A COMPARATIVE STUDY OF STANOTNO CROPS ANO __ 0F PHOSPHORUS ANO NITROGEN. CONTENTS OE ' FOUR MACROPHYTE STREAM COMMUNITIES ' Thesis for the Degree of MS. MICHIGAN STATE UNIVERSTT‘Y THOMAS J. POPMA 1971 ABSTRACT A COMPARATIVE STUDY OF STANDING CROPS AND OF PHOSPHORUS AND NITROGEN CONTENTS OF FOUR MACROPHYTE STREAM COMMUNITIES BY Thomas J. Popma Four 100 meter study sections were chosen in three Michigan streams to evaluate the influence of varying levels of eutrophication upon submerged macrophyte com— munities. Choice of study sites was based upon appearance of the streams and prior estimates of physical, chemical, and biological parameters. Phosphorus content within plant tissue reflected concentrations in the water. The percentage of phosphorus in tissue was high in spring, but could not be shown to change significantly during the latter part of the growing season. Nitrogen content in tissues appeared to remain at levels required to maintain constant N:P ratios rather than reflect water concentrations. The size of standing crop seemed to be influenced more by stream morphology within the study site than by levels of enrichment. However, percent deviation of organic standing crOp from the May 1 to October 1 average Thomas J. Popma in each stream increased directly with apparent increased eutrophication: August deviations of 8%, 60%, 130%, and 280% were recorded at the sites, listed here in order of increasingly eutrophic status. A COMPARATIVE STUDY OF STANDING CROPS AND OF PHOSPHORUS AND NITROGEN CONTENTS OF FOUR MACROPHYTE STREAM COMMUNITIES BY 91, Thomas prfiopma A THESIS Submitted to Michigan State University in partial fulfillment of the requirements for the degree MASTER OF SCIENCE Department of Fisheries and Wildlife 1971 ACKNOWLEDGMENTS I am grateful to Dr. Clarence D. McNabb for the direction and encouragement he has given me in this study, to Drs. Niles R. Kevern and Brian Moss for their review of the manuscript, and to the many people who have helped in collecting and processing data. Water samples were collected by Adam Szluha. Chemical analysis of the water and determination of the nitrogen content in plant tissue were performed by person- nel in the Institute of water Research Water Quality Laboratory, Michigan State University. The work upon which this thesis is based was supported by funds from Grant 14-31-0001-3153, provided by the United States Department of the Interior, Office of Water Resources Research, as authorized under the Water Resources Research Act of 1964. Financial assistance and equipment were also provided by the Agricultural Experiment Station, Michigan State University. ii TABLE INTRODUCTION . . . . . DESCRIPTION OF STUDY SITES METHODS. . . . . . . RESULTS. . . . . . . Phosphorus. . . . . Nitrogen . . . . . Standing crop. . . . DISCUSSION. 0 o o _o 0 OF CONTENTS Phosphorus content in plant Nitrogen content in plant tissue . Standing crop. . . . LITERATURE CITED. . . . APPENDIX D O O O 0 O Scale maps of study sites. Statistical formulas . tissue. Phosphorus concentrations of species not common to more than one site Percent ash-free estimates of dried plant material. . . . . Phosphorus standing crop . iii Page ll 14 26 26 28 33 36 36 40 42 43 45 LIST OF TABLES Table Page 1. Physical and chemical water parameters at study sites during growing season (collected 4/12, 5/3, 5/31, 6/26, 8/11, 9/4, 9/25/70) . . . . . . . . . . . 4 2. Percent phosphorus in oven dried plant tissue (x + 90% C.I.) and phosphorus concentratIon (mg/liter) in water at four stream sites . . . . . . . . . . . 9 3. Percent nitrogen in oven dried plant tissue (x + 1 SE,n) and NO3-N/NH3-N concentration (mg/liter) in water at four stream sites. . . . . . . . . . 12 4. Seasonal ratio of nitrogen to phosphorus of species common to more than one site and of water, calculated from the mean values of each collection date. E’i 1 SE (n). . . . 15 5. Correlation coefficients (r) of seasonal changes in dry weight standing crops to density within colonized areas and to percent stream bottom colonized with plants . . . . . . . . . . . . -. 23 A1. Percent phosphorus of oven dried plant tissue for species not common to more than one site. x i 90% C.I. . . . . . . 42 A2. Percent ash free weights of oven dried plant material at four stream sites. x i 1 SE (n) . . . . . . . . . . . 43 A3. Standing crops of phosphorus (mg P/mz) at four stream sites. x :_1 SE . . . . . . 