. -. -_ ————.——— _‘ ___—________—__—__,, '“YI': .. .... . ‘ ..«H....»r~flw—M_. . a , ~\- --. . V‘... H .. v e, , . .-_.-.‘. . ..-.....y......-..~.k\,\—..‘-..-<-~..._¢. ‘\§‘\\‘““-‘”(Q(”Iowfi UTILIZATION or BENTHIC-DETRITUS INA MARL LAKE Thesis for the Degree of Ph. D. MICHIGAN STATE UNIVERSITY PETER HAMILTON RICH 1970 .Ht‘m‘? .2'..I,3RARY Michigan State University This is to certify that the thesis entitled ‘-'TILIZI1TIC)II OF BEITIEIC DETRITUS IN A I'IIIRL LAKE presented by Peter Hamilton Rich has been accepted towards fulfillment of the requirements for 13h. D . degree in Botany aHIl Plallt Pat hology 241$, LIN Major profisor Date 24 QWLYO 0-169 IIIIIIIII IIIIIIII IIIIIIIIIIIIIIIII 3 1293 00802 4402 ABSTRACT UTILIZATION OF BENTHIC DETRITUS IN A MARL LAKE BY Peter Hamilton Rich The importance of detritus has been demonstrated in estuaries and streams. Similarities between these two lotic situations and small, temperate lakes suggested that detritus may also be important in some lentic situations. In the absence of direct methods of measuring lacustrine detritus, an indirect method was postulated and examined. Stoke's Law implies that the production of lacustrine detritus occurs in the benthos. A preliminary benthic car- bon budget of a southern Michigan marl lake indicates that benthic community productivity is relatively high with re- spect to phytoplankton productivity and is dominated by submersed macrophytes. Benthic community respiration is also higher than expected, but not sufficient to account for all benthic carbon not lost to the permanent sediments. Thus, the utilization of benthic detritus is initially confirmed. UTILIZATION OF BENTHIC DETRITUS IN A MARL LAKE BY Peter Hamilton Rich A THESIS Submitted to Michigan State University in partial fulfillment of the requirements for the degree of DOCTOR OF PHILOSOPHY Department of Botany and Plant Pathology 1970 ACKNOWLEDGMENTS I wish to thank my committee, Dr. Robert G. Wetzel (Chairman), Dr. Stephen N. Stephenson, Dr. Brian Moss, and Dr. Kenneth W. Cummins, for their consideration and criti- cal advice. I also appreciate their attention to the interdisciplinary needs of my program. Their responsive- ness made possible the maximum realization of my goals. I am particularly grateful to Dr. Wetzel for the painstaking guidance and effort that was necessary to develop my tenta- tive ideas into a sound and practical research project. Financial support was supplied from ABC Contract #AT(ll-l)-1599, COO-1599-3l and NSF GB 6538 awarded to Dr. Wetzel, and from an NSF Intermediate Predoctoral Fellowship awarded to the author. Support from NSF Grant GB-15665 to Dr. Lauff, gt El. Coherent Area Research Project in Freshwater Ecosystems is also acknowledged. Dr. George H. Lauff aided the logistic support of my research and in manuscript preparation. I gratefully acknowledge his contribution of the core sampler design used for the benthic respiration measurements. Dr.'s Donald J. Hall and Theodore Crovello furthered the inter- pretations of the analyses of variance. Dr. Robert P. ii McIntosh criticized the manuscript thoroughly and very constructively. The staff and students of KBS provided a stimulating environment which contributed much to this thesis and to my professional development. The greater part of this constructive interaction occurred in the course of regular, informal seminars initiated and frequently hosted by Dr. Wetzel at his home. Mr. Arthur Wiest provided tools, time, and materials unstintingly and frequently from his own re- sources. The sediment trap data were obtained jointly with Dr. Michael C. Miller. My wife, Nancy, performed or checked many of the calculations, including the macrOphyte planimetry. Nancy and my son, Jonathan, have been most patient and forgiving during three neglectful years. iii TABLE OF CONTENTS Page LIST OF TABLES . . . . . . . . . . . . vi LIST OF FIGURES O O O O O O O O O O O O Vii Chapter I 0 INTRODUCTION 0 O O O O O O O O O 1 A. Introduction . . . . . . . . l B 0 Objectives 0 O O O O I O O O 5 C O MethOds O O O O O 0 O O O O 5 D. Lawrence Lake . . . . . . . . 12 II. THE DISTRIBUTION AND PRODUCTIVITY OF SUBMERSED MACROPHYTES . . . . . . . 18 A. Introduction . . . . . . . . 18 B I MethOds I O O O O O O O O O 20 C. Results . . . . . . . . . . 23 l. Biomass . . . . . . . . 23 2. Productivity . . . . . . 37 3. Marl Removal . . . . . . 41 III. THE SEDIMENTS . . . . . . . . . . 43 A. sediment Traps O I O O O O O O 43 B. Sediment Core Samples . . . . . 48 C. Permanent Sedimentation. . . . . 54 IV. BENTHIC RESPIRATION . . . . . . . . 56 A. Introduction . . . . . . . . 56 B. Methods . . . . . . . . . . 57 C. Results . . . . . . . . . . 62 V 0 CONCLUSIONS 0 O O O O O O O O O O 7 0 iv Page LITERATURE CITED 0 O I O O O O O O O O O 71 APPENDIX. 0 O O O O O O O O O O O O O 77 LIST OF TABLES Table Page 1. Mean Annual Biomass of Each Submersed Macrophyte Group by Transect. Biomass is Given as g m-2 Ash-free Dry (Organic) Weight . . . . . . . . . . . . . 24 2. Variance Estimates for the Mean Annual Bio- mass of Scir us subterminalis at Important Depths for Each Transect. Biomass is Given as g m-2 Ash-free Dry (Organic) Weight . . . . . . . . . . . . . 25 3. Production Rates for the Aquatic Macrophytes of Lawrence Lake as Ash-free Dry Weight. Maximum Site Figures Equal the Mean of Maximum Sites of the 3 Transects . . . . 40 4. Analysis of Variance of the Sediment Trap Data (Ash-free Dry Weight), 2-way with Replication, Fixed Model . . . . . . . 47 5. Analysis of Variance of the Sediment Core Data (% Ash-free Dry Weight); 4-way with Repli- cation, Fixed Model. . . . . . . . . 53 6. Analysis of Variance of the Benthic Respir- ation Data; 5-way with Replication, Fixed MOdel O O O O O O O O O O O O O 6 8 vi LIST OF FIGURES Figure _ Page 1. Diagrammatic Representation of a Benthic Community Carbon Budget . . . . . . . 8 2. Morphometric Map of Lawrence Lake, Barry County, Michigan, Showing Transects B1 (Organic Mat Shoreline), B2 (Isolated from Shoreline by Dredged Zone), and B3 (Typical Wave-swept Shoreline). . . . . 15 3. MacroPhyte Sampler, Detail of Closing meChanism. O O O O O O O O O O O 22 4. Annual Biomass [g m 2 Ash-free Dry (Organic) Weight] Pattern for the Important Macro- phytic Groups as a Mean Transect Summed with Respect to Depth. Annuals Include Potamogeton spp., Najas flexilis, and Trace Amounts of Several Other Species . . 27 5. Annual Biomass [g m-2 Ash-free Dry (Organic) Weight] Pattern of a Mean Transect Includ- ing Depth Distribution for Scirpus subtenminalis . . . . . . . . . . 29 6. Annual Biomass [g m-2 Ash-free Dry (Organic) Weight] Pattern of a Mean Transect Includ- ing Depth Distribution for Chara (Solid Line) and Annuals (Dashed Line) . . . . 31 7. Distribution of Mean Annual Biomass Over Depth for Each Transect, Including the Atypical Area of Transect 32 (Bz Dredged) Separately. Biomass is given as g m- Ash-free Dry (Organic) Weight . . . . . 