PRODUCTIVITY OF AQUATIC MACROPHYTES AT ERIE MARSH Thesis for the Degree of M. S. MICHIGAN STATE UNIVERSTIY .Peter H. Rich 1966 ‘ CM! LIBRA R Y Michigan State University IIIIIIIIIIII IIIHUIHHIIHJIIHIIUIIIIIIIIIIIIIIIIIIIII L 3 1293 10696 1083 PRODUCTIVITY OF AQUATIC MACROPHYTES AT ERIE MARSH BY Peter H. Rich A THESIS Submitted to Michigan State University in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE Department of Zoology 1966 ACKNOWLEDGEMENTS My first acknowledgement goes to Dr. Peter I. Tack who always had time and attention for this project. Dr. John E. Cantlon and Dr. Miles D° Pirnie generously contri- buted guidance and ideas in the course of many very rewarding discussions. I am also grateful to Dr. T. Wayne Porter who read the manUScript with an editor's eye and who contributed to my Master's program in many ways. Dr. Stephen Stephenson substituted for Dr. Cantlon during the preparation of the manuscript. Dr. William E. Cooper criticized the statistical techniques, and I attri— bute what should be a lucid statistical presentation to his efforts. I acknowledge special thanks to the Soil Science Department for making equipment and facilities available to me. I also take this Opportunity to thank Mr. Don Christenson. of the SoiI Testing Laboratory for helping me interpret the results of the soil tests. Financial assistance was provided by the Erie Research Committee and the Wildlife Management Institute. ii I wish to thank the manager, Mr. Kenneth Reau, and the members of the Erie Shooting Club for the use of their facilities. I am much indebted to Mr. Dennis R. King who made his daily records from the marsh available to me. Mr. King also granted me permission to reproduce Table 2 of his thesis. My thanks to all the others who helped, including William Gulish, Herbert Lennon, Robert Lippson, and Ronald White. Finally, I must exPress my appreciation to my wife, Nancy, who spent many, many hours sorting samples. iii TABLE OF CONTENTS LIST OF TABLES . . . . . . . . . . . . . . LIST OF FIGURES . . . . . . . . . . . . Chapter I. DESCRIPTION OF STUDY AREA . . .7. II. MATERIALS AND METHODS . . . . . . III. RESULTS AND DISCUSSION . . . . . . IV. FISH IN THE SAGO SAMPLE AREA . . . V. INVERTEBRATES IN THE SAMPLE AREAS VI. CARP AND TURBIDITY . . . . . . . . VII. CONCLUSIONS . . . . . . . . . . . LITERATURE CITED . . . . . . . . . . . . . APPENDIXI................ APPENDIX II . . . . . . . . . . . . . . . APPENDIX III . . . . . . . . . . . . . . . iv Page vii 13 25 71 76 78 96 98 101 102 103 Table 10. 11. 12. 13a. 13b. LIST OF TABLES Water Levels and Temperatures Recorded at Boathouse Dock . . . . . . . . . . . . Summer Carp Food Habits in Erie Marsh in 1964 O O O O O O O O O O O O O I O O O O Exclosure Data for the Sago Sample Area . . Transformed Exclosure Data for the Sago Sample Area . . . . . . . . . . . . . . . Analysis of Variance of the Transformed Exclosure Data from the Sago Sample Area. Exclosure Data for the Sago Sample Area . . Transformed Exclosure Data for the Crispus Sample Area . . . . . . . . . . . . . . . Analysis of Variance of the Transformed Exclosure Data from the Crispus Sample Area 0 O O O O O O O O O O O O O O O O 0 Plant Material in the Bottom Samples . . . Sampling Error . . . . . . . . . . . . . . Depth Data used in the Analysis of Variance Analysis of Variance of the Depth Data . . Productivity Data for the Sago Sample Area. Transformed Productivity Data for the Sago Sample Area . . . . . . . . . . . . . . . V Page 10 28 34 35 38 39 40 43 47 48 55 56 65 65 Table 14a. 14b. 15. 16. 17. LIST OF TABLES Productivity Data for the Crispus Sample Area 0 O O O O O O O O O O O O O O O O Transformed Productivity Data for the Crispus Sample Area . . . . . . . . . Productivity Calculations for 1965 Samples Seed and Winter Leaf Bud Production . . Fish Near the Sago Sample Area . . . . . vi Page 67 67 69 70 74 7a. 7b. 8a. 8b. 10. 11. 12. LIST OF FIGURES Page Map of the Erie Marsh . . . . . . . . . 4 Soils Map of the Erie Shooting Club . . 5 Pump in Operation at the Weir . . . . . 9 Diagram of the Sample Areas 1964 . . . 15 The Sago Exclosures . . . . . . . . . 16 The Crispus Exclosures . . . . . . . . 16 Loglo Organic Weight/Time Sago Area Controls. 36 Log10 Organic Weight/Time Sago Area Exclosures . . . . . . . . . . . . . 37 Loglo Organic Weight/Time CrisPus Area Controls . . . . . . . . . . . . . . 41 Log10 Organic Weight/Time CrisPus Area Exclosures . . . . . . . . . . . . 42 Cladophora on Sago Exclosure #2 . . . 44 Depth Data from the Sample Areas . . 54 Depth Data: Mean of Replications/Samples 57 Log10 Organic Weight/Time Sago Controls 1965. 66 Log10 Organic Weight/Time CriSpus Controls 1965 . . . . . . . . . . . . . . . . . . . 