45 iv Figure 1. Al. LIST OF Species composition and crop for total study River. (X + 1 SE) . Species composition and crop for total study River. (x + 1 SE) . Species composition and cr0p for total study River. (x + 1 SE) . Species composition and crop for total study River. (x + 1 SE) . Percentage estimates of FIGURES dry weight standing site in upper Jordan dry weight standing site in lower Jordan dry weight standing site in AuSable dry weight standing site in Red Cedar proportion of stream bottom colonized by submerged macrophyte communities in four study sites. (i'i 1 SD) . Submerged macrOphyte dry weight standing crops for colonized portions of four stream sites. (56:1 SE). . . . . . Percent deviation of standing crOps of organic plant material from May 1 to October 1 average in plant communities of four stream sites. (x + 1 SE) . . . . Percent deviation of standing crOps of organic plant material from May 1 to October 1 average for selected species. (§'+ 1 SE). . . . Scale map showing configuration, location, and sampling zones of upper Jordan River study site. . . . Page 16 17 18 19 20 22 24 31 36 Figure Page A2. Scale map showing configuration, location, and sampling zones of lower Jordan River study site . . . . . . . . . . . 37 A3. Scale map showing configuration, location, and sampling zone of AuSable River study Site 0 O O O O O O O O O O O O 38 A4. Scale map showing configuration, location, and sampling zones of Red Cedar River study site . . . . . . . . . . . 39 vi INTRODUCTION Tissue analyses of aquatic plants have been widely reported in the past (Schuette and Hoffman, 1921; Schuette and Alder, 1927, 1929; Harper and Daniel, 1934; Misra, 1938; Gorham, 1953; Anderson et a1., 1965; Boyd, 1969b). Factors affecting these tissue levels have also been investigated. The extent to which tissue content reflects environmental concentrations has been evaluated in the field by Weatherly (1955) and under laboratory conditions by Gerloff (1966). Likewise, the influence of season upon these levels has been investigated in lakes: in a June- September study Gerloff (1969) reported nitrogen and phosphorus levels in plant tissue, and Caines (1965) monitored plant phosphorus levels before and after ferti- lizing a small lake. Edwards and Owens (1960) and Owens and Edwards (1961, 1962) have reported on productivity studies of aquatic plants in streams, but until recently productivity determinations and tissue analyses have been conducted independently. Forsberg (1960) and Boyd (1969a) investi- gated both of these factors in lakes, and Stake (1967, 1968) studied a small polluted stream well colonized by emergent macrophytes. In this study, streams of differing water quality were chosen in an attempt to evaluate the influence of eutrOphication upon seasonal changes in standing crop and upon the nitrogen and phosphorus content in tissues of submerged macrophyte communities. An underlying objective was to test the feasibility of using these parameters as indicators of degree of eutrophication. DESCRIPTION OF STUDY SITES Three rivers in Michigan with varying nutrient levels were chosen for this study. Four 100 meter long stations, each supporting macrophyte communities considered representative of the stream type in which it was located, were established as follows: (1) the headwaters of the Jordan River, representing pristine water conditions; (2) the still unpolluted lower reaches of the Jordan River, flowing through an area of few farms and few cabins; (3) a site on the AuSable River, located in the recovery zone (Brege, 1969) of a sewage treatment plant for a community of 2,000, nine river km upstream; and (4) a site on the Red Cedar River, representing poor water quality conditions. In contrast to the three other sites, the Red Cedar is located in southern Michigan where population densities are high and soils have a relatively greater clay content. The water is colored, often turbid, and oxygen levels below 1 mg/liter are common in the summer months. Perti- nent water parameters for these sites are given in Table 1. Location and configuration of study sites are presented in the Appendix, Figures Al-A4. AvH.HTmH.V Aam.muom.v Amvmuomvv Ammmummmv oo.a m.H|o.H manma umomu pom mv.o mH.H Hmm «mm Amo.lmo.v Amm.umo.v Ammmlmmav Ammaummav mH.c o.alm.o mmlom wanmmsm mo.o oa.o nma mva Amo.lao.v Avm.umm.v Aommnmmav Aaomlanav mo.o o.HTm.o malma cmpHOh umBOH v0.0 mm.o cam mmH Amo.THo.V Aem.|mm.v Aoamunmav Ammauvmav Ho.o m.onv.o walma GMUHOh uwmms no.0 N>.o mma mma msuonmmonm szoz m©HH0m mmmcpumn .uosam .wmum .qwum Hmuou Hmc0mwmm umoE umoE appHB um>flm shame memmwfi 33:85 33.55 9: H3338 .Aon\m~\m .v\m .Ha\m .mm\w .Hm\m .m\m .ma\v Umuomaaoov 20mmmm OCHBOHm mafiuso mmuflm wpsum um mumumEmumm Hmumz HMUHEmno paw HMUHmwnm .H mumme METHODS The boundary of a plant bed is often indistinct, and an estimation of bed size can be a decidedly subjective decision. Methods were used to give an unbiased estimate of the percent stream bottom occupied by a given species and also to minimize the number of sampling points re- quired for a reliable estimate of standing crop. Each study site was mapped using a plane-table, and total surface area was estimated with a compensating polar