35 vii Figure Page 8. Annual Sedimentation Rate [g m-zday"1 Ash- free Dry (Organic) Weight] Pattern at 4 m for Each Transect Including the Atypical Area of Transect B2 (32 Dredged) Where Trap Depth was 3.5 m . . . . . . . . 46 9. Mean Annual Percentage Organic Weight in the Surface Sediments (0—8 cm) Over Depth for Each Transect . . . . . . . . . 50 10. Seasonal Patterns of Percentage Organic Weight of the Surface Sediments of a Mean Transect Over Depth, and Showing Horizon (Not Significant) Fluctuations. . . . . 52 11. CO Accumulation XE! Time for Three Incu- ation Volumes. Variations in 200 m1 Volume Interpreted as Diurnal Effects up to Approximately 30 uM CO . Vertical lines Represent Range of Two Samples. . . . . 61 12. Titration Error and pH Sample Drift During Transportation and Warming. Vertical Lines on Titration Curve Represent 90% Confidence Intervals (n=6) . . . . . . 64 13. Seasonal Patterns of Benthic Respiration as a Mean Transect Over Depth . . . . . . 66 viii I . INTRODUCTION A. Introduction The detritus food chain formulated by Odum and de la Cruz (1963) is based on the balance of primary pro- duction not consumed by macro- or grazer-herbivores. The remaining material becomes the substrate for a complex microflora and -fauna which modifies frequently poor quality or otherwise unavailable material to produce detritus. Detritus, including both the microorganisms and the modified substrate, represents a relatively high quality food source for several terrestrial and aquatic communities. To date, knowledge of the origin and im- portance of detritus in aquatic situations has been limited to estuaries and streams. The best documented estuarine example is the Duplin River behind Sapelo Island, Georgia. The estuary whose vegetation is dominated by an emergent macrophyte, the salt water cord- or marsh-grass (Spartina alterniflora Loisel.), is subjected to vigorous tidal circulation (Ragotskie and Bryson, 1955). The partially decomposed remains of Spartina are suspended and flow into the estu- arine waters where they are utilized by the planktonic community (Starr, 1956; Starr, gt 31., 1957; Ragotskie, 1959). The bacterial decomposition of Spartina produces significant amounts of amino acids and B12 vitamins, and has been postulated as a "transformer" which increases the protein levels of primary organic material for utilization by marine animals (Burkholder and Burkholder, 1956; Burk- holder, 1956). The dominance of the detritus food chain in the marsh community is revealed by estimates that less than 1% of the annual net production of Spartina is con- sumed alive (Smalley, 1960), and that 11% is rapidly con- verted to bacterial biomass (Burkholder and Bornside, 1957). Detritus is important in several types of temperate streams (Teal, 1957; Nelson and Scott, 1962; Hynes, 1963; Ross, 1963; Cummins, 35 31., 1966; Minshall, 1967). Unlike the estuarine situation, allochthonous detrital material in streams originates largely as autumn-shed leaves of riparian trees. Detrital maturation in streams is also associated with protein production by fungi rather than bacteria (Kaushik and Hynes, 1968). Marine and estuarine detriti- vores may assimilate the carbohydrate substrate as well as the microorganisms of detritus (Darnell, 1964). Fox (1950) demonstrated that marine filter-feeders secrete abundant amylase and glycogenase enzymes but insignificant amounts of proteolytic and lipoclastic enzymes. On the other hand, stream insects seem to depend upon the microorganisms (Fredeen, 1960, 1964). In general, far fewer animal phyla are represented in the freshwater sessile community than in its marine counterpart, possibly as a consequence of osmotic stress in larval forms (Hutchinson, 1964). By examining gut contents, Darnell (1964) established the importance of detritus for both invertebrates and vertebrates in a tropical headwater stream, an estuary (Lake Pontchartrain), and the Neuse River in North Carolina. Terrestrial or semiterrestrial plants supplied a major share of the detrital material in all cases. The role of detritus in temperate lakes has not been studied directly, although lakes have several features which suggest the importance of detritus. Like streams, small lakes have high shoreline to surface area ratios, and are influenced by frequently bordering deciduous trees (Goldman, 1961; Szczepanski, 1965). Like salt-marsh estuaries, small lakes frequently have large annual crops of littoral macrOphytes which are not significantly grazed (Westlake, 1965). Filter-feeders dominate the fauna of lakes; however, they are planktonic rather than sessile as in the sea, and consist of microcrustaceans rather than insect larvae found in streams. Probably the only important influence upon detritus common to estuaries and streams which is not shared by lakes is vigorous movement, a feature that imposes several consequences. Because lakes generally do not have signifi- cant outflows, detrital production cannot be estimated directly by filtering techniques such as those used in estuaries (Odum and de la Cruz, 1967). Unfortunately, the small size of lake detritivores makes gut content analysis even more difficult than stream detritivores and the possi- bility of direct estimation of detrital production and utilization in lakes remote. Indirect methods of assaying the diet of zooplankton have suggested a significant detrital fraction but have been both laborious and subject to many assumptions (Nauwerck, 1963). A physical consequence of the lack of circulation in lakes suggests that recently formed ("young") detritus may have a defined flow even if lake water does not. Stoke's Law states that a Sphere of a given density falls through a static, viscous liquid at a rate directly related to the square of its radius. Thus, the decomposition of detritus from large, descrete objects which sink rapidly to small, bacterially modified and colonized fragments (Rodina, 1963) must occur mostly in the benthic community. As the radii of organic particles decrease with decomposition ("maturation") of the detritus, the possibility of resus- pension occurs. While the small amount of turbulence associated with most lakes is not sufficient to prevent fine mineral particles from entering the sediments per- manently, resuspended small particulate organic matter is abundant in the water column when it is completely mixed (Davis, 1968). However, many planktonic filter-feeders of lakes are known to spend daylight hours in or near the sediments and may utilize unsuspended benthic detritus. B. Objectives The initial goal of this investigation was an esti- mate of lacustrine detrital production. Secondarily, some techniques have been tested for further refinement of the initial estimate. This estimate of detrital