68 vii I. DESCRIPTION OF THE STUDY AREA The Erie Shooting Club Marsh is located in the extreme southeastern corner of Michigan. It is in Monroe County, near the town of Erie. According to the United States Public Lands System the marsh is placed at TBS; R8E; Sections 14, 15, 21-23, and 26-28. Except for man- made features such as dikes, roadbeds, and overpasses, the area has no relief and very little elevation above modern Lake Erie. The soils in the area represent sediments of lakes ancestral to Lake Erie, and most of the land in the neighborhood is cultivated. The marsh is essentially a diked-in portion of littoral Lake Erie. The sample areas are in North Bay (Sections 22 and 23) which was isolated from Lake Erie with the completion of the East Dike in the Spring of 1953. Previously North Bay had been part of Maumee Bay, protected from the lake by Woodtick Penninsula. The bays enclosed by the outer dikes brought the total area of the marsh up to its present figure, approximately 1000 acres. Since 1957 the Erie Research Committee and the l 2 Wildlife Management Foundation have Sponsored research in the marsh. The first four years were supervised by Dr. George S. Hunt of the University of Michigan; the next four years by Dr. Miles D. Pirnie of Michigan State University. In 1964 and 1965 Mr. Dennis R. King from U of M and I worked in the marsh under our respective pro- grams. The information gathered in the period since 1957 is available in a series of annual reports submitted to the Erie Research Committee, including a summary pre— pared in 1964 by Dr. Pirnie and Mr. John Foster. Location of the sample areas: North Bay is bounded on north and east by the East Dike, on the south by Sand Island and East Bay, and on the west by Secor's Unit and the mainland. Except for a deep area at the extreme north end, North Bay is uniformly shallow. King (1965: 10) approximated the depths as between 10 and 17 inches at summer water levels, i.e. 2.0 inches at the Boathouse Dock gauge. The two sample areas are located in the southern end of the bay, near Sand Island. The locations were chosen on the advice of Dr. Pirnie and Dr. Cantlon who detected differences in the species composition be- tween the two sides of the bay. In fact, it was possible 3 during the summers of 1964 and 1965 to recognize a definite boundary between the two provinces. In 1964, prior to installing the exclosures, the boundary shown in Figure l was determined by rowing back and forth over the area and dropping a stake each time the dominant plant changed. The two sample areas were lined up on an east-west axis and then placed approximately equidis- tant between the province boundary and the shore. The western site, characterized by a predominance of curly- 1eaved, criSpus pondweéd (Potamogeton crispus L.), was offset toward the center of the bay somewhat to assure that it remained in the same soil province (see Figure 2)° The eastern sample area is characterized by the presence of sago pondweed (P, pectinatus L.). The "Crispus" area is approximately 1 1/2 inches shallower than the "Sago" area. o~ Bottom material in the sample areas: The soil map (Figure 2) was drawn by Carl F. Eby in 1958, and he turned in a detailed soil report to the Erie Committee in 1959 (Eby, 1959). The map shows North Bay to contain several soils. However, both sample areas are in the 7771 province, described as marl over organic matter. mxflo Epsom mom fivsom _ \\\S s a Q ® Q \\ ’ Q” I Q Q .1 C \\ I III/ Q Q P G W \ ”1| ’ O § .m \ ueflom dunno , c Q moCQHmH c s hmm ummm Q ., WW. I K c Q 302 mtcmHmH ac h a I I mm ”x UHO c Q 4/ mm: a a z \I \III I “U .. cl mSOSHM M I \. I... .I IINUHHGD \I .III\‘ I I /\ e m ,. , it... a. A» x I...” .m m. . .HMSWD W M/m/bom/ \ E a m _ I . / // / x S CON . s I II I/\\\ e am“. — aI I ’\J h e \ I. , n... a t h I” I .\ 1H lo f t Dllllf\ I. II 0 3m IIfl I, \\ |” ‘\ P ommm \....\\ am 3&3 . - .. mamas 1 a . m.umuuom c 4 e O . l . . . .330“. .m 5.2. m. e so}: . 255 .92 .5 w... .m . nwm. 2:... ou£>om . C . « unqom , .oom xomaa< .._ Deflom hsoum 1 how. .<.o.m.: Immdi Emu mozEnm man—43m :3 30.3.3 3(3 mass new Em; m mnmm m...mw>._:o I Am . >6 mm m mz_ .II 2 ..N\.H @H u mummwuu II .mH H. 0 mm 29552; :34: MW e I . n\ ’ mwvzo II. . Il\\.. . mmmum mHmEmm mo ~3th mumefixoummm mo m.mo m.mm mmusumumdsCu maeucos cams mama NH 3H m k as mama sesoao mama s as ma ma RH sesoflo sauumm mama HA 6 s m N mama Hmeo masocfl Hm.H om.m mm.H km.~ om.m coaumuamsumum s3982 mom.~o m.so m.m> $.66 m.mm mmusumsomsCu manucoz HTQEoummm umsmdfi Mann scab hm: aoma moms mpoflumm meEmm on» mcwudn GOHHTEH0mcH ucmsfluumm II. MATERIALS AND METHODS Two major objectives were sought in this study. First, the effect of carp on the standing crop of aquatic macrOphytes in the open water areas of the marsh was estimated, and, second, a macrophyte productivity esti- mate was made so that any measurable effect of carp could be put on an absolute basis. The estimate of carp effect was based on an exclosure and control area study. Macrophyte productivity was estimated by measur- ing standing crop at the beginning and the peak of the growing season. The exclosures: The exclosures were constructed of 1 1/2 inch poultry netting, 5 feet in width. The dimen- sions of the exclosures were 2 by 4 meters, with a stake supporting the wire at“2 meter intervals, i.e. 3 stakes on each long side. The stakes were 8 foot 1 by 4's. The exclosures and controls were oriented on a north- south axis and arranged as shown on the sampling diagram of the two areas (Figure 4). A total of 6 exclosures were constructed, 3 in each sample area. 13 14 The installation of the exclosures was the big- gest problem encountered during the whole project and delayed sampling by about 3 weeks. The first attempt at installation, using a prefabricated exclosure, was a failure. The substrate in the sample area is so soft that it is difficult to get any leverage on the wire and stakes to place them in