planimeter. Since, except for the AuSable, vege- tation existed only along the shoreline, a boundary of the area to be sampled at each site was permanently established, and was defined as that line outside of which little plant growth would be likely to occur at any time during the growing season. The proportion of the site included in the sampling zone was then determined, and this constant was used to convert standing crop and cover estimates from a sampling zone basis to a total site basis. Percent cover within the sampling zone was estimated from the quotient of samples containing a given species and the total number of samples taken. Standing crop within colonized areas of the stream was estimated from only those samples containing a given species. Heterogeneity of plant growth made a large number of samples desirable, yet minimum disturbance was needed to reduce bias for subsequent estimates. The number of sampling points, randomly located by means of a grid, was set at about 100, and a circular sample area of 0.02m2 was used. Since plant distribution was more homogeneous at the AuSable site, the area per sample was increased to 0.09m2, and the number of samples reduced to 30-36. This aquatic macrophyte study was confined to submerged species. Therefore, the few scattered emergent species present (Typha sp., Iris sp., Nasturtium sp., sedges) were not collected at any site. Material collected was hand washed in tap water, oven dried at 80C for 3-5 days, and weighed to the nearest 0.01 g. Subsamples of each plant species were ground in a Wiley Mill until they were fine enough to pass through a #20 screen (no. mesh per inch). Weighed aliquots of each species were ashed at 550C for 75 minutes for estimates of dry organic weight. Total phosphorus determinations were made spectro- photometrically by a modification of the vanadomolybdate method of Rickey and Avens (1955). A mixture of nitric and perchloric acids (3:1), to which 2.0 g/liter sodium bromide had been added, was used for digestion of the plant material. According to Lueck and Boltz (1956) sodium bromide reduces interferences from germanium, arsenic, and silicon. For nitrogen analysis, additional grinding through a #40 screen was required. Aliquots were then analyzed in a Perkin-Elmer Elemental Analyzer. This instrument automatically measures the thermal conductivity of combustion products (C02, H20, nitrogen) and expresses the elements as percentages of dry weight. RESULTS Phosphorus Per cent phosphorus in dried plant material for all species increased in May, decreased sharply in June, and could not be shown to change significantly during the remainder of the growing season. Differences in phosphorus content in plant tissue reflected the site differences in phosphorus enrichment of the water. Tissue levels for all species common to at least two sites, along with concen- trations of phosphorus in the water, are given in Table 2. Phosphorus content of species not common to more than one site are listed in Appendix, Table A1. Estimates of concentrations in the water probably were not representa- tive of averages for time periods at which plants were sampled since each estimate was obtained from a single water sample. However, judging from the average seasonal values of phosphorus concentrations in the streams (Table 1), levels rose progressively from the upper Jordan to the lower Jordan to the AuSable to the Red Cedar. Phosphorus content of the plant tissues from these sites generally increased in the same order. The estimates coflemu T Ho. Hem. mm. “mm. memcmemceo .m Tmom> vo. Hmm. v Tvm. mammwuo .m oz eo. +mm. v mo. +em. mm. mesuomeefle .m mm. no. mo. mo. mmeaz Hm\m eoflumu Tam. v eo. “em. mo. Hem. memcmeeceo .m Tmmm> No. +mm. Tee. T msQMAuo .m oz em. v oo. +om. oo. +em. magnoeflaflm .m mH.o eo. mo. Ho. mmamz m\m me. Mme. v oo. wem. mamememeeo .m emHm2mm ma. Hem. v mm. ”mm. mammauo .m eoz mo. Tee. v No. Tao. meereAHee .e H\N TTT mo. mo. TTT mmaaz oe\e\m ha. Mmm. v 00. Mam. mm. mflmcmcmcmo moccam eOHQEem no. Hee. v mm. ”mm. T msmmeuo .e uoz eo. +em. v mo. +ea. mo. +HH. maEAOeeHee eoummosmuom me\em\a umvmo pom manmmsm CMUHOU cmcuoo umum3\mwwommm dump umzoa momma um>wm .mouwm Emmnum “now no umum3 cw Ammufla\mfiv coaumuucmocoo msuonmmosm paw A.H.U wom + my mammfiu ucme omflnp cm>o :H monogamonm usmoumm .N mam¢9 10 em. Hem.e om. HHe.H ma. me. Hee. mm. em. Hoe. ee. Hee. em. he. coHHmu Immw> oz hm. mo. mm. mo. ma. ma. vo. mo. «0. oo. mm. No. Hem. Hem. +ee. mo. Hem. Hee. +me. eo. Tee. +ee. Hee. eo. Hoe. Hem. +me. ee. VVV VAV AV VAV mo. mo. mm. mo. mo. mo. Hm. mo. mo. mm. mo. 0H. mm. Ho. Hem. v Wee. v Hoe. +mH. v He. Hem. Ham. Hum. +mH. v mo. AV Mom. +Hm. Hee. A He. Mam. A Hmv. +mH. A we. mo. HeH. eo. Hme. eo. HeH. Ho. eo. Hee. ee. eo. HeH. mo. ee. Hme. eo. me. Hem. ma. vo. mHHmmHs> . Haamuunc . mHmeUmcmo . mummHHo .m mHEHOMHHHm .m mm8<3 MEI-1:11 MHHmmHD> MHHsmmHm mHmcmcmcmo .m mammHHo .m mHEHOMHHHm .m mmedz Heeeuusc .m mHmcmpcmo .m mammHHo .m msumcHuomm .m mHEHOHHHHm .m mmadg mHmcmcmcmo .m mammHHo .m mHEHomHHHm .m mme¢3 ee\e Ha\m mm\h eexe Hm\e 11 which did not follow this order were usually obtained from a single tissue sample or from highly variable samples. Variance at a given date and site depended upon the species involved: Potamogeton filiformis Pers. and Hippuris vulgaris L., both characterized by fleshy tissues, showed less variability than Potamogeton crispus L. and Elodea canadensis (Michx.) Planchon, whose sup- porting tissues more noticeably alter with physiological age. Nitrogen Percent total nitrogen in dried plant material was initially high in May, but decreased continually during the growing season at all sites. These estimates, along with nitrate and ammonia concentrations in the water, are given in Table 3 for all species common to more than one study site. Nitrogen levels in the tissues of P. filiformis were consistently highest in the AuSable, intermediate in the lower Jordan, and lowest in the upper Jordan. There were indications that contents of P. crispus followed this same trend. However, nitrate and ammonia concentrations of the water showed a reverse trend. The ratio of nitrogen to phosphorus in the plant tissue could not be shown to change during the growing season at any of the sites. Although the ratio of nitro- gen to phosphorus in the water varied widely between 12 eoeome Amveo. wee.e Azmvmo. Hme.m Alec eH.m memoooeceo .m Toeo> zmveo. Hee.m Alec Tee.m esemeeo .m oz levee. +eo.e vzmveo. +ee.e VAHV ee.e mHEHoHHHHe .o He.H\ee.o eo.o\ee.o oe.o\mm.e He.H\ee.o emaez em\m coeweo levee. Wem.m vlevme. Hoe.e Azevme. Hme.m memeooeeeo .m To o> levee. +ee.m VAHV Tee.e moomeuo .e oz lee em.m vzevem. +oe.e meseoeeaee .e me.o\ee.H ee.o\eo.o me.o\ee.e ee.o\ee.o emaez m\m levee. meH.e Almvme. wee.e vlev em.e memooeeeeo .m ooHoEee Amvee. Hee.e vzeveo. Hee.H memeeuo .e uoz zmceo. +me.e vzmvmo. +He.e meseoeeeee .e eH.o\Hm.o oe.o\mm.o emaez oe\e\e lmvem. Hee.e T T Heeeeoso .m levee. Hee.e v me. HeH.e VAHV ee.e memooeeeeo eoooem 1H1 He.e elecee. Hme.m vlmvee. +ee.e T esomeuo .e Amvmo. +ee.e szmH. +em.H mHEHoHHHHH cooomoEeuom ee\ee\e HMUOU Umm waflmmsd CMUHOb GMOHOb Hmum3\mwwommm Guano HmBOH Homes Hm>Hm .mmuHm mmmuum Hsow um kum3 CH AumuHH\mEv coHumuucmocoo Zimm2\zlmoz Ucm AG.Mm H +_Mv mammHH pcwam @mHHU cm>o CH comouuH: usmoumm .m mummy l3 levee. Hee.e levee. Wee.e zeeme. Hee.e vzecee. Hme.m HN.o\HN.N memEmm Hoz ee.H\ee.o coHumu Tomm> OZ Hm.o\mm.H coHumu Immo> oz mm.o\mm.o Amvma. +oo.m mm.o\oa.o levee. wee.m levee. +me.e Ho.o\ho.o lee Teo.e zeeem. Hee.m Amvmo. +me.m eo.o\eo.o lee Tee.m levee. Hee.e AmVHH. +mh.~ eo.o\ee.o VAV VV VVV VAV i levem. Hee.e vzecee. HmH.e levem. +ee.e AHV Tem.m levee. +ee.H eH.e\ee.o zevme. Hee.e lmvee. Hee.e levee. Hme.e zmceo. +ee.H Alevee. Hme.e vleeeo. Hme.H ee.o\ee.o vzeeme. Hee.e AAHV mm.m vzevme. Hoe.e eo.o\em.o eo.o\em.o Amvme. Hme.e levee. Hee.e Amome. +me.e eo.o\em.o He.o\ee.o lee Tee.m vlec Tee.e Amvme. Hee.e.AAevoe. +ee.e levee. Hme.m Aevme. +Hm.e VAHV me.e mo.e\mm.o ee.o\me.o MHHmmH9> HHHeuesc mHmcoomcmo mammHHo mHEHOHHHHm mmdmé mmefig mHHmmHs> mHmchmcmo mDQmHHo mHEHOHHHHm .m .m .m .m mmeflz mHmcmomcmo mommHHo mHEHOMHHHm .m .m .m mm943 MHmcoomcmo mammHHo mHEHOHHHHm mHHmmHs> mHHsmmHm .m .m .m mmafig eexe He\e mH\h em\m 14 sites, this ratio remained constant in the tissues of a given species (see Table 4). Standing crOp Species composition and standing crop estimates, calculated on an entire site basis, are presented in Figures 1-4. These estimates are functions of two factors: percent stream bottom colonized by aquatic plants and density within these colonized areas. At any given date standing crop differences between sites were attributed primarily to differences in the percentage of stream bottom colonized by plants. These differences in amount of cover, presented in Figure 5, appeared to be not as closely related to levels of enrichment as to other factors, such as stream configuration, flow rates, and turbidity. Specifically, the upper Jordan (pristine, but shallow, with areas of slow flowing water) supported a greater biomass than the lower reaches of the Jordan (deeper, with a fast flowing straight channel); the AuSable (third most eutrophic site) did support the greatest biomass, but the Red Cedar (extremely eutrophic and turbid) contained the least. Since the establishment and growth of a plant community are influenced by factors other than nutrient availability, standing crop estimates based only upon colonized portions of the stream could tend to mask these other influences and better reflect enrichment levels. 