production is based upon the potential inputs from submersed macrophytes, epiphytes, and phytoplankton, losses due to permanent sedi- mentation, and benthic respiration of CO The secondary 2. testing includes a preliminary search for factors corre- lated with respiration, sedimentation rates measured by sediment traps, and the organic content of the sediment surfaces. C. Methods In the absence of direct methods of estimating the production and utilization of lacustrine detritus, the initial segregation of "young" detritus was accomplished by an indirect method which permitted the estimation of certain parameters of benthic metabolism as a basis for estimating facets of detrital metabolism. Assuming that benthic autotrophy and permanent loss of carbon to the sediments are known, rates of benthic respiration during decomposition ("maturation") of detritus determines the efficiency of detrital production and the ultimate amount of material available. Further, assuming that known inputs of carbon into the benthic community equal known outputs, rates of loss of benthic carbon by respiration and permanent sedimentation estimate the amount of organic carbon leaving the benthos and respired elsewhere by difference ("utilization") (Figure l). The actual form in which the carbon leaves the lake bottom is unspecified and may be as the suspension of detritus into the water, detrital feeding by planktonic invertebrates and verte- brates, the emergence of detritus-feeding insects, or predation at any point in the benthic trophic structure derived from detritus. The sources of error in the above equation are several. Theoretical problems revolve about the definition of organic carbon leaving the benthos as detrital pro- duction or utilization. Detritus suspended into the water column is subject to further respiration which suggests that it does not represent net production, and a large part of the detritus suspended may never be utilized ex- cept by the metabolism of its associated bacteria. On the other hand, predation upon benthic detritivores by plank- tonic animals is not detrital production but, rather, detritivore production. Also, the carbon respired by detritivores is not detrital respiration, but is included in the parameter benthic respiration. Consequently, the loss of organic carbon from the benthos must be defined as either a composite parameter or in terms of communities rather than individuals or p0pulations. Thus, the param- eter is defined as the utilization of the benthic detritus food chain at all levels by the open water community. The .ummcsn cognac wuHCSEEoo canucmn m mo cofiumucmmmummu oaumafimumMHoII.H ousmflm 3325mm mIn. IOmOSZ _ZO_._.m3 HMOflmmuv mm can .AmcoN comcmuc an mcflamuonm Eonm Umumaomflv mm .chaamuosm umE cacmmuov Hm muowmcmne OGHBOQm .cmmflcoflz .mpcsou mnumm .mxmq mocmu3cq mo ace owuumfionmnozll.m mnsmflm 15 Emzow mmwhuf Z_m4<>mwhz_mDOwZOu hwuu 09 o on O 09 as WW MW m mu mcwhwi 24910.2 .>._.ZDOQ >mm m.mn m.mha H.mmm m Hmuoa mamsccd mmmomumco mHHmcHEHmuQSm pommcmua .usmflm3 Acacmmuov who wwumlnmm «IE 0 mm cm>wm ma mmmEon .uommcmnu SQ msonm mumcmouome UmmHmEQSm comm mo mmmEOHQ acsccm cmmzll.a mamme 25 TABLE 2.--Variance estimates for the mean annual biomass of Scirpus subterminalis at important depths for each transect. Biomass is given as g m‘2 ash-free dry (organic) weight. Transect Depth Mean Standard 90% Confidence Error Interval Bl 2 m 196.9 43.9 78.7 3 117.3 34.6 69.5 4 151.2 27.1 53,6 32 2 m 206.3 51.5 84.0 3 184.9 44.1 35,6 4 185.5 29.5 73.9 B3 2 m 172.3 30.2 75,9 3 61.1 28.6 69.9 4 124.1 23.6 64.9 32 3 178.6 34.5 77.7 dredged 26 .mofloomm Hmcuo Hmum>mm mo muccoEc momuu can .mHHwaaw mmhmz ..mmm coummoemuom occaocfl mamsccm .cumwc ou powmmmu nuflz omEEcm pommcmuu some m mm masoum oauwcmouome ucmunomEH ecu How cumuumm Hpnmflo3 ADHcmmHov muc mmHMIcmm m E m. mmmEOHQ HmccchI.v mucmflm 27 S. < <4 m I 080820 I I 2.8.8553 4w I q . u “I"'|-|I “ “ IILI con 00* ssvwom 5) (z-W 000 com v musmwm 28 .mflamcflaumuQSm msmufiom How coflusnfluumfiv gamma mcflwsaocfl pommcmnu :mmE m mo cumuumm Hunmflmz Avacmmuov mHU mmuwunmm m 8 ma mmmEoHn Hmscc4|I.m musmwm (U1) HldElC] 30 .AmcHH wmsmmmv wamsccm mam Amcfia UflHOmv mumco How :oHusQwHumflv sumac maflvsaoca pommcmuu cmmfi M MD cumuumm HunmflmB Acacmmuov muv meMInmm m 8 ma mmmEoHQ Hmsccm||.m musmflm 31 I S o O 69 P- Q 9 Q? . / “ .- MM” ”MW/W M1523.” mag “+£5.51“...— 3 :3 3 In 0 '- N 0') V '0 O N m (W)Hid30 32 Biomass is measured as g m-2 ash-free dry (organic) weight in all cases. Water bulrush (Scirpus subterminalis) was the domi- nant component (76% of all sampled material) of the sub- mersed macrophytic flora at all times of year. Fall and late winter biomass maxima are evident (Figure 4); however, the species is best described as perennial or, more accur- ately, an "evergreen" population. The two annual maxima resulted from dissonant peaks at different depths (Figure 5). The larger fall maximum consisted of a major October peak at 2 m and the terminal stages of a June-August peak at 4 m. The late winter maximum was compounded from minor peaks at 3 and 5 m, the beginning of the summer 4 m peak, and a subsequent minimum created by a marked decrease in the 2 m population in June. A fall peak in the Characeae (16% of all sampled material) was evident within a relatively constant seasonal biomass distribution. Again, this group is best described as an "evergreen" population Figures 4 and 6). The appearance of Nitella flexilis at 7 m (transect B3 only) in July-October and EEEEE at 5 m in September-October was interpreted as an interaction between light, thermal, and carbon stratification. Another species of Nitella is known to be limited by dissolved CO availability above pH 7.3 2 (Smith, 1967). During the month of July, the hydrogen ion concentration at 7 m in the deep water column shifted from about pH 8.3 to pH 8.1 as summer stagnation progressed. 33 The shift may be even greater at the 7 m contour where the lake sediments were in contact with the 7 m water stratum. The disappearance of Nitella and EEEEE at the end of October coincided with fall overturn. The other species of macrophytes, collectively termed annuals (8% of all sampled material), were not sufficiently abundant in the samples to provide reliable estimates of biomass. As a whole, these species (mostly Potamogeton) died in the fall, and their maximum biomass occurred dur- ing the commonly accepted growing season, June through September. Two maxima are apparent in Figure 4 and may also be discerned in Figure 6. The early, deeper peak (4-6 m) was largely of Potamogeton praelongus Wulfen, and the later, shallower peak (3 m) was largely of g. illinoen- sis Morong. Differences among transects, excluding the dredged zone of transect B were not great. Qualitatively, tran- 2! sect B3 differs from the others in the presence of Nitella at 7 m. Only traces of Nitella were found at B2 and no Characeae were ever found below 2 m at transect Bl' Chara was more important in the shallow littoral of transect B1 and the dredged portion of B which are protected from wave 2 action, than at transects B2 and B3 which are exposed. Chara thrived in the presence of Nuphar variegatum at 0.5 m along transect B (The amount of Nuphar was minor 1. and was not included in the biomass or productivity figures; -) it only appeared at transect B1 34 Figure 7.