Underwood 1962, Browning 1969). Cadmium and lead are con-
sidered cumulative poisons in man (Bowen, 1966). Nickel is
relatively nontoxic to man compared to cadmium and lead
(Underwood 1962, Browning 1969). Presumably, domestic.
livestock ingesting aquatic plants would respond in a simi-
lar fashion as man to these heavy metals. Age, sex, and
health of the particular species as well as daily intake
modify the absolute amount of each element deemed detri-
mental to growth and development.

Accumulations of trace elements in aquatic vascular
plants from relatively large eutrophic lakes may be smaller
than those reported here. The wastewater ponds and the'
catchment pond were essentially a closed system regarding
mineral flow. As the ponds aged, the mineral content would
increase since the input of nutrients was continuous in the
former and dependent on precipitation and surface run-off-
in the latter. The catchment pond lacked an outlet while
the water in the wastewater ponds was discharged twice a
year and from the surface down.t Mineral elements would
tend to accumulate in such systems and recycle between the
water, sediments and plant components. While aquatic
vascular plants harvested from eutrOphic lakes may be

acceptable as animal feedstuff, the use of harvested

aquatic plants growing in wastewater as fodder for

93

agriculturally important animals should be approached cau-
tiously. The possibility of toxic effects due to excessive
levels of trace elements is very clear.

The Feasibilitygof Hydrophytes
as a Soil Conditioner

 

The quantity of trace elements removed by harvesting
the submerged plants is a function of the standing crop and
tissue concentration of the minerals (Tierney 1972a, 1972b).
A one harvest format would remove the largest quantity of
trace elements at maximum standing crop. As Tierney (1972a)
noted, the actual maximum standing crop achieved by the sub-
merged vascular plants in the wastewater ponds during these

studies was relatively low. E. canadensis harvested from

 

the non-sewage catchment pond removed the largest quantity
of trace elements since it represented the highest standing
crop (Table 3). However, the plants grown in the wastewater
ponds tended to contain higher amounts of each trace element
on a per gram basis (Tierney, 1972b). The quantities of
trace elements actually removed ranged from a low of 0.2 gm
for~Cd to 4,639 kg/ha for Fe (Table 3). For comparison
Makarov (1971) reported 7.8 gm/ha for Co, 21 for Cu, 32 for
Zn and 77 for Mn removed by the harvest of winter rye grain
and straw. Potato tuber harvest removed from the soil

11.6 gm/ha of Co, 93 of Cu, 120 of Zn and 264 of Mn. These

quantities are fairly similar to those in Table 3 for the

94

.unmfioz ammhm ou fiasco
wohowfimnou ma unmfioz um: .waHm mfinp :H .pcwwoz p03 we we «UHHU ma pamfioz khan

.vogmwxo-ou anon whoa: fimfimcowmamo .mQ mofiuomm
uanHEow mo mono mnflwawum Essfixma um wohuzooo mafiumo>nmc wo.oswu 039 .msz @090
mnwvcmum Esafixma mo mafia pm unoEon 0:» mo «amazon mammflu :o woumHonmo monaa>m

 

 

UI

o.omm o.nwm o.~m w.mH o.um 0.0 H.m H.H Esmhosoo .
econ owmzom .wcflwHom

 

o.mmH o.ouH o.mH m.~ m.v N.H o.H N.o ESmMOEov .

UI

 

ml

o.wmo.m o.mmo.v o.me o.~m m.00H o.om o.wH N.o mfimnopwcmo .

wqom 9:65:0pmu uhomhw< .mnwmamq

 

-- o.me~ o.H¢ H.n m.¢ m.m o.H ¢.H ESmHoEow .

Ul

 

ml

-- o.NHm.H o.NNH c.mN N.NH o.HH o.m H.N mHmamememu .

unom amazom .oHHH>HoH30m

 

a: on :N as :0 Hz co co AQHuoam

 

ampamwoz And m:\amv acoSHHHmcou

 

 

.amwfiauwz :H Econ unmanuumo m
mam mwnom Houmzoummz =H mnfizohm vo>pmmno mouxnmouoma pompoEQSm
mo mpwEHom pmo>pmn-ono a xn wo>osoh mucoEoHo woman mo xuwucmso .m oHnmh

95

aquatic plants. The difference is due to variation in the
size of the standing crOp at time of harvest and the species
involved.

Schfitte (1964) points out that modern agricultural
techniques improve crop yields and simultaneously remove
more trace elements from the soil than under less produc-
tive practices. For example, Gericke (1957) found that
clover hay removed the largest amounts while potatoes
accumulated the least; quantities of Mn ranged from 2 to
38 mg, Cu from 2 to 9 mg and Co from 2 to 6 mg/kg (DW) of
plant tissue. Table 4 indicates the quantity of each
element removed in a kilogram of aquatic plants harvested
in this study. Based on this and the above information,
the application of the submerged hydrOphytes to the soil
would more than replace the amounts of trace elements
removed by these food and forage crops.