15 AHV mH lee H H e lee e H ee lee HH H em Hope: Ame o H HH lee H H eH eHeeeHo> eHooeon rev H H e lee H H HH Hes H H OH mHeoooeeeo eooon 1H1 e rev H H e lee H H e mooeHeo .e lee H H OH Hey e H eH lee H H mH eHaHoHHHHe ooeoeoaeooe Hopmu pom OHQmmsd cmonoo cmeOb kum3\mmHommm Hmzoa Home: Emmuum loo mm H H x .oeeo COHHOOHHOU zoom Ho mosam> some mnu EOHH woumHsoamo .Houm3 Ho paw mHHm oco cosy mHOE 0H GOEEOU mmHooam Ho msuocmmonm ou cmmOHHHc mo OHHMH Hmcommmm .e mamas 16 Hmm H +5 .Hm>Hm cmouoo Comm: CH muHm wcsum Hmuou HOH mono mCchmum quHOS who UCm COHuHmomEOU meummm .H mHCmHm WT Tu 1. T4 4 0 .J I. 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A mH. meHQEoo HHC Hm>oo mnmn Ho>oo moon Hm>oo moon Hw>oo moon mmHommm CHCHH3 CHCHH3 CHCHH3 CHCHH3 muHmCmU wuHmme muHmCmp muHmme Hmpou pom wHQmmCC CMUHOH Hm3oH CMUHOU Hmmms Hw>Hm .mHCMHm CHHB UmNHCoHoo Eovuon Emmuum HCmoumm 0H pCm mmoum noNHCoHoo CHCHHB wuHmCmp OH macho mCHUCmum HCmHo3 >HU CH mmmCmno HMCOmmwm Ho HHH mHCmHoHHHwoo CoHHMHmHHOU .m mqmde 24 Comm HmHHmumE “CMHQ UHCmmHo Ho mmouo mCHUCmum Ho COHHMH>mv quoumm eeouo owe mHHHH.m H Honouoo OH H was 240e0e. $26.. 240105 tuna: .H mHCmHm 433.2m4772 HHT HHH H.IJH 1 k6 E\3 :33. 3.68%. Hm L L 00... O 00.... 00N+ 00m... 00¢... um...) ouaa JUOOJOd 25 the Red Cedar remained barren except for a brief period of growth late in summer. Dry organic weights as percentages of dry weights for individual species were not sufficiently altered by changes in season or stream water quality to warrant comparison of sites. Values are included in Appendix, Table A2. When comparing one site with another, differences in phosphorus standing crop (mg P/mz) were a function primarily of macrophyte biomass rather than of phosphorus content of the plant tissue. Similarly, percent deviations in the phosphorus standing crop from a seasonal average were almost identical to the deviations in organic standing crop (Figure 7) with the exception that there was a minor dampening in these fluctuations due to high phosphorus content in spring when dry weight standing crop was low. There was no indication that the degree of dampening was a response to changes in eutrophication levels. Standing crop of phosphorus within plant tissue is presented in Appendix, Table A3. DISCUSSION Phosphorus content in plant tissue Phosphorus content in a plant species is a function of physiological age and condition and of nutrient availa- bility (Smith, 1962). In this study the phosphorus_levels in tissue increased directly with total phosphorus concentration in the water, but this could not generally be shown with statistical reliability because of high variance. A great proportion of this variance is believed to result from variability in plant condition. Random sampling was required for a reliable estimate of standing crop of phosphorus. The disadvantage of this technique was that by not selectively sampling vegetation of a given physiological condition, the chances of detecting en- vironmentally induced differences were reduced. Eliminating this variable would probably increase the reliability of using phosphorus content in plant tissue as an indicator of phosphorus levels in a stream. Data in this study suggest that the most opportune time to apply an index of this type would be late in the growing season when tissue concentrations of the submerged 26 27 aquatic plants are most stable. This relative stability has also been indicated in studies by Gerloff and Krombholz (1966) and Caines (1965). Stake (1968) suggested that this period of stability applies to submerged species more than to emergents, which generally have more extensive underground parts. Boyd (1968) indicated that edaphic factors influence growth of many species although the extent of dependency upon the substrate for mineral nutrients is unknown. Hillman (1961) reported that roots of the floating aquatic Lemna minor probably have little influence in mineral uptake. Considering these obser- vations, it seems likely that the use of tissue analysis as an indicator of stream enrichment might most reliably be applied to floating species or submerged species with reduced roots systems. Another consideration in the choice of species would be variability of mineral content within a given species. These data suggest that species with a greater proportion of fleshy tissue exhibit less variability than species with a high percentage of cellulose fiber. If this is true, use of a species with limp stems and leaves as an indicator would increase the chances of detecting small differences with statistical reliability. For long range predictions of detrimental effects before they actually happen, comparative studies involving analysis of submerged aquatic plant tissue of a given physiological condition could yield beneficial results. 