--Distribution of mean annual biomass over depth for each transect, including the atypical area of transect 82 (Bz-dredged) separately. Bio- mass is given as g m“2 ash—free dry (organic) weight. 35 Figure 7 DEPTH (m) OJ---- u. l Uo ‘ ---’— V0 l l 0 d 82 82 \ dredged ‘ — §_. subterminalis _ -— Characeae ---- Annuals l l l l 0 100 200 O 100 200 BIOMASS (g m'2) 36 In all cases, the biomass of Scirpus subterminalis at l m was inversely correlated with the amount of Chara present. With the exception of transect B —dredged, the 2 mean annual biomass of Scirpus subterminalis was highest and consistently close to 200 g In"2 at 2 m. Biomass for this species was also consistently greater at 4 m than at 3 m. Field observations suggest that a springy, fibrous peat stratum at 3 m may have caused the apparent decrease in biomass by either reducing actual colonization by macro- phytes or possibly by reducing the efficiency of the sampler. Some quantitative differences existed between tran- sects with respect to Scirpus subterminalis and Chara. Transect B had more Chara than the other two transects. l The total mean annual biomass for transect B which had 2! the least Chara and the most Scirpus subterminalis, was similar to that of transect Bl' Transect B3 had low amounts of Chara and Scirpus subterminalis, and the lowest total annual biomass. Transect B3 with the wave—swept shallow littoral also had the most pronounced 3 m low. The biomass proportions of transect B -dredged were 2 very different from those of the undisturbed transects. Chara replaced Scirpus subterminalis at 4 m, and repre- sented a much higher proportion of the mean annual biomass. Annuals were poorly represented in the transect. 37 2. Productivity Estimating the productivity of the perennial or "evergreen" species, whose biomass levels remained rela- tively constant throughout the year, was problematical. Generally, estimates of productivity of aquatic macro- phytes in the temperate zone have been based upon measure- ments of biomass increments of emergent and submergent annuals between seed germination and maximum biomass. The simple increment method may be modified to account for the low mortality and losses during the growth period by a turnover rate of 2-20%. The method is confounded in the case of perennials by the lack of clearly defined incre- ments uncomplicated by losses of material persisting from prior growth and by an indeterminate growth period. Borutskii (1950) observed Elodea canadensis to be a perennial in Lake Beloie. A similar observation was made for this species in a marsh of western Lake Erie (Rich, 1966). Based upon estimated losses throughout the year, Borutskii concluded that productivity could be as high as 5 times maximum biomass for this species. Much of the turnover in this case was attributed to damage caused by human interference; a condition not true of Lawrence Lake. Summarizing several other instances where biomass persisted from one growing season to the initiation of the next, Westlake (1965) suggests that annual net production is only 50-80% of maximum biomass in such cases. Thus, 38 productivity given in the literature for submersed perennials in the temperate zone range from 0.5 to 5.0 times maximum biomass. While grazing, damage, and mortality may be negligi- ble or low in the brief period prior to the biomass peak of fast-growing annuals, this assumption is not realistic for perennials maintaining populations throughout a year. Further, a turnover factor established for the observed growth of the "evergreen" group would not account for the annual maintenance of the significant annual minimum bio- mass. In the absence of large storage structures as perennating organs for either Scirpus subterminalis or Chara, maintenance metabolism must be significant at all times of year. Scirpus subterminalis, particularly, is a very fragile plant consisting of a rosette of long (3-5 dm), narrow (1-2 mm), delicate leaves. Chara re- placed Scirpus subterminalis in the shallow littoral probably because it is more resistant to wave action. However, Chara is subject to rapid marl incrustation which makes the plant very brittle. Ice movements have been ob- served which must inflict much damage to the Chara at 0.5 m in winter as well. On the basis of the above observations, the biomass increment method was discarded in favor of two newer con- cepts of turnover estimation. The better documented method, and probably most applicable to the Lawrence Lake flora, is 39 the Allen curve technique (Allen, 1951) as modified for Glyceria maxima and other plants by Mathews and Westlake (1969). The method follows from the observation that Glyceria continuously produces cohorts of leaves and stems which go through annual life cycles. Those cohorts whose growth periods coincide with spring and summer dominate the annual biomass and productivity, but growth and mortality are experienced by all cohorts at all times of year. The most conservative turnover factor of 1.5 for overall annual net production as a function of maximum biomass was selected and applied to the biomass maximum (summer or winter) within each depth population of Scirpus subterminalis and Chara of each transect (Table 3). Both summer and winter peaks were selected and entered into the calculations as two distinct cohorts as an extreme case of this method. The calculation is not warranted in that winter biomass peaks occur at less than l/lO summer light levels (as measured at 2 m; Rich and Wetzel, 1969). Winter accumulation of biomass is inter- preted as resulting from a decrease in the proportion of respiration to photosynthesis. A second calculation method was based on an estimate that aquatic macrophyte productivity based on oxygen pro- duction is approximately twice the net accumulation of the growth period (Westlake, 1965, 1966). Assuming a normal growing period of 4 months, the "evergreen" popu- lations in Lawrence Lake must turnover 3 times to maintain 40 NH mm mmH Hmsccm cmmE Eseflxmz mma oaa mmm ESEmez ANIE my mmmEOHm cmwz Um>ummno mna mmm.m mma mma mom Am xv pocumz mmmEOHm Hmsccd ammz Hmm mmm.ma mad mum mmm Ammucfl3 paw HmEESmV muuonoo N mma mov.m mma mma mom AmmmEoHn .mev unocoo a Am.H xv conumz m>uso cmflac In» E m H» mxma mx mamscc¢ mumcu .unsm .m H N H HI mxmq Hmuoa A tum IE my muflm Edaflxmz H N .muommcmuu m mcu mo mmuam ESEmeE mo some on» Hmsqw mmusmflm muflm ESEmez .ucmHmB who mouwncmm mm mxmq mocmanq mo mmumnmouome oaumsqm on» now mmumn cofluospoumll.m mqmfie 41 themselves during the year. Consequently, the mean annual biomass of each species at each depth of each transect was multiplied by a turnover factor of 3. When a constant winter biomass was not apparent for a particular species and sample depth, a factor of 2 was applied to the mean annual biomass to account for the missing turnover period. Although the calculation was expected to seriously under- estimate productivity as a consequence of using mean annual instead of maximum biomass, the results are quite close to the l cohort Allen curve method (Table 3). In all cases the production of annuals was calculated as maximum ob- served biomass times a turnover factor of 1.5. 