position. Although this method is not impossible, I decided that it inflicted too much damage upon the substrate. A second attempt, using prefabricated sides only, was a great improvement, but still unsatisfactory. I did not feel that secure seams could be made under- water with a hammer and fence staples. Two exclosures were installed in this manner, however. Finally a method was discovered that was both quick and effective. A 1/2 indh staple gun was pur- chased for the purpose of fastening the wire underwater. This worked so well that these staples were used for all fastenings, both in and out of water. The only Opera- tions necessary ashore were the cutting of the wire to the correct dimensions and folding up the bottom one foot, so that later, after the wire had been installed, 15 Diagram of sample areas 1964, with dates of installation of exclosures (below figures) (B) (l) (removed 9/16) 9.. .1 Meters % r-*—-1 | 8/19* (SI 9/9 ' (D) L__4__J V 8/24* IEI 9/10* (4) Figure 4. and sampling dates (enclosed). Contra. _a_r___a. Exclgsure | 8/4* I 8/5* I 8/25 I (C) 8/26 9/16* 9/15* L-— _..+ __ - 8/5* I 8/4* I 8/26 (3) I ' 8/25 I 9/15* .' 9/16* I SAGO SAMPLE AREA E North 4 i S W T"‘ ‘““ "'1 Y | 8/19* | (F) 8/24* 9/9* 9/10* 1 -— — 0- - J ‘ 8/24* (6) 8/19* ' 9/10* I 9/9* : L— — —-O .._ — J 7/30 7/30 CRISPUS SAMPLE AREA (removed 9/14) *Bottom samples also taken. l6 ~ Figure 5: The Sago Exclosures, looking north, September 9. 1964. ._ __ _ __.—. - ___ _ __~___ Figure 6: The CrisPus Exclosures, looking north, September 9, 1964. 17 it could be pressed into the mud to form a burrow-proof apron. At a sample area it was necessary only to drive the stakes, which could be done from the boat with no danger of disturbing the bottom, and then hang the wire which can be done from the outside, again with no danger of disturbing the area actually sampled. Becauée the staple gun was heavily chromed, the only parts liable to corrosion were the spring feed for the staples, the large driving spring, and the staples themselves. The only maintenance necessary on the gun consisted of removing and discarding any unused staples at the end of a day, shaking out all the water possible, and rinsing the gun off with outboard gas. Anyone inter- ested in this device might investigate larger models using larger and heavier staples, particularly where the staples would be exposed to harsher conditions for a longer duration. It was apparent during the demolition of the exclosures that those fastened with the staple gun were tougher than the two fastened with hammer driven fence staples. The actual fastening can only be as strong as the strand of wire it fastens, and the gun staples were quite sufficient in this respect. Because the staple 18 gun is quick and easy, it is possible to triple the number of fastenings on a seam and still save time. The controls: The controls were staked out in the same manner as the exclosures, but they were not enclosed with netting. Because I had to walk around the exclo- sure to install the wire, I also made a path around each of the controls. This was done to reduce the prob— ability of spurious treatment effects resulting from the disturbance inherent in the installation of the exclosures. Plant sampling technique: The samples were taken from a 1/4 square meter wooden frame. The frame was 1/2 meter on a side, with legs projecting down from the corners to hold the frame in place. Although the frame was buoyant, the mud held the legs firmly once the frame was pushed into place against the bottom. Four such sub-samples were taken from each exclosure and con- trol on a sampling date. Thanks to the properties of both the mud and the plants, rather accurate sampling was probably achieved in spite of the extreme turbidity which necessitated do- ing everything by touch. When a plant leaned out of the 19 sample area, causing the main part to be excluded by the frame, I discovered that the plant would slide back under the frame when the roots inside were pulled up. When, on the other hand, the plant leaned into the sample area and was pulled from the top rather than from the bottom, the stem simply broke off at the edge of the frame. Washing and transportation of the plant samples: The samples were washed in a wooden box with a window screen- ing (16 mesh to the inch) bottom at the time they were taken. The samples were subsequently stored in ll-quart plastic pails until sorted. For convenience, the screened box was made 1/2 meter on a side so that it could be used as a measuring device to help position the sampling frame in an exclosure or control area. In order to completely remove the rather tena- cious bottom material from those plants with roots, the plants were washed vigorously. This led to sorting diffi- culties as the washing fragmented and tangled the plants and plastered sago pondweed debris over everything. The washing also removed most of the silt and/or periphyton which covered the plants in the extremely turbid water. 20 The first samples from both the Sago and CriSpus areas were sorted almost immediately, and no samples re- mained unsorted for more than 24 hours. In this case, the pails were kept full of water. mAt the time of the second Sago sample, the weather made it necessary to take the samples as rapidly as possible, with sorting delayed for up to 48 hours. After 24 hours the plants developed a bad odor and became blackened. 