28 Nitrogen Content in plant tissue In this study percent nitrogen within plant tissue did not reflect nitrate or ammonia levels in the water. On the contrary, nitrogen content of the tissue seemed to be more closely correlated to phosphorus content. The ratio of nitrogen to phosphorus remained stable within the plants at all sites in spite of great variations of this ratio in the water. Similar nitrogen to phosphorus ratios in aquatic plant tissue were reported by Schuette and Alder (1929), Harper and Daniel (1939), Gerloff and Krombholz (1966), and Boyd (1968). Since water analyses for organic nitrogen were not performed in this study, no conclusions can be drawn involving total nitrogen concentrations in the water. However, tissue analyses for total nitrogen appear to be a most unreliable indicator of nitrate or ammonia levels within the water. Tissue levels could be expected to better reflect water concentrations in macr0phyte com— munities where nitrogen is a limiting factor, but luxury consumption of nitrogen was not demonstrated in this study. Standingycrop Biomass is thought to be less affected by eutrophication than by other physical parameters, such as solar radiation (Owens and Edwards, 1961), stream configuration, depth, and flow rate (Butcher, 1933). By 29 sampling the same 100 meter sections on each collection date the reliability of the biomass estimate, as repre- sentative of a given stream type, depended upon the subjective choice of a "typical" section to study. On the other hand, by studying the same section on a yearly basis, the chances for a more accurate estimate of the degree of seasonal fluctuation were increased. Standing crop estimates based on an entire site basis need not closely reflect levels of enrichment because of physical parameters affecting establishment and growth of plant species. Estimates based only upon areas containing vegetation also appeared to be affected by stream geometry, although to a lesser extent. From gross appearances it seemed that flow rate, which prevented growth completely in midstream, inhibited growth at the fringes of the community. It is expected that other physical parameters would similarly affect colonization by a species. For these reasons I do not believe that, under uncontrolled conditions, comparative studies of standing crops alone can produce a useful index to eutrOphication. However, when the data were analyzed on the basis of percent deviation from the seasonal average of each site, the indications were that degree of plant community fluctuation did more closely reflect levels of enrichment in a stream. The extent to which other parameters affected these values is unknown and would require further study. 30 An unresolved question was the influence of species interaction in these fluctuations. Must an index based upon degree of standing crOp fluctuation necessarily be applied at the species level or can this reliably be accomplished on a community level? This study did not lend itself well to answering that question, since all the communities, except that of the lower Jordan, were essentially monospecific. However, a comparison of the lower Jordan and AuSable Rivers suggests that species interactions affect the seasonal stability of a plant community. The AuSable community was composed primarily of Potamogeton filiformis, while the lower Jordan was dominated by P. filiformis and Elodea canadensis. The estimates of percent deviation in organic biomass from the May 1 to October 1 average for these species (Figure 8) indicated that the seasonal fluctuation of P. filiformis was greater in the AuSable than in the less eutrOphic lower Jordan. On a community level, however, fluctuations in the lower Jordan were less than in the AuSable more by reason of species interaction than by differences in fluctuation of the one species common to both streams. The increased stability resulted from seasonal differences in the growth cycle of the two species. Butcher (1933) also reported that E. canadensis overwintered longer than many Potamogeton species. Further investigation should be made into the importance of species interaction in m Hum H “.mv .mmHommm vmuomHmm How momnm>m H Honouoo on H an: Eoum HmHHmuma HCMHQ UHCmmHo Ho macho mCHvaum Ho COHHMH>mU HCmonm .m mHCmHm < H 1 §\ 3...... V. \N l \\\\\ R\\ $\\ F— 2- me e e s. w: L 00... O In I 0 00 + 00.... £535... coHoooEoHon. .533 Hemqm se. _ _ 2 «3.3. .523 L 09+ Jog/Tea waxed UOI 32 community stability. Possibly, at given levels of enrichment, a plant community would select for a species composition which would exhibit a predictable amount of seasonal fluctuation. Few stream studies involving seasonal changes in submerged macrophyte biomass have been reported. Edwards and Owens (1960) reported a June-September increase of 220% in an unpolluted stream and (Owens and Edwards, 1962) a May-July increase of 500% further downstream where