3. Marl Removal As previously mentioned, only 42% of the present surface area of Lawrence Lake supports submersed macro- phytes. Of the total lake area, 12% has resulted from marl removal. Excavation has been largely confined to the marl bench area and landward (Figure l). The resulting basins are 3-4 m deep and are completely colonized by macrophytes. Thus little of the original macrophyte zone of the lake was disturbed by dredging, and 21% of the present macrophyte zone is artificial. Based on the Bz-dredged transect data and the 189 g m-"'Zyr-l ash-free dry weight estimate of productivity, the dredged areas of the lake support 29,200 kg or 31% of the total productivity. Consequently, a 12% increase in lake 42 area (6% volume) has caused very significant quantitative changes in submersed macrophyte distribution and production. Estimation of biomass composition of disturbed areas on the basis of the B2 dredged transect is not warranted, however the atypical biomass composition and distribution of that transect suggest changes are to be expected. III . THE SEDIMENTS A. Sediment Traps Sediment traps were placed at the 5 m contour of transects Bl’ B2, B3, and at the deepest point (4.5 m) along transect Bz-dredged. The orifices of the traps were at 4 m, one meter above the sediments (3.5 m along transect B2-dredged). The traps consisted of 65 cm lengths of extruded acrylic tubing (4.44 cm inside diam- eter, wall thickness 2-3 mm). Duplicate traps were placed upright, 50 cm apart at each sampling station. The tubes were held in racks which kept the orifices 25 cm away from the marker line to prevent encrusting material sloughed from the line from entering the traps. The tubes were made opaque to discourage algal coloniZation. The traps were collected and reset at approximately 40—day intervals. The material from the traps was filtered (glass fiber), dried at 105°C, combusted at 550°C, and reweighed. Results are given as ash-free dry (organic) weight. An additivity experiment demonstrated no signi— ficant losses during the sampling interval. The annual pattern shows sedimentation maxima in April and October which correspond to ice-melt and the 43 44 last stages of summer stratification, respectively (Figure 8). Total annual organic sedimentation was highest at transect B3 on the lee side of the lake (251 g m_2yr—l), intermediate at transects B1 and B2 dredged (199 and 183 g m'zyr‘l, respectively), and low- est at transect B2 which was isolated from terrestrial input (169 g m-zyr-l). A two-way analysis of variance with replication, fixed model, was performed to test the significance of transect and annual differences. The assumption of variance homogeneity was verified by the nonparametric Corner Test (Steel and Torrie, 1960). Both factors were significantly different at the 99% level. Interaction was significant at the 95% level (Table 4). As discussed in the introduction, the sediment trap results were not used to estimate sedimentation from the planktonic community. The bimodal periodicity corresponding to periods of turnover and the impossibly high (approximately twice phytOplanktonic production) and variable rates of accumulation in the traps strongly support the contention of Davis (1968) that much of the material captured in sediment traps has been resuspended from the sediments. Sediment traps placed in the hypolimnion of Lawrence Lake produced more reasonable annual patterns and sedimentation rates approximating 10% of phytoplankton production (Miller, 1970). 45 Figure 8.--Annual sedimentation rate [9 m-zday l ash-free dry (organic) weight] pattern at 4 m for each transect including the atypical area of transect B2 (Bz-dredged) where trap depth was 3.5 m. 46 Figure 8 p h p _ p dredged 4. Saxon «Lt 9 2 6 0.2 2 m cams mo mmmummo mo mousom A.Hm>ma mam um ucmoHMflcmflm u xx “Hm>ma mmm um ucmoflMHGmwm n xv .HmUoE pmxflm .GOHuMOAHmoH cufl3 wmzlm .AucmHmB wan mmHMIcmmv wumc awn» ucmfiflcmm on» mo moccaum> mo memhamcmll.v mammfi 48 B. Sediment Core Samples Sediment core samples were taken by means of a small piston corer from the material collected for measurement of benthic respiration. The cores were frozen then sawed into four 2 cm segments (horizons) which included 0-2, 2-4, 4-6, and 6-8 cm strata of the surface sediments. The material was dried at 105°C, weighed, combusted at 550°C, saturated with distilled water to rehydrate clay materials, dried at 105°C, and weighed to determine ash—free dry (organic) weight. Transect B3 on the lee side of the lake had the highest percentage organic weight, and Transect B2, pro- tected from terrestrial input, had the lowest (Figure 9). Transect B1 was intermediate except for an extreme maximum at 7 m (transect-depth interaction is significant at the 99% level). A mean transect plotted over depth and season shows a complex relationship (Figure 10). The percentage organic weight was high at 7 m in summer and fall while that at all other depths is high in fall and winter. This indicates an accumulation of organic material at 7 m during summer stratification, and a redistribution of organic matter associated with fall overturn. A 4—way analysis of variance with replication, fixed model, was performed on the sediment core data (% organic weight) which classified transects, depth, horizons, and seasons as factors (Table 5). Transect, depth, and their interaction terms (Figure 9) contributed most of the 49 Figure 9.--Mean annual percentage organic weight in the surface sediments (0-8 cm) over depth for each transect. 50 Figure 9 DEPTH (m) \l (n (.0 I I I \ /~\N 4%; I (a) 09/7 “3.4a: 0 5 10 15 ORGANIC WEIGHT (percent) 51 .mGOHumsuosam Anamoflmficmflm pocv coNHuoc mcflzocm pcm .cummc Hm>o pommcmnu coma m Mo mucmEHcmm mommusm mcu mo ucmflm3 cacmmuo mmmucmoumm mo mcumupmm HmGOmmmmII.oa mnsmflm 52 oeeeeeeoexoaz o_z<0mo o.— m o o.— m o o.— n 0 Q n o W W W. W W m m. T _||l| _||||I|l W m Wan W W m m. M m m M. .34.”. meEDm OZEdm mmkz_>> ea messed (W) HldECI 53 commeem.a omom~.e om coma xxmmmmm.a Naomm.m me Dom 00mmmmo.a ommv>.m ma cod xxmmhvv.m nomvm.m o no xxmamv>.om vmmmh.o> om omd xxmmmam.ma monom.mm ma om xxmmamn.