In addition to returning trace elements to the soil,
conditions exist where organic manure is essential., For
example, as Ashlander (1958) points out, soil initially
poor in plant nutrients or depleted in humus content would
be more favorably enriched by a combination of organic and
inorganic fertilizers. The present system of arable farm-
ing tends to decrease the humus content of the soil. The
application of organic residues will re-establish the humus
and aid in preventing future soil deterioration (Ashlander,

1958).

96

 

 

oom.mH OOHAm OQOAH mmv v.5m «.mo n.5H 5.0 m.m N.H EamHoEow aw
ucom ommzom .mcfipHom

omv.um ooo.m -- con m.wHH H.¢H ¢.om m.m m.v H.v Edmhoeow .w

 

omH.nN oom.OH .. oomAH o.HHH “.mH .m.om w.HH n.v o.N mwmzowmcmu .m

waom ommzom .oHHH>HoH30m

 

UI

HNm.NH OOH.m mNH.H mmN.H N.Nm m.Hm N.ON o.N H.N H.H esmmeoe .

 

ml

oo~.om ooo.o Hem vmo.H o.vq o.oe mm.mwlw.m m.v m.H mwmcowmnmu .
econ unoemoumo puomnm< .mnmmcmm

 

mu m :2 mm ,eN so an Hz co co moHumnm

 

mpanmmww\mEWu:ozgfipmaou

 

 

.nmmwmomz am anon unoEmuumo
m paw mucom Houmzopmmz Scum mhmuuom.uom oHnwumo>Hma mgcmHm HMH30mm>
wowhosnsm mo unwfioz xuu EmHmoHHx Hon vo>oEoH mucoEoHo mo mEmeHHHHS .v oHnt

97

Usually, organic fertilizer has consisted of animal
and plant residues. Plant residues are considered very
suitable as humus since the decaying plant would contain
the various plant nutrients in approximately the same pro-
portions as needed for crops. The mineral composition of
animal manure varys according to the animal involved, since
the elements are differentially absorbed and excreted. City
compost has also served as a soil fertilizer. Compared
to the approximate.trace element content of some typical
manures, the trace element level of the harvested sub-
merged plants is intermediate (Table 4). Kick (1962)
found the Cu levels varying from 2 to 200 mg/kg in stable
manure and city compost, while Mn and Zn ranged from 30
to 500 and 1.5 to 2000 mg/kg, respectively. The city com-
post is higher in Zn and Cu than the submerged vascular
plants, while the Mn content of these plants is larger.

The aquatic hydrophytes are, however, trace element en-
riched relative to stable manure.

Good fertilizer usually contains ample quantities
of phosphorus, nitrogen and calcium. Farmyard manure is
less desirable than plant residues since the phosphorus
content of the former is comparatiVely low (Ashlander,
1958). The harvested hydrophytes accumulated large quan-
tities of phosphorus (Table 4). For example, the phosphorus
removed by cropping the maximum standing crop of aquatic

plants amounted to 17 to 32 kg/ha for the three sites

98

(Tierney, 1972a). This represents a phosphorus content

S to 10 fold higher than farmyard manure originating from
livestock (Tierney 1972a, Ashlander 1958). These are
strikingly high values. Comparatively, the quantity of
inorganic phosphorus added to the soil in Sweden and

Belgium during 1953-54 to increase crop production was

only 8:95 and 20 kg/ha, respectively (Sylvan, 1955). Fur-
thermore, the nitrogen content is-4 to 5% of the dry weight
in the aquatic plants (Tierney, 1972a). This compares
favorably with the 5% reported for traditional humus mate-
rial (Ashlander, 1958). Humus also has the ability to
reduce the leaching of nitrates from the soil and tends to
promote favorable~soil structure (Commoner, 1968). An ample
supply of calcium is considered necessary for a fertile soil
(Ashlander, 1958). The aquatic plants content of calcium

is noted in Table 4. The amount returned to the soil during
plant residue decomposition wOuld aid in keeping the acidity
of soil from becoming very low.

Aquatic hydrophytes have the potential as an organic
fertilizer. However, difficulties do exist. The high
moisture content presents problems in harvesting and trans-
porting to the area of use. Some draining seems necessary‘
before application to the soil. The possibility of trace
element accumulation in the soil also needs consideration,
especially regarding cadmium and lead. Normally cadmium

and lead are found in the soil in small quantities

99

(Browning, 1969). The relative availability in the soil to
plants of these and other trace cations is dependent on a.
number of factors (Millar 1955, Robertson 1958).- For
example, cations are more readily available in acid 5011
than in basic soil. Caution must be exercised to prevent
excessive accumulation in the soil or in the plant species

grown on it.