nutrient levels were higher. Stake (1967) studied a small enriched creek, primarily with emergent vegetation. There Potamogeton natans, though not a dominant species, increased 110% from June to July, and decreased thereafter. On the other hand, Owens and Edwards (1961) suggested that shading had a greater influence on standing crop than did enrichment levels. These studies do not appear to have included sufficient collection dates to obtain reliable estimates of seasonal averages. It is, therefore, diffi- cult to make valid comparisons. They do, however, strongly suggest that any use of percent deviation from a seasonal mean as an index to water quality must, at a minimum, incorporate or be applied under given conditions of latitude, solar radiation, and local geographic factors. LITERATURE CITED LITERATURE CITED Anderson, R. R., R. G. Brown, and R. D. Rappley. 1965. Mineral composition of Eurasian milfoil, Myriophyllum spicatum L. Chesapeake Science, 6(1): 68-72. Boyd, C. E. 1968. Some aspects of aquatic plant ecology, p. 114—129. In Resevoir Fishery Resources Symposium. UfiIversity of Georgia Press, Athens, Georgia. Boyd, C. E. 1969a. Production, mineral nutrient ab- sorption, and biochemical assimilation by Justicia americana and Alternanthera philoxeroides. Arch. Hydrobiol., 66(2): 139-160. Boyd, C. E. 1969b. The nutritive value of three species of water weeds. Economic Botany, 23(2): 123-127. Brege, D. C. 1969. Extent of contamination of a cold- water stream by private domestic waste-disposal systems. M.S. thesis, Michigan State University, Lansing, 85 p. Butcher, R. W. 1933. Studies on the ecology of rivers. I. On the distribution of macrophytic vegetation in the rivers of Britain. Journal of Ecology, 21: 58-91. Caines, L. A. 1965. The phosphorus content of some aquatic macrophytes with special reference to seasonal fluctuation and application of phosphate fertilizers. Hydrobiologia, 25: 289-301. Edwards, R. W. and M. Owens. 1960. The effects of plants on river conditions. I. Summer crops and estimates of net productivity of macrophytes in a chalk stream. Journal of Ecology, 49: 119-126. 33 34 Forsberg, C. 1960. Subaquatic macrovegetation in Osbysjon, Djursholm. Oikos, 11: 183-199. Gerloff, G. C. 1969. Evaluating nutrient supplies for the growth of aquatic plants in natural waters, pp. 537-555. In Eutrophication: causes, conse- quences, correctives. National Academy of Sciences, Washington, D.C. Gerloff, G. C. and P. H. Krombholz. 1966. Tissue analysis as a measure of nutrient availability for the growth of angiosperm aquatic plants. Limnology and Oceanography, 11: 529-537. Gorham, E. 1953. Chemical studies on the soils and vegetation of waterlogged habitats in the English Lake District. Journal of Ecology, 41: 345-360. Harper, H. J. and H. A. Daniel. 1934. Chemical composition of certain aquatic plants. Botanical Gazette, 96: 186-189. Hillman, W. S. 1961. The Lemnaceae, or Duckweeds, a review of the descriptive and experimental liter— ature. Botanical Review, 27: 221-287. Lueck, C. H. and D. F. Boltz. 1956. Spectrophotometric study of modified heteropoly blue method for phosphorus. Analytical Chemistry, 28(7): 1168-1171. Misra. R. D. 1938. Edaphic factors in the distribution of aquatic plants in the English Lakes. Journal of Ecology, 26: 411-451. Owens, M. and R. W. Edwards. 1961. The effects of plants on river conditions. II. Further crop studies and estimates of net productivity of macrophytes in a chalk stream. Journal of Ecology, 49: 119-126. Owens, M. and R. W. Edwards. 1962. The effects of plants on river conditions. III. Crop studies and estimates of net productivity of macrophytes in four streams in southern England. Journal of Ecology, 50: 157-162. Rickey, G. F. and A. W. Avens. 1955. Photometric determination of total phosphorus in feeding stuffs and fertilizers. Association of Official Agri— cultural Chemists, 38(4): 898-903. 35 Schuette, H. A. and H. Alder. 1927. Notes on the chemical composition of some of the larger aquatic plants of Lake Mendota. II. Vallisneria and Potamogeton. Wisconsin Academy of Science, Arts, and Letters, 23: 249-254. Schuette, H. A. and H. Alder. 1929. A note on the chemical composition of Chara from Green Lake, Wisconsin. Wisconsin Academy of Science, Arts, and Letters, 24: 141-145. Schuette, H. A. and A. E. Hoffman. 1921. Notes on the chemical composition of some of the larger aquatic plants of Lake Mendota. I. Cladophora and Myriophyllum. Wisconsin Academy of SEIence, Arts, and Letters, 20: 529-531. Smith, P. F. 1962. Mineral analyses of plant tissues. Annual Review of Plant Physiology: 13: 81-108. Stake, E. 1967. Higher vegetation and nitrogen in a rivulet in central Sweden. Schweitzerische Zeitschrift fur Hydrologie, 29: 107-124. Stake, E. 1968. Higher vegetation and phosphorus in a small stream in central Sweden. Schweitzerische Zeitschrift fur Hydrologie, 30: 353-374. Weatherly, A. and A. G. Nicholls. 