'These samples were drained at that time, and thereafter samples were kept moist but drained at all times. Hopefully, this kept the plants alive and prevented decomposition. The last samples in 1964 from the Sago area were taken at the last possible moment before the exclosures had to be removed. This meant that the exclosures were removed before sorting started. The samples, themselves, were extremely tedious to sort. All this resulted in very long wet storage times, as follow: Sample #1 - 48 hours 2 - 72 hours A and B - 72 hours C - 96 hours 3 - 144 hours After sorting, the plants were dried on newspaper and placed in paper bags. The drying process never took more than 12 hours, although an additional 12 hours were 21 allowed. The bags were stored in a dry, unheated build- ing until oven dried for dry weight and organic weight determinations. Oven drying of plant samples: The plants were dried at 1700F in a forced air, electrically heated, drying oven provided by the Soil Science Department. The 1964 sam— ples were dried for 48 hours, and the 1965 samples for 72 hours. The drying times in both years were far in excess of the times used for the same amount of much tougher terrestrial plants for which the oven is regu- larly used. Samples weighing less than one-tenth of a gram were called "trace," and were calculated at a value of 0.05 grams in both dry and organic weight figures. Some samples were re-weighed at the end of the weighing procedure to determine the effects of atmOSpheric mois- ture upon the eXposed samples. "The results were slight (0-3%), and, although some error was undoubtably intro— duced, the effect was ignored. Organic weight: The dried samples were sorted for seeds and Winter leaf buds, then ground in a manually Operated corn grinder. Sub-samples of the ground material, never less than 75% of the total material, were redried at 105°C, 22 weighed, and burned in a muffle furnace at 550°C. The ash weight was subtracted from the 105°C dry weight to determine organic weight. The organic weight was then divided by the 105°C dry weight to produce a quotient. The quotient was multiplied by the 170°F dry weight (minus the weight of seeds and Winter leaf buds) to give total organic weight for the foliage.” Seeds and Winter buds received the same treatment except these smaller samples did not have to be ground and sub-sampled. The total organic weights appearing in the statistical analyses represent the sum of seeds, Winter leaf buds, and foliage. Bottom samples: Samples were taken with a 6 inch Ekman dredge inside the plant sampling frame after the plants had been removed. Each sample consists of two sub- samples, one from the north and one from the south end of each exclosure and control area. The samples were washed in the same screen lined box that the plant samples were washed in. My ignorance of statistical techniques at the time led me to lump together all the samples from each sample area. Thus, no error term can be computed for these data. The samples were stored in approximately 10% formaldehyde until sorted, a period ranging between 3 23 and 18 months. The bottom samples.were‘sorted into seeds, Winter leaf buds, and foliage for each species. They were dried, weighed, burned, and weighed as previously described to get organic weight. These weights were then multiplied by a factor (21.6) to make the 1/2 square foot per repli- cation they actually repreSent equivalent to the one square meter per replication the plant samples represent (Table 9). Dgpth data: The sounding data was taken on September 8, 1964. At that time the water level gauge at the Boat- house Dock registered 2.28 inches. The data were taken under ideal conditions, with glassy calm water and with the exclosure and control stakes in place to provide a rigid and accurate grid. The measurements were made to 1/4 of an inch with a yard stick tipped with a 20 cm. metal disk. The disk made it possible to sense the very soft mud-water interface. Care was also taken to avoid paths made in the bottom during the construction of the exclosures. Sampling techniques in 1965 (The productivity study): In 1965 plant sampling differed from that mentioned pre- 24 viously because no exclosures were installed and no control areas were staked out. The sub—sampling arrangement was the same, and the same number of control samples were taken at each sampling area. There were no exclosure samples. A sample consisted of four, one-quarter meter sub-samples taken while swinging about an anchor. Follow- ing this, the anchor was raised and then released a few oar strokes to the north for the second sample. In this manner the samples remained on a north-south axis in the sample areas as they were in 1964.. The plants were treated like those in 1964 in all other resPects. Wet storage times were kept to 24 hours. Soil analysis: The differences in the appearance of the bottom material between the two sample areas prompted me to have a soil test performed to determine physical (mechanical) properties and fertility. One bottom sample from each area was analyzed by the Soil Testing Laboratory at Michigan State University. The samples were taken on September 8, 1964 with an Ekman: dredge. The results appear in Appendix I. III. RESULTS AND DISCUSSION The