Other Considerations

 

The use of aquatic vascular plants as a supple-
mental protein source needs more consideration. As Boyd
(1970) notes, the leaf protein concentrates from two
emergent aquatic species are similar to cr0p plants. How-
ever, the presence of heavy metals in foliage used for
protein concentrates may be of concern. The possibility
of pathogen transfer from adherent water to domestic
herbivores or into the food and forage crops and the con-
centration of slightly biodegradable and potentially toxic
exotic organic compounds adhering or accumulating in the
submerged hydrophytes requires consideration as well. To
accurately ascertain the role of aquatic hydrophytes in
wastewater recycling programs which are designed to hOpe-
fully minimize the effects of human pertebations on aquatic
and terrestrial ecosystems, a highly coordinated inter-

disciplinary approach will be necessary.

100

CONCLUSIONS

Submerged vascular hydrophytes remove large amounts
of mineral nutrients from ambient water. The harvesting of
nuisance aquatic growths, rather than killing and leaving
in place, aids in reducing the rate of hypereutrophication
in natural waters. The planting and harvesting of managed
crops of aquatic vascular hydrOphytes in wastewater effluents
would remove mineral nutrients prior to their release into
natural waterways. The use of the harvested material as a
humus and soil conditioner appears more favorable than use
as a feedstuff for domestic livestock.- The concentration
of several trace elements approaches the level found toxic
in common herbage fed to livestock.~ Copper and manganese
concentrations were above the toxic level in this study.

The economic value of such operations needs further elucida-
tion. Many elements which were formally localized are now

distributed throughout the environment (Anon., 1969). Basic
data on the mineral composition of present forage and cereal
crops as well as other aquatic-hydrophytes needs to include

a broader spectrum of micronutrients and heavy metals.

REFERENCES CITED

REFERENCES CITED

Anonymous. 1969. Cleaning our Environment: The Chemical

Basis for Action. Amer. Chem. Soc., Washington,
D.C. 245p.

Ashlander, A. 1958. Nutritional requirements of crop
plants,IuL 977-1025. In: W. Ruhland (Ed.),
Encyclopedia of Plant Physiology, Vol. IV.
Springer-Verlag, Berlin. '

Bailey, T. A. 1965. Commercial possibilities of dehy-
drated aquatic plants. 80. Weed Conf. Proc.
18:543-551.

Beeson, K. C. 1941. Mineral composition of crops with
particular reference to the soils in which they

were grown. U.S.D.A. Misc. Publication.
369:1-164.

Bowen, H. J. M. 1966. Trace Elements in Biochemistry.
Academic Press, New York. 235p.

Boyd, C. E. 1968a. Fresh-water plants: A potential
source of protein. Econ. Bot. 22:359-368.

Boyd, C. E. 1968b. Evaluation of some common aquatic
weeds as possible feedstuffs. Hyacinth Control

Boyd, C. E. 1969. The nutritive value of three species
of water weeds. Econ. Bot. 23:123-127.

‘Boyd, C. E. 1970. Vascular aquatic plants for mineral

nutrient removal from polluted waters. Econ.
- Bot.. 24:95-103.

Browning, E. 1969. Toxicity of Industrial Metals.
Butterworth and Co.,.London. 361p.

Chumbley, C. G. 1971. Permissible levels of toxic metals
in sewage used on agricultural land. A.D.A.S.
Advisory Paper 10., Ministry of Agriculture,
Fisheries and Food. London. 7p.

101

102

Commoner, Barry. 1968. Threats to the integrity of the
nitrogen cycle: Nitrogen compounds in soil, water,
atmosphere and precipitation. Paper presented
A.A.A.S., December 26, Dallas, Texas. 16p.

Cuthbertson, Sir David. 1969. The nutrient requirements
of farm livestock 1. Poultry, pp. 1203-1242. In:
International EncyclOpedia of Food and Nutrition,
Vol. 17, Part 2. Pergamon Press, London.

Cuthbertson, Sir David. 1969. The nutrient requirements
of farm livestock 2. Ruminants, pp. 883-920. In:
International EncyclOpedia of Food and Nutrition,
Vol. 17, Part 2. Pergamon Press, London.

Cuthbertson, Sir David. 1969. The nutrient requirements
of farm livestock 3. Pigs, pp.-1096-ll36. In:
International EncyclOpedia of Food and Nutrition,
Vol. 17, Part 2. Pergamon Press, London.

Elwell, W. T., and J. A. F. Gidley. 1967. Atomic-
absorption spectrophotometry. International series
of monographs in analytical chemistry, Vol. 6.
Pergamon Press, London. 140p.

Gericke, S. 1957. Die verorgung von pflanze und tier
mit mikronahrstoffen. In: Schfitte, K. H. 1964.
The Biology of the Trace Elements. Crosby Lockwood
and Son Ltd., London. p. 172.