1955. The effects of artificial enrichment of a lake. Australian Journal of Marine and Freshwater Research, 6: 443-466. APPENDIX 36 .muHm mpsum Hm>Hm CMCHOU Hmmma mo mmCoN mCHHmEmm oCm .CoHumooH .CoHumHCmHmCoo mCHsoCm mmE mHmow .H¢ mHCmHm mN m 0 Ill-Ill HEH Boom . Se e822: gee.z_me._m.eees\_;z. «.2 ..\. m . ., \e \ ‘ A \\\ s H 37 .muHm mosum Hw>Hm Cmpuon H030H Ho mMCoN mCHHmEMm oCm .COHumooH .COHHMHCUHHCOU mCHzoCm awe OHCUm .NC oHCmHm mm D O .IIIII‘IIIIJIIIIIIIIIJ-I-I- :5 Boom see .52 Home :s 32 3. 32 A. \\ \ x \. \\\\WW\\\\\\\\\\.\.\NH\.\\. ..\\ .\....\.........\.\\,. .m\ \\.H.,,\\. . . SARx. \....\... Vm . \ .,....\. .\ \\ . few \\.. \x. .q.\. .\ x. e \.,..\..w \V. .\\\ \ .. .eexg \ \x. .. \ . fl... _..\ .... \ \..\.. ...\ .e..\\....\\\A. \ \\ Z 38 .muHm mwsum Hm>Hm oHnmmC< mo mCoN mCHHmEmm CCm .COHHMOOH .CoHumquHmCoo mCHzoCm awe mHmum .mC mHCmHm HUN 0 0 IIIIIIIII E. 225 .2... 535.2 2.2. .zoee .993 38.58 m .mHHm mpsum Hm>Hm Hmpmu pom mo mmCoN mCHHmEMm UCm .CoHumooH .CoHumudewCoo mCH30Cm mmE mHmom .e< wHCqu mm m 0 III-III II .6. 23m .2... 535.: see .23 .eeoeeé. “5:32 39 sex“... :.. ...x x.... .x. xx)... ....x xx. . x x\.. x . \§\.\.wxxx.x.\.\\ .. .x \ xx .x..\ x..x\.....\\\Wo.\.\\“vx\.\x\\\.\\vx\ \ .xx.... .\.\ \....\\\x\.x ..x .\x \\x \ \.\\\ .x \.\ .H...........H.....m\\\\ee\.\ .x..\.\. .\.x , . .§%§e®®e\x . . exx . \x. xx .. . .xx ....x xx.\..x\..x\ x . HE. .. . e H .. ,.. \.x\......> . x. . . . e . T . . . be}? .5 x. . 3.3:. H . . . ._... I. .J. 40 Statistical formulas 1. Estimate of mean and variance for standing crop within colonized areas, percent nitrogen, percent phosphorus, percent phosphorus, and percent ash-free of dried plant material were determined by conventional parametric statistics: Where x. is the ith estimate of parameter in question, 1 n is number of estimates taken, mean = in/n with variance = x-xi)2/(n-l) l IIMD ( l 2. Standing crop of dried plant material for entire study site was estimated as follows: Where b is proportion of total site within sampling area, N is total number of samples taken, n is number of samples containing plant material x. is dry weight of ith sample (including only those samples containing vegetation), p = n/N mean = bpi with variance = bzp [Si x2(l-p)]/N 41 3. Standing crop of phosphorus was estimated as follows: Where x is estimate of mean dry weight standing crOp within entire study site, y is estimate of (mean percent phosphorus in dry plant materia1)/100 mean = xy with variance of the mean = §Zs§-+ yzsé 4. Percent river bottom colonized by plants was estimated according to the binomial distribution: Where b is proportion of total site within sampling zone n number of samples containing plants N total number of samples taken with variance = b2p(l-p)/N 42 .Hmwmu pom n 0 “CMUHOb Ho3oH u m “Cmpuon Hmmma u «m eo.Hee. Ho.Hmo. eo.Heo. Ho.Heo. He.Heo. mo.Heo. Ho.Hmo. e eHHeeHs> mango em. mH.Hee. mo.Hme. ee.HHm. e .ee msHooesoee ee.H om.Hem.H oe.HeH.H o aseHoEOo ECHHmCmoumumU mm. a mCHMCHuomm CouomOEmuom oexe mexe mexe eexe mxe eexmxm eexHexe eoo>HA moHooem mHmp .H.U mom H x .muHm mCo Cmnu mHoE 0H COEEoo HOC mmHoomm How mammHH quHm UOHHU Cm>o Ho mCHOCmmOCm quoumm .H4 mqmfle 43 .m.eHme .e.eHee oexe .m.mHme .m.H+me eer .e.H+He .H. ee mexe mHoeeHoe mHHeoeHe .m.H+oe eexe .H. mu er msuocHuooo .m .m.HHoe .m.mHee .m.HHme oexe .m.eHme .m.eHee .m.e+ee eer .m.mHoe .m.mHoe mexe .m.eHoe .m.H+He mexe He.HHee .H. me mxe .m.o+ee .H. me eme T .H. Tee exm .m.eHme .e.eHHe eexer .e.m+ee .m.e+ee eeerxe eHEeoHHHHe .e .e.mHoe .H. Tee oexe .m.eHee .m.m+ee eer .m.eHee .H. ee mexe .m.HHHe .H. on mexe .m.eHee .H. ee mxe .e.eHee mem .m.m+ee T oexer .H. me .e.H+ee eeerxe esoeeuo :oeoeoseooe Cmpmo com oHQmmsm CMCHOb Cannon mump mmHommm H03OH Comm: H0>Hm ..o. mm H H x .mmuHm Emmnum HCOH Hm HMHHmHmE HCMHQ COHHU Co>o mo mquHm3 mwum Cmm HConmm .Nm mHmCB 44 .H. Tee .e.eHee He.e+ee .e.Hmee .m.e+mH .m.emee .e.e+ee .H. ee .e.oHee .H. He .e.eHHe .m.emmm He.e+mm .H. ee HH. ee .m.eHee .m.oHee .e.HHee .e.oHoe .e.eHme .mVeHme .m.mHee .m.eHee .e.H+ee .e.Hmmm Hmvfime HmVN+vm Hm. omeem HMHDHmm .m.eHoe Hm.NHem .e.H+mm .m.emHe .e.H+ee .m.emee .e.e+ee .H. mm om\m mH\m mm\h mm\m m\m mH\m m\m mm\mH\m exOH eexe er m\OH H\m oexe eer mexe mexe mxe mem exm oexer eexoexe mHHmmHC> mumsu ECmHmEmp ECHHHCmoumumu HHHeouoe eooon mH mCOCMCMU MOUOH m 45 TABLE A3. Standing crops of phosphorus (mg P/m2) at four stream sites. X : 1 SE. River upper lower date Jordan Jordan AuSable Red Cedar 9/21/69 13:3 19:4 328:82 2/1/70 16:6 23:10 5/3 9:3 6:1 4: 2 5/15 14:4 4:1 13: 3 6/5 7:2 3:1 26: 6 6/26 11:2 12:4 57:14 7/23 12:4 15:4 128:33 l.5:0.5 8/23 9:2 13:4 215:40 8.0:2.l 9/20 15:4 8:2 153:33 2.7:O.9 MICHIGAN STRTE UNIV. LIBRARIES I ll MINI llfllllllli HI 312931027 2476