exclosure study: The exclosure study was undertaken to detect the direct effects of carp upon the vegetation. Unlike the study by Threinen and Helm (1954) in which a 75 acre bay was fenced off, the exclosures did not pro- tect the vegetation from the indirect effects of carp, i.e. turbidity and silt deposition. These effects are discussed in Chapter VI. Probably the most important direct effect of carp is the mechanical uprooting of the plants (King, 1965:95). The uprooting is apparently caused by the bottom feeding activity of carp which is known to produce significant changes in the bottom (see: The analysis of the depth data). In 1958 Dr. Hunt (1958:23) stated that the application of toxaphene that year and the resulting destruction of carp eliminated uprooted plants in the bays. In 1961 Bennett, Matulis and Drum (1961:5-6), recorded the presence of win— dows of sago pondweed and wild celery on the shores of the bays. They observed that the plants were unmarked and that their roots were intact. Examination of the growing 25 26 plants in the bays revealed that they were firmly rooted, but that large holes with interconnecting channels were present in the vegetation. They concluded that carp were grazing in the area. In 1963 Foster (1963:5) also ob- served uprooted plants. King (I965:96) has an excellent color photograph of windroWed vegetation in East Bay. The other direct effect which carp inflict upon the vegetation in the marsh results from their utilization of some species for food. In 1963 Foster (1964:5-6) examined the stomach contents of 12 carp: six taken over EREEE and six taken over pondweeds, algae and dead cat- tails. Four of the carp taken over gh§£§_contained nggg, but only algae was identified from the fish collected over pondweeds. In the Spring and Summer of 1964, King (1965:34, 43—45) examined 24 carp: 15 taken over EDEEE and 9 taken over pondweeds. Of the contents taken over ghggg, he dis- covered 45.7% (by volume) ghgpg, The contents taken over pondweeds were not so conclusive, but they do indicate some utilization of pondweeds by carp. King's data from the 9 carp taken over pondweeds are reproduced in Table 2 with his permission. 27 Analysis of the exclosure data: The two sample areas were analyzed separately because they represent two distinct plant associations, with different species compositions and dominants. The analysis consists of a three-way anal- ysis of variance of the organic weight data. Treatments (A) consist of exclosures (A1) and controls (A2). There are three important species (B) intflmaSago area and four in the CriSpus area. In addition to the important species is an "others" category in both samples which contains the balance of minor Species. The time (C) intervals between samples are approximately 20 days. Three samples were taken in the Sago area and only‘two in the Crispus area. There are three replications, each representing four sub— samples. An assumption of variance homogeneity could 223 be verified for the raw data. Means and variances in both areas were found to be directly related. Consequently, a log transformation was made on both sets of data. In both cases the raw data was multiplied by 10 to prevent obser- vations with values of less than one from producing nega- tive logarithms. Barlett's Test for variance homogeneity is not applicable to these data due to the small number of replications. The Box Modification is available, however 28 Table 2. Summer carp food habits in Erie Marsh in 19641.. (Nine carp taken over pondweeds June 29.) Total Vol. Percent Percent Food Item ml. Volume Occur. Total Plant 93.60 57.8 100 Sago leaves 3.53 2.2 33 Crispus leaves 0.75 0.5 9 leaf fragments 16.22 10.0 33 stem fragments 7.60 4.7 22 root fragments 3.33 2.1 22 CrisPus winter leaf buds 12.05 7.4 67 Scirpus validus seeds 1.38 0.8 33 Polygonum lapathi- folium seeds 0.33 0.2 9 filamentous algae 1.30 0.8 33 other 47.11 29.1 91 Total Animal 9.30 5.7 100 Unidentified (mucus) 59.10 36.5 100 Total 160.00 1Reproduced in part from King, 1965:44, Table 2. 29 the simple, non-parametric Corner Test of the transformed data was so far from significance that the complicated parametric test was considered unnecessary. The data conform to a mixed model. The treatments (A) represent a fixed component of variance, while Species (B) and time (C) are considered random. The estimated mean sums of squares (EMSS) are shown in Appendix II. The only factor found to be significant is species (B), which only reflects the phenomenon of dominance within the vegetation. All the other factors and interactions are not significant at the 5%.1evel. In 1964 and 1965, King (1965) analyzed the effects of exclosures upon the wet weights of vegetation at five and four locations in the marsh, respectively. Sampling occurred four times during the growing season. In an anal- ysis of variance of his 1964 data, using each of his 20 samples as blocks, treatments are heterogeneous at the 5% level. The differences within blocks are significant at the 1%.level (Op. cit. p. 49, Table 5). In the analysis of his 1965 data, 16 blocks, the treatments are different at the 1% level, and differences within blocks are not significant (Op. cit. p. 51, Table 7). In spite of replicated samples within a more ,30 limited area, which my data represent and which should pro- vide greater testing precision, it is not clear that my results refute King's. In the first place, King was pri- marily interested in the effects of carp and possibly biased his choice of sample areas. On the other hand, my observations were confined to the south end of North Bay; an area chosen for its apparent homogeneity and lack of concentrated carp activity.’ Second, only two of the five areas analyzed by King in 1964 were in pondweeds, and both showed very little or even negative differences be- tween exclosures and controls (King, 1965:48, Table 4). The area in dense ghg£g_showed much greater differences, which may reflect the preference for th£§_by carp sug- gested in the two stomach analySes. Third, my data was taken over a more limited time than Kings's, and King reported a reduction of the effect of carp during at least part of that period. King discovered that an analysis of variance of his 1964 data for the lst, 2nd and 4th samples from each sample area was significant at the 2.5% level (Op. cit., p. 58, Table 9), while his test for all samples was only significant to the 5% level. As he pointed out, the decreased degrees of freedom of his test on the lst, 2nd, and 4th samples would tend to decrease significance 31 (Op. cit., p. 59). Thus, there is an indication that carp produce a greater effect early and late in the growing season, with a lesser effect sometime between the middle of June and the middle of August. King (Op. cit., p. 67) attributes the early season effect to intense breeding activity by carp and to the vulnerability of young plants which Robel (1951) also suggests. The question remains, however, as to why my final samples, which were taken later than King's, do not show significance. I attribute the lack of significance at my sample areas to an absence of carp during most of the sample period. I did not observe any of the effects of carp upon the vegetation described by Bennett, Matulis, and Drum (1961:5-6) until late"August and early September. At that time holes began to appear in the vegetation near the samples, and uprooted plants became noticable. The ultimate purpose of the exclosure study was to determine the rate of turnover at the sample areas. Turnover represents the rate at which biomass is crOpped— off or otherwise removed during the growth period, and its significance to a productivity determination is dis- cussed in more detail in the section on productivity. Because significant differences failed to deve10pe be- 32 tween the exclosures and controls in 1964 suggests the conclusion that turnover is absent at the sampling sites in North Bay. However, the data used for the productivity estimate was taken in 1965, and King (1965:57) stated that carp had a greater effect in that year. If this is true, and if the effect was felt at my sample areas, I may not be able to assume negligible turnover in 1965. King based his conclusion upon his statistical analysis. He achieved greater significance in 1965 than in 1964: 1% in 1965 compared to 5%.in 1964. He also stated that he observed more and bigger carp in 1965 (Op. cit., p. 90). He suggested that the greater effect in 1965 resulted from both increased carp pOpulation and increased pondweed production that'year which caused the carp to be less selective for 922523 However, as King pointed out (Op. cit., p. 57), a bias occurred in his samples in 1965 which was not present in 1964. In 1964 he placed only 2 out of 5 of his exclosures in EEEEE as Opposed to 3 out of 4 in 1965. His sample area #5' (1965) (1965:50, Table 5) showed greater significance than #5 (1964) (Op. cit., p. 48, Table 4), and this leads me to believe that the carp did, indeed, reach the pondweed areas in North Bay earlier in 1965 than in 1964° 33 A filamentous alga' (Cladophora) colonized the sides of all three Sago exclosures sometime between the second and third sample period (Figure 9). However, it was only present in the samples in small amounts (2.0 grams/m? organic weight). 34 Table 3. Exclosure data for the Sago sample area. organic weight in grams (55 Doc). Y: Dates (C) Treatment (A) Species (B)* 8/4-5 8/25-26 9/15-16 2, pectinatus 18.5 11.6 3.5 32.2 18.4 8.3 6.9 5.6 1.3 Elodea ” 38.8 29.8 27.5 canadensis 57.5 29.9 25.0 58.5 32.1 31.0 Exclosures P, foliosus 4.9 0.3 5.7 2.5 2.1 1.6 1.9 0.4 2.9 others 7.0 5.3 7.7 13.7 3.9 12.6 6.9 3.6 13.6 .P. pectinatus 16.4 4.0 3.6 10.1 2.0 0.9 7.2 4.3 0.2 Elodea 20.6 22.5 24.4 canadensis 27.8 14.7 5.8 67.8 49.2 39.8 Controls 'P. foliosus 1.2 1.9 15.1 I 2.9 5.7 7.4 1.2 0.6 0.4 others 9.7 7.9 5.6 5.0 0.4 0.3 2.3 3.9 0.4 *Reference: Gray's Manual of Botany, 8th Ed. 35 Table 4. Transformed exclosure data for the Sago sample area. Y = loglo(lOY) m Dates (C) Treatment (A) Species (B) 8/4-5 8/25-26 9/15-16 P, pectinatus 2.267 2.065 1.544 ' 2.508 2.265 1.919 1.839 1.748 1.114 Elodea 2.589 2.474 2.439 canadensis 2.760 2.476 2.398 2.767 2.507 2.491 Exclosures 1.690 0.477 1.756 1.398 1.322 1.204 1.279 0.602 1.462 others 1.845 1.724 1.887 2.137 1.591 2.100 1.839 1.556 2.134 P, pectinatus 2.215 1.602 1.556 2.004 1.301 0.954 1.857 1.634 0.301 Elodea 2.314 2.352 2.387 canadensis 2.444 2.167 1.763 2.831 2.692 2.600 Controls 2, foliosus 1.079 1.279 2.179 1.462 1.756 1.869 1.079 0.778 0.602 others 1.987 1.898 1.748 1.699 0.602 0.477 1.362 1.591 0.602 A = treatments = 2 (fixed) B = species = 4 (random) C = time = 3 (random) n = replications = 3 36 Figure 7a. Loglo Organic weight/time (Confid. Coef. 95%). Sago area Controls, 1964. —0.801 X l I 23.628 T I 7 .4 ‘ hr . i I? I L¢_ E4 .r— I I ' , I I/ I I II --40 days I I I/ ’ I / I . I I I‘ I I \ I I I / I I II I I III 430 I I III I (I, I III ' I l I /’;lr I II I 1— _LI I 1 CF I _ i ’ IT 4 I I r I F fl] I 4'20 / I I I | I I I I I I I m1 I :51 ‘° - ‘3I ,8 I H --110 o .4 [d H I .l I cull| I / I I I / I I ' v ‘ =1 . I I 1’. I I ' L E T7 “41— 1‘ I O 3 2 1 Log10 (Organic weight 10) 37 organic weight/time (confid. coef. 95%). Figure 7b. LOG10 Sago area exclosures, 1964 I: .i I 1 . PET—q \ f \ fl \ .40 days I \ / \ I / \ I \ \ I I I \l \ I y \ I /\ \ ~30 I I \ \ l / \ \ l. / \ \ | / \ II-—_I___I 1 . I—I ." I . 