> mommm.mm m om xxommhw.ma mommm.mm m AcOmmmmv o xxmmmmm.m mmono.m om 0mm xxmqmmm.m Hmooo.mm ma um oxommvm.m mvhmo.m m 04 OOmwmmo.~ mmaao.m m AcoNHHomv U xxnawom.mw mnnmo.omm oa m4 xxmeeee.ama «Hoem.mae m Academe m xxammvo.mmv mwhmh.mmva m Abommcmuav a codedeH.H mmemo.e m Adoepmoeadmmv m oauwfiumum mumsvm Eocmmum moccaum> m and: mo mmmummo mo moudom .mmoav.m u mumsqm cmmz "muommmm umcuo Ham cam mGOHumoHHme cmm3umn mcowuomumucfl «0 85m u Hound maficflmfimm .Hmcofi cmxflm .GOHumowammH cufl3 was Iq “Aucmflm3 who mmHMInmm my mumc muoo ucmfiflcmm on» NO mocmflum> mo mammHMG¢II.m mqmds 54 variance and were highly significant. Season and season interactions were also significantly heterogeneous. Hori- zons were not significantly different at the 90% level, although some horizon interaction terms were significant at 99%. These results suggest that the surface sediments of Lawrence Lake differ with respect to location in the lake and change during the year. The quantitative im- portance of these phenomena is suggested by the homogeneity of the horizons which indicates that as much change occurs at 8 cm in the sediments as at the surface of the sedi— 3 ments. Thus, about 4000 m of sediments appear to be involved in the detritus cycle of the lake. C. Permanent Sedimentation Loss of organic carbon to the permanent sediments was calculated from estimates of the amount of organic carbon in the surface sediments, the thickness of the sediments under the lake, and the age of the lake. An estimate of the water content of the sediments of 80% was derived from Wetzel (1970). The sediment core data showed that the average ash-free dry (organic) weight of the sur- face sediments was approximately 10%. Approximately one- half of this was estimated to be carbon, i.e., 5% of the dry weight. The density of CaCO is 2.2 (Hodgman, 1959), 3 and 9.4 m of sediments exist under the deepest point in the lake (R. O. Kapp, personal communication). The age of Lawrence Lake is probably similar to that of Pretty 55 Lake in northern Indiana which has been radiocarbon dated at approximately 14,000 years before present (Wetzel, 1970). 3 6 6 9.4 m x 10 cc x 20% x 2.2 = 4.14 x 10 g 2 CaCO3/m /l4,000 yrs. 5% organic carbon = 0.207 x 106 9 organic C/m2/14,000 yrs. 0 207 $110 = 14.8 g organic C/mz/year. IV. BENTHIC RESPIRATION A. Introduction Benthic respiration has been traditionally measured by 02 uptake Pamatmat, 1965, 1968; Pamatmat and Banse, 1969; Pamatmat and Fenton, 1968; Carey, 1967; Edwards and Rolley, 1965; Hargrave, l969a,b; Hayes and MacAulay, 1959; Kanwisher, 1962; Odum, 1957a,b; Odum and Hoskin, 1958; Wieser and Kanwisher, 1961). Several workers (Cope- land and Jones, 1965; Park, Hood, and Odum, 1958; Verduin, 1960) using both the COZ-pH change technique which assays CO2 as a function of pH (Beyers and Odum, 1959; Beyers, Larimer, Odum, Parker, and Armstrong, 1963) and the 02 uptake technique in plankton production studies have observed respiratory quotients (RQ = COZ/Oz) greater than one. Preliminary measurements of CO release and 02 up- 2 take by the sediments of Lawrence Lake produced respiratory quotients of 1—3. Consequently, the CO -pH change method 2 was used exclusively in this study to estimate the loss of respiratory carbon from the benthic community. Carbon dioxide was assumed to be the only carbonaceous respira- tory product of the benthic community and the only factor 56 57 influencing the pH changes observed at the sediment—water interface. B. Methods Shallow sediment cores were obtained with a free—fall sampler designed by Dr. G. H. Lauff (unpublished). The sampler consisted of a steel tube threaded to a one-way water valve above and a cutting head below. A clear acrylic tube was held within the steel tube by shoulders below the one-way valve and within the cutting head, and could be removed, containing an intact sample, from either end of the sampler. Upon retrieval of a sediment core, an initial sample was removed from the water overlying the sediments for pH determination and titration. The level of the sediments within the insert was adjusted so that a known volume of water (usually 200 ml) was held between the surface of the sediments and the top of the acrylic insert. The tube was then sealed with either clear acrylic caps or Saran Wrap (Dow Chemical Co., Midland, Michigan), placed in a rack to hold the sediments in place inside the inserts, and returned to the original depth of the sample for incubation. The initial water sample was returned to the laboratory and allowed to reach room temperature (1-2 hours) before electrometric determination of pH was made (Beckman Expandomatic pH meter, Corning combination electrode). 58 After incubation, a second sample was removed from the water trapped over the sediments for pH determination and calculation of the pH change during the incubation period. A smaller core of sediments was taken from the material in the insert by means of a small piston sampler for organic weight analysis (see Chapter III), and the insert was washed in preparation for the next sample. In the laboratory, the initial water sample (100 ml) was titrated with COz—saturated distilled water prepared in a tonometer (Beyers, at 31., 1963), and the pH change observed in the incubated sample was converted to CO2 accumulation (see Appendix I). Four replicates were taken at each depth (1, 3, 5, 7, 9, and 11 m), two as light "bottles" and two having black cloth hoods as black "bottles." The acrylic (cast) in- serts had an inside diameter of 4.49 cm, a wall thickness of 2-3 mm, and light transmission of 92% (Cadillac Plastics & Chemical Co.). Four complete sets of samples were taken along each transect, corresponding to summer (stratified), fall (overturn), winter (stratified), and spring (overturn and early stratification), over the study period. Shortly after starting the sampling regime reported here, the means of sealing the acrylic inserts was changed from hand-lapped acrylic caps to Saran Wrap held with rubber bands. Despite great care in the construction and fitting of the acrylic caps, erratically low results 59 suggested that CO2 was escaping from the incubated samples. Consequently the caps were tested against Saran Wrap and were found to be less dependable. Further, good results using capped inserts were not significantly different from unselected results obtained with Saran Wrap. Observations for a particular date and depth con- sisted of a complete 24—hour diurnal cycle. Depending upon the rate of CO evolution expected, one to four 2 separate samples were incubated for four to 24 hours and summed to obtain a 24-hour duration. A saturation effect was detected (Figure 10) which caused the rate of CO2 evolution to decrease above a certain level of accumulation. An exact determination of the critical accumulation was complicated by normal diurnal changes during the experi- ment. No samples (200 ml) were used for preparation of the annual CO budget which had accumulated more than 2 25 uM C02. The possible effects of bacterial overgrowth stimu- lated by container surface (Zobell, 1943; Zobell and Anderson, 1936) upon respiration were tested in several additivity experiments performed both day and night and using both light and dark bottles. Except during the first one-half hour, storage effects were consistently inhibitory, though not significantly so until accumulation l exceeded 30 uM C02 200 ml- . 