Gortner, R. A. 1934. Lake vegetation as a possible source
of forage. Science. 80:531-533.

Greenhalgh, J. F. D. 1969. Nutrition of the dairy cow,
pp. 717-770. In: International Encyclopedia of
Food and Nutrition, Vol. 17, Part 2. Pergamon
Press, London.

Hill, F. W. 1969. Poultry nutrition and nutrient require-
ments, pp. 1137-1180. In: International Encyclo-
pedia of Food and Nutrition, Vol. 17, Part 2.
Pergamon Press, London.

Holm, L. C., L. W. Weldon, and R. D. Blackburn. 1969.
Aquatic weeds. Science. 166:699-709.

Kick, H. 1962. Gedanken zur spurenelement versorgung der
Kulturpflanzen. In: Schfitte, K. H. 1964. The
Biology of the Trace Elements. Crosby Lockwood and
Son Ltd., London. p. 172.

103

Lange, S. R. 1965. The control of aquatic plants by com-
mercial harvesting, processing and marketing. So.
Weed Conf. Proc. No. 18:536-540.

Lange, S. R. 1971. Personnal communication (to C. D.
McNabb).

Livermore, D. F., and W. E. Wunderlich. 1969. Mechanical
removal of organic production, pp. 494-519. In:
Eutrophication: Causes, Consequences, Correctives.
Nat. Acad. of Sciences, Washington, D.C.

Little, E. C. S. (Ed.). 1968. Handbook of Utilization of
Aquatic Plants. FAO, Rome. 120p.

Makarov, V. A. 1971. Removal of trace elements with the
harvest of crOps. Zap. Leningrad. Sel'skokhoz.
Inst. 160:23-6. (Russ.) In: Chem. Abst. 76.

Millar, C. E. 1955. Soil Fertility. John Wiley and Sons,
Inc., New York. 423p.

Miller, D. F. 1958. Composition of Cereal Grains and
Forages.‘ Nat. Acad. of Sciences. Nat. Research
Council, Publi. 585. Washington, D.C. 659p..

Morrison, F. B. 1961. Feeds and Feeding, Abridged.
Morrison Publishing Co., Clinton, Iowa.. 685p.

Mrsic, V. 1936. Lake vegetatiOn as a possible source of
forage.’ Science. 83:391-392.

Nelson, Wesley J. and Palmer, Leroy S. 1939. Nutritive
value and chemical composition of certain fresh-
water plants of Minnesota.7 U. Minn. Agri. Exp.
Stat. Tech. Bull. 136. 33p.

Olsson, N. 0., 1969. The nutrition of the horse, pp. 921-
960. In: International Encyclopedia of Food and
Nutrition, Vol. 17, Part 2. Pergamon Press, London.~

Robertson, R. N. 1958. The uptake of minerals, pp. 243-
274. In: Ruhland, W. (Ed.), Encyclopedia of Plant
Physiology, Vol. IV. Springer-verlag, Berlin.

Sauchetti, Vincent. 1969. Trace Elements in Agriculture.
Van Nostrand Reinhold Co., New York. 242p.

Schfitte, Karl H. 1964. The Biology of the Trace Elements.
Crosby Lockwood and Son Ltd., London. 193p.

104

Sculthorpe, C. D. 1967. The Biology of Aquatic Vascular
Plants. Edward Arnold Ltd., London. 610p.

Sylvan, Margarete. 1955. The world supply of fertilizers,
p. 984. In: Ruhland, W. (Ed.), Encyclopedia of
Plant Physiology, Vol. IV. Springer-verlag, Berlin.

Thacker, E. J., and K. C. Beeson. 1958. Occurrence of
mineral deficiencies and toxicities in animals in
the United States and problems of their detection.
Soil Science. 85:87-94.

Thompson, T. W. 1972. Control of water milfoil in
Wisconsin. Paper presented Nat. Meeting of the
Weed Sci. Society of America. St. Louis, Mo.
February 8-9. 9p.

Tierney, Dennis P. 1972a. Some aspects of the ecology of
naturally occurring populations of submerged vascular
hydrophytes in municipal wastewater lagoons. 1.
Primary production and phosphorus-nitrogen accumula-
tion. Ph.D. dissertation, Michigan State University,
East Lansing, Michigan.

Tierney, Dennis P. 1972b. Some aspects of the ecology of
naturally occurring populations of submerged
vascular hydrOphytes in municipal wastewater
lagoons. II. Trace element accumulation. Ph.D.
dissertation, Michigan State University, East
Lansing, Michigan.

Wirklander, L. 1958. The soil, pp. 118-164. In:
W. Ruhland (Ed.), Encyclopedia of Plant Physiology,
Vol. IV. Springer-verlag, Berlin.

"mmmm