7 I I I I / I20 I I I / I I I I I gI I 01/ I I5! I 5’ m m (U .5, H, .3, 0] u w I, c 0 'SI 0/ 3! w' 23’ *4 mI I I a." ‘10 a", I 0' I I I , I I I / I I I I .J .I L/ . .1 '.T If 'J‘ I L ' v ' 4 I ll 1 j g 1 0 3 2 l 0 Log10 (Organic weight 10) 38 Table 5. Analysis of variance of the transformed exclosure data from the Sago sample area. W Degrees of Sums of Mean Source Freedom Squares Squares F A (fixed) 1 1.1628 1.1628 1.9739° XX B (random) 3 13.5060 4.5020 12.1939 c (random) 2 1.4913 0.7457 2.0198° AB 3 1.1095 0.3698 3.6578° AC 2 0.6407 0.3204 3.1691° BC 6 2.2152 0.3692 2.4845° ABC 6 0.6063 0.1011 0.6803° Error 48 7.1329 0.1486 Total 71 27.8647 0.3925 1Table of Estimated Mean Sums of Squares, Appendix II. 39 Table 6. Exclosure data for the CriSpus sample area° Y = organic weight in grams (550 C). Dates (C) Treatment (A) Species (B) 8/19.24 9/9-10 E, crispus 18.9 10.2 4.5 3.9 5.7 42.8 g, foliosus 14.4 16.7 1.4 6.9 6.7 22.0 Exclosures . Ceratophyllum 0.4 0.3 demersum. 0.3 ‘0.9 0 0.7 Heteranthera 0 T dubia 0 0 T 5.8 others 2.7 1.8 1.4 1.4 0.9 3.5 2, crispus 9.2 10.8 7.8 5.2 4.6 1.1 “g. foliosus 1.9 3.5 3.1 5.8 0.8 2,6 Controls - Ceratophyllum 1.1 0.9 demersum 0.1 0.5 2.0 8.4 Heteranthera 0.3 0 dubia O O 0 0 others 3.1 2.4 1.3 1.8 3.3 0.9 T = trace (less than 0.1 grams) 40 Table 7. Transformed exclosure data for the Crispus sample area. Y' = loglo(10Y) W Dates (C) Treatments (A) (Species (B) 8/19,24 9/9-10 2, crispus 2.277 2.009 1.653 1.591 1.756 2.631 g, foliosus 2.158 2.223 1.146 1.839 1.826 2.342 Exclosures Ceratophyllum 0.602 0.477 demersum 0.477 0.954 0 0.845 Heteranthera 0 T dubia 0 0 T 1.763 others 1.431 1.255 1.146 1.146 0.954 1.544 g, crisEus 1.964 2.033 1.892 1.716 1.663 1.041 g, foliosus 1.279 1.544 1.491 1.763 0.903 1.415 Controls CeratOphyllum 1.041 0.954 demersum 0.000 0.699 1.301 1.924 Heteranthera 0.477 ‘0 dubia 0 0 0 0 others 1.491 1.380 1.114 1.255 1.519 0.954 T calculated as 0. . A = treatments r= 2 (fixed) B = species = 5 (random) C = time ==2 (random) n = replications = 3 41 Figure 83. Log10 organic weight/time (Confid. Coef. 95%). Crispus area controlsI 1964.‘ 3 .— .1- 8 ._I ° 2 - _ ..I_ .) "I -1- p .1: h ‘ ‘0 cri .9 ~ ~\ei;&: - a) -- e 1 _ I 3 us ‘JHI o S ’ ’ .3 . 7- 9. W’ g5 II-n’ [Zn-.3“ to h I ’ 2 Get} , 7 8‘ (J: 7 .4 .- -_L Us __ _We_ra_ 0 - ‘ ~ ‘ ~ ~ "" t =I. 0 10 20 days 42 Figure 8b. Log10 organic weight/time (Confid. Coef. Log10 (Organic weight - 10) 93%). Crispus area exclosures, 1964. T- 3‘-1~ ill- I. 4'» 2 P“ 2.11—1‘9-‘5'1; .. [£61105 "r' If]? . ers __ —- "' l .V"' 1‘C’II I-Ib h I ’ . “' W , III -_ .z’ I ‘3 / I the / I W 39 ,, / / -- 0 g / l O 10 I days f‘ \D L w - (D AV. 43 Table 8. Analysis of variance of the transformed exclosure data from the Crispus sample area.1 W Degrees of Sums of Mean Source Freedom .Squares* Squares* F A (fixed) 1 0.174 0.174 0.2555° XX B (random) 4 22.050 5.513 41.1418 0 (random) 1 0.548 0.548 4.0896° AB 4 1.553 0.388 5.7059° AC 1 0.361 0.361 5.3088° BC 4 0.537 0.134 0.7701° ABC 4 0.271 0.068 0.39080 Error 40 6.977 0.174 Total 59 32.471 *This test was checked for only three decimal places. 1Table of Estimated Mean Sums of Squares, Appendix II. 44 Figure 9: Cladophora on Sago Exclosure #2, September 9, 1964. 45 Bottom samples: The organic weights of the various plant parts found in the bottom samples are shown in Table 9. Note that these samples represent three replications lumped together, i.e. three square meters. Table 10, shows the relative amount (percentage) of the total plant material Sampled which occurred in the bottom samples; in other words, sampling error. These figures show that the most important errors encountered in the plant samples involved reproductive structures in the form of Winter leaf buds of g, crispus and g, foliosus and the seeds of £3 pectinatus. This is not surprising as both the Winter leaf buds and seeds break away from the parent plant rather easily, are small and rather buoyant. This means that not only would they not be seen because of the turbidity but that they would not be encountered when one sifts through the mud for stems and roots. By allowing things to settle for a moment before gently feeling around on the bottom, many buds and seed heads were recovered that might have other- wise been overlooked. However, the sampling frame was only 12 inches high, and I suspect that many buds and seeds were able to float over its rim in the remaining 5 or 6 inches of water. It is worth noting that this 46 material would also be overlooked in the bottom samples. The relative amount of error (Table 10) is sur- prising. Physically, the amount of plant material appear- ing in the bottom samples is very small, but because the structures involved largely represent energy storage mechanisms, they become important in an organic weight determination. The increase in error over the season probably represents continued Winter bud and seed produc- tion with accelerating foliage destruction at the end of the growing season. The only other plant important to the error value is Elodea canadensis. This became very brittle and dif- ficult to sample late in the season. Earlier, as it was dying back, 2, pectinatus was also necrotic and brittle with measurable effect in the exclosures. 