60 Figure ll.--C02 accumulation gs. time for three incubation volumes. Variations in 200 ml volume inter- preted as diurnal effects up to approximately 30 uM C02. Vertical lines represent range of two samples. Figure 11 61 I I I I I A 30 F- N ’4 C) umucH mocmcflwcoo woo ucmmmnmmu m>udo GOHDMHUHH co mosaa Havauum> .mcHEHmz can coflumuuommcmuu mcflusc HMHHU OHQEMm mm cam Hound coflpmnuHBII.~H gunmen 64 £58. odes 285.0 2.0 0.0 o _ Ioomeobm min dorm Id< _ _ Hsummer _o:coo Ir H HEeolotoEo _ onN 00. ON. 095 NH deemed 65 .cummc um>o powmcmuu some m mm coflpmuflmmmu vacucmn mo mcumuumm HMGOmmmmII.mH musmflm 2-33-5 025 zo_em~mam m AcOmmmmv o OOmHmmm.H mwmao.aamm 0H 0mm xxmvmmm.m momma.m>moa m um 00mmama.o vvmho.avm m Dd oooeoem.o mmmee.aema H Ammeeuom xemouuemeqv o xxnnmmo.m anmmm.mhmma OH mm xxaommm.me meemm.emeam m Academe m xxaoHHH.n moomv.nvoma m Auommcmnav d oxmmoem.e memem.eeme H Aeoeumoeadmmv m oaumflumum mumsvm Eocmmnm moccanm> m add: no mmmummo mo condom A.Hm>da wmm um unmoflmwcmfim u xx “Hm>ma wmm um unmoflmwcmflm n xv .Hmvam.vmma n mumsvm cum: ”muommmm Hmcuo Ham cam mcofiumoflammu cmmSuwn mGOHuomumuCH mo 55m n Hound mcflcflmEmm .Hmcofi pmxwm .GOHumoflammn cufl3 >m3Im «dump coflumuflmmmu oanucmn may no mocMHHm> mo mflmwamcfiII.m mqmda 69 oonoom.o mommv.HOHH om maom< xxHhmvm.m ovmom.mmmm mH moum OOmMHmm.o memv.MHmH m moufi OOmNmmN.o mHmHo.mmm m mou xmeomH.¢ mbHam.ohmw om momd xanmm>.Hm aanmom.HHmmm mH mom xmemmH.om bonmmm.>mmmm w mad xxmomov.MHm mo>m~.ovom>m m mo OOnHmmH.H whomm.HmHm OH mum< 00m>va.H mmHmm.mva m mum OONmmmh.o mnan.HmmH m mum OOmmNho.m mmomm.mmmm H MD 00m¢m-.H mmmmm.mmm~ 0H mm< xvamHm.m~ HmnHw.HmHma m mm xmemhm.m mHmHm.mman m Nd xxnmmm~.mHm mmmmm.>Hm¢nm H AcoHnmm HmcusHoV m UHumHumum mumsqm Eocmmum mUGMHum> m and: mo mmmnmmo mo condom AcdeHucoovII.m mqmds V. CONCLUSIONS An Annual Benthic Carbon Budget for Lawrence Lake Inputs: 1 -2 -l Submersed macrophytes: +87.9 g C m yr Epiphytes:2 +39.9 Sedimentation:3 +10.2 Terrestrial:4 + 5.2 Outputs: Benthic respiration: -1l7.5 Permanent sedimentation: - 14.8 -2 -1 Balance: + 8.9 g C m yr 1. Calculated from ash-free dry (organic) weight by a factor of 46.5% (Westlake, 1965). 2. From Allen (1969). 3. Calculated as 20% phytoplankton production (Miller, 1970). 4. Estimated as 200 g C m-1 shoreline (Szczepanski, 1965). 70 LITERATURE CITED LITERATURE CITED Allen, H. L. 1969. Primary productivity, chemo- organotrOphy, and nutritional interactions of epiphytic algae and bacteria on macrOphytes in the littoral of a lake. Ph.D. Thesis. Michigan State Univ. 186 + xv. Allen, K. R. 1951. The Horokiwi Stream: A study of a trout population. Fish. Bull. Wellington, N.Z. Beyers, R. J. and H. T. Odum. 1959. The use of carbon dioxide to construct pH curves for the measurement of productivity. Limnol. Oceanogr. 4:499-502. Beyers, R. J., J. Larimer, H. T. Odum, R. B. Parker, and N. E. Armstrong. 1963. Directions for the determi— nation of changes in carbon dioxide concentration from changes in pH. Publ. Inst. Mar. Sci. Univ. Texas 9:454-489. Borutskii, E. V. 1950. (Data on the dynamics 0f the biomass of the macroPhytes of lakes.) In Russian Trudy vses. gidrobiol. Obshch. 2:43-68. Brock, T. D. 1966. Principles of microbial ecology. Prentice-Hall, N.J. 306 + xiv. Burkholder, P. R. 1956. Studies on the nutritive value of S artina grass growing in the marsh areas of coastaI Georgia. Bull. Torrey Bot. Club 83:327-334. and L. M. Burkholder. 1956. Vitamin B12 in suspended solids and marsh muds collected along the coast of Georgia. Limnol. Oceanogr. 1:202-208. and G. H. Bornside. 1957. Decomposition of marsh grass by aerobic marine bacteria. Bull. Torrey Bot. Club 84:366-383. 71 72 Carey, A. G., Jr. 1967. Energetics of the benthos of Long Island Sound. I. Oxygen utilization of sedi— ment. Bull. Bingham Oceanog. Collection 19:136-144. Copeland, B. J. and R. S. Jones. 1965. Community metabolism in some hypersaline waters. Texas Jour. Sci. 17:188-205. Cummins, K. W., W. P. Coffman, and P. A. Roff. 1966. Trophic relationships in a small woodland stream. Verh. Internat. Verein. Limnol. 16:627-638. Darnell, R. M. 1964. Organic detritus in relation to secondary production in aquatic communities. Verh. Internat. Verein. Limnol. 15:462-470. Davis, M. B. 1968. Pollen grains in lake sediments: redeposition caused by seasonal water circulation. Science 162:796-799. Deeter, E. B. and F. W. Trull. 1928. Soil survey of Barry County, Michigan. U.S. Dept. Agr. Bur. Chem. Soils, Ser. 1924, No. 14. 20 pp. Edwards, R. W. and H. L. J. Rolley. 1965. Oxygen con- sumption of river mud. J. Ecol. 53:1-19. Fassett, N. C. 1960. A manual of aquatic plants. Univ. Wisc. Press, Madison. 405 + ix. Felfoldy, L. and F. K. Zsuzsa. 1958. Cellulozebontas mértéke a Balaton Kfildnbdzd biotdpjaiban és annak mérése antron reagenssel. Annal. Biol. Tihany 25:209-215. Fernald, M. L. 1950. Gray's manual of botany. 8th ed. American Book Co. 1632 + lxiv. Fox, D. L. 1950. Comparative metabolism of organic detritus by inshore animals. Ecology 31:100-108. Fredeen, F. J. H. 1960. Bacteria as a source of food for black-fly larvae. Nature London 187:963. . 1964. Bacteria as food for blackfly larvae (Liptera:Simu1iidae) in laboratory cultures and in natural streams. Canad. J. Zool. 42:527-548. Goldman, C. R. 1961. The contribution of alder trees (Alnus tenuifolia) to the primary productivity of Castle Lake, California. Ecology 42:282-288. 73 Hargrave, B. T. l969a. Epibenthic algal production and community respiration in the sediments of Marion Lake. J. Fish. Res. Bd. Canada 26:2003-2026. . 1969b. Similarity of oxygen uptake by benthic communities. Limnol. Oceanogr. 14:801—805. Hayes, R. F. and M. A. MacAulay. 1959. Lake water and sediment. V. Oxygen consumed in water over sedi- ment cores. Limnol. Oceanogr. 4:291-298. Hodgman, C. D. (ed.) 1959. Handbook of chemistry and physics (4lst Ed.). Chemical Rubber Publishing Co., Cleveland. 3472 + xxiv. Hutchinson, G. E. 1964. The lacustrine microcosm revisited. Am. Sci. 52:334-341. Hynes, H. B. N. 1963. Imported organic matter and secondary productivity in streams. Proc. 16th Int. Congr. Ent. Washington 4:324-329. Kanwisher, J. W. 1962. Gas exchange of shallow marine sediments. Proc. Symp.: The environmental chemistry of marine sediments. Occas. Publ. (Grad Sch. Ocean- ogr., Univ. of Rhode Island) 1:13—19. Kaushik, N. K. and H. B. N. Hynes. 1968. Experimental study on the role of autumn-shed leaves in aquatic environments. J. Ecol. 56:229-243. Kormondy, E. J. 1968. Weight loss of cellulose and aquatic macrophytes in a Carolina bay. Limnol. Oceanogr. 13:522-526. Leverett, F. and B. B. Taylor. 1915. The pleistocene of Indiana and Michigan and the history of the Great Lakes. U.S. Geol. Surv. Monogr. 53. U.S. Gov't. Printing Office, Washington, D.C. 523 pp. Mathews, C. P. and D. F. Westlake. 1969. Estimation of production by populations of higher plants subject to high mortality. Oikos 20:156—160. Miller, M. C. 1970. Primary production and extracellular release by phyt0p1ankton and its role in carbon cycling in lakes. Ph.D. Thesis. Michigan State Univ. Minshall, G. W. 1967. Role of allochthonous detritus in the trophic structure of a woodland springbrook com- munity. Ecology 48:139—149. 74 Nauwerck, A. 1963. Die Beziehungen zwischen ZOOplankton und Phytoplankton in See Erken. Symb. Bot. Upsal. 17:1-163. Nelson, D. J. and D. C. Scott. 1962. Role of detritus in Odum, Odum, the productivity of a rock-outcrOp community in a Piedmont stream. Limnol. Oceanogr. 7:396-413. E. P. and A. A. de la Cruz. 1963. Detritus as a major component of ecosystems. AIBS Bull. 13:39-40. and . 1967. Particulate organic detritus in a Georgia salt marsh-estuarine ecosystem. In Estuaries (Ed. G. H. Lauft), AAAS, 383-388. H. T. 1957a. TrOphic structure and productivity of Silver Springs, Florida. Ecol. Monogr. 27:55-112. . 1957b. Primary production measurements in eleven Florida springs and a marine turtle-grass community. Limnol. Oceanogr. 2:85-97. and C. M. Hoskin. 1958. Comparative studies of the metabolism of marine waters. Publ. Inst. Mar. Sci. Univ. Texas 5:16-46. Pamatmat, M. M. 1965. A continuous-flow apparatus for Park, measuring metabolism of benthic communities. Limnol. Oceanogr. 10:486—489. . 1968. Ecology and metabolism of a benthic com- munity on an intertidal sandflat. Int. Revue ges. Hydrobiol. 53:211-298. and K. Banse. 1969. Oxygen consumption by the seabed. II. £3 situ measurements to a depth of 180 m. Limnol. and Oceanogr. 14:250-259. and D. Fenton. 1968. An instrument for measuring subtidal benthic metabolism in situ. Limnol. Oceanogr. 13:537-540. K., D. W. Hood, and H. T. Odum. 1958. Diurnal pH variation in Texas bays and its application to pri- mary production estimation. Publ. Inst. Mar. Sci. Univ. Texas 5:47-64. Ragotzkie, R. A. 1959. Plankton productivity in estuarine waters of Georgia. Inst. Mar. Sci. Univ. Texas 6:146-158. 75 Ragotzkie, R. A. and R. A. Bryson. 1955. Hydrography of the Duplin River, Sapelo Island, Georgia. Bull. Mar. Sci. Gulf Carib. 5:297-314. Rich, P. H. 1966. Productivity of aquatic macrophytes at Erie Marsh. MS Thesis. Michigan State Univ. 103 + vii. . 1970. Post-settlement influences upon a south- ern Michigan marl lake. Mich. Bot. 9:3-9. and R. G. Wetzel. 1969. A simple, sensitive underwater photometer. Limnol. Oceanogr. 14:611-613. , R. G. Wetzel, and N. V. Thuy. (in prep) Distri- Eution, production and role of aquatic macrophytes in a southern Michigan marl lake. Rodina, A. G. 1963. Microbiology of detritus of lakes. Limnol. Oceanogr. 8:388-393. Ross, H. H. 1963. Stream communities and terrestrial biomes. Arch. Hydrobiol. 59:235-242. Smalley, A. E. 1960. Energy flow of a salt marsh grass- hOpper population. Ecology 41:672-677. Smith, F. A. 1967. Rates of photosynthesis in Characean cells. J. Exp. Bot. 18:509-517. Starr, T. J. 1956. Relative amounts of vitamin B12 in detritus from oceanic and estuarine environments fig“ near Sapelo Island, Georgia. Ecology 37:658-664. Fm , M. E. Jones, and D. Martinez. 1957. The pro- I duction of vitamin Blz-active substances by marine ; bacteria. Limnol. Oceanogr. 2:114-119. ” Steel, R. G. D. and J. H. Torrie. 1960. Principles and procedures of statistics. McGraw-Hill Book Co., 3 Inc., N. Y. 481 + xvi. .1_y Szczepanski, A. 1965. Deciduous leaves as a source of organic matter in lakes. Bull. L'Acad. Pol. Sci. II, 13:215-217. Teal, J. M. 1957. Community metabolism in a temperate cold spring. Ecol. Monogr. 27:283-302. Veatch, J. O. 1953. Soils and land of Michigan. Michigan State Coll. Press, E. Lansing. 241 + xi. 76 Verduin, J. 1960. Phytoplankton communities of western Lake Erie and the C02 and 02 changes associated with them. Limnol. Oceanogr. 5:372-380. Westlake, D. F. 1965. Theoretical aspects of the com- parability of productivity data. Mem. lst Ital. Idrobiol., 18 Supple.:313-322. . 1966. A model for quantitative studies of photosynthesis by higher plants in streams. Air wato POllUt. Int. J. 10:883-896. Wetzel, R. G. 1969. Factors influencing photosynthesis and excretion of dissolved organic matter by aquatic macrophytes in hard-water lakes. Verh. Internat. Verein. Limnol. 17:72-85. . 1970. Recent and post-glacial production rates of a marl lake. Limnol. Oceanogr. 15. and D. L. McGregor. 1968. Axenic culture and nutritional studies of aquatic macrophytes. Am. Midl. Nat. 80:52-64. , H. L. Allen, P. H. Rich, and M. C. Miller. (in prep) Dynamics of autotrophic productivity of a marl lake. Wieser, W. and J. Kanwisher. 1961. Ecological and physiological studies on marine nematods from a small salt marsh near Woods Hole, Massachusetts. Limnol. Oceanogr. 6:262-270. Wood, R. D. and K. Imahori. 1964. A revision of the Characeae. Vol. II. Iconograph of the Characeae. Cramer, Weinheim. 6 + 395 plates. and . 1965. A revision of the Characeae. Vol. I. Cramer, Weinheim. 904 pp. Zobell, C. E. 1943. The effect of solid surfaces on bacterial activity. J. Bact. 45:39-56. and D. Q. Anderson. 1936. Observations on the multiplication of bacteria in different volumes of stored sea water and the influence of oxygen tension and solid surfaces. Biol. Bull. 71:324-342. 1..”l1‘h1a-AII1K-wis 9......) ~ 1 APPENDIX "’l APPENDIX I RESPIRATION CALCULATIONS M = mM CO2 ml-1 titrant (obtained from Table 3, Beyers, 33 31., 1963). M' = M corrected for volume of titrant used = volumetit x M. I M' = X . APHincub. x M = X APEiton. APHincub. APHton. Correction for 200 ml incubation = 2 x X100ml (titration) = Xsample 2 X/m Xsample x 631.56 2 X/m2 'incub. Errors: 1. Dilution effect upon pH of titration: Error for 0.5 ml distilled H 0 when pH. 2 initial is above 7.00 = 0.005 x 7.00 - pHinitial = 0.005 x -l.00 = -0.005 at pH 8.00. Net effect: increases ApH tonometer and decreases AC02 sample estimate. 77 78 2. Volume change of titration: Factor for volume. - 100.5 :1 = 0.025 for incub. - . 0.5 m1 titrant. Net effect: increases AC02 estimate. Net effect: errors tend to cancel, resulting in a small under-estimate of ACOZ. r”? l&.l'.'.a ...~"' 2', . III.\-‘.I" 'llllllII " Ill! I’ll l (Jill (Ill; q.v.lrivd “INHIHCH .4..;|II|.UM.., .lf'fllflul .In/A. xi“ “IIIIIIIIIIIIIII“