47 Table 9. Plant material in the bottom samples. organic weight in grams/3 m. t —T —— Sago Sample Area Material Exclosures Controls 8/5 9/15 8/4 9/16 ‘2. pectinatus foliage 10.8 0 1.1 0 seeds and tubers 10.8 6.5 15.1 51.8 g, crisEus 1.1 0 1.1 Elodea 1.1 58.3 1.1 34.6 g. foliosus 2.2 8.6 2.2 8.6 Heteranthera 0 8.6 0 Total 26.0 82.0 20.6 95.0 Crispus Sample Area Material Exclosures Controls 8/24 9/10 8/19 f9/9 .2. crispus foliage 0 0 0 8.6 seeds and buds 21.6 51.8 30.2 34.6 3, foliosus 2.2 19.4 1.1 21.6 .E. pectinatus (seeds) 1.1 0 2.2 4.3 Ceratophyllum 0 8.6 0 1.1 Elodea 0 1.1 0 0 Heteranthera 0 1.1 0 0 Total 24.9 82.0 33.5 50.8 48 Table 10. Sampling error (grams organic weight/3mg). m Controls Exclosures Sago Sample Area 8/5 9/15 8/4 9/16 Total Plant Samples 249.3 140.7 172.2 103.9 Total Bottom Samples .0 82.0 20.6 95.0 Total 275.3 222.7 192.8 198.9 % in Bottom Samples 9 . 5% 36 . 1% 10 . 7% 47 .7% m w ExcloSures Controls Crispus Sample Area 8/24 9/10 8/19 9/9 Total Plant Samples 57.4 117.0 38.6 43.9 Total Bottom Samples 24.9 82.0 33.5 50.8 Total 82.3 199.0 72.1 94.7 % in Bottom Samples 30.1% 41.2% 46.4% 53.7% W 49 Analysis of the depth data: The primary purpose of the depth data was to confirm, in my sample areas, the evidence that carp tend to excavate areas they use and fill-in adjacent areas in which they are not active. King reported up to three inches difference between exclosures and con- trols in several of his sample areas (1965:46, Table 3). Figure 9 (0p. cit., p. 30) of his thesis is a photograph of both an exclosure and control area completely filled up by carp activity. How this effect may come about is discussed in detail in Chapter VI. Because the effect Of carp on depth seemed to be a good indicator of their presence, the sounding data served a second purpose. By comparing the depth of the controls to the depths of the areas bordering the samples, it is possible to detect any changes in the controls which would indirectly indicate an increased or decreased utili- zation by carp. The previously mentioned Figure 9 in King's thesis suggests that in clear water, anyway, carp are wary of stakes and avoid control areas. King points out that this wariness disappears in turbid water (0p. cit., p. 29). However, I felt it worthwhile to check the controls in this manner to be sure that the combination of stakes and path around the control areas did not affect 50 activity of carp inside. Thus, a 3-way analysis of variance was made on the depth data (Figure 10) to test 1) the hypothesis that the exclosures filled up somewhat, and 2) the hypothesis that the controls remained at the same level as the out— side areas.' In order to test these specific hypotheses, it was necessary to make individual degree of freedom computations following the test for treatment mean heterogeneity. Although soundings were made in the areas between the exclosures and control areas, these data were thrown out, a_priori, as the bottom had been disturbed during the installation of the exclosures. Treatments (A) consist of exclosures (A1)' controls (A2), outside east (A3), and outside west (A4). There are three sets of samples (B) in each of the two plant provinces (C). The replications consist of two observations taken two meters apart as shown in Figure 8. Assumptions of variance homogeneity and independence of means and variances were tested and accepted. The data conforms to a mixed model. The treatment (A) and plant provinces (C) represent fixed components of variance, while the sample component of variance (B) is 51 random. Thus, the estimated mean square for treatment is made up of error effect, treatment effect, and 1st and 92nd order interaction with the random variable (B). Similarly, the other fixed component of variance (C) is made up of error, plant province effect, plus lst and 2nd order interaction involving (B) and (C). 0n the other hand, the estimated mean square for samples (B), the ran- dom component, consists of error effect and sample effect, only. This is because components (A) and (B) are constant, and any variation within the samples of a given treatment in a given province can only be caused by random effects. This is summarized in the table of estimated mean sums of squares (EMSS), Appendix III. The null hypothesis of treatment mean homogeneity is rejected at the 5% level but accepted at the L% level. The Specific hypothesis that the mean exclosure depth is the same as the average of the means of the other treat— ments, tested by an individual degree of freedom computa- tion, is rejected at the 1%M1evel. The second specific hypothesis that the mean depth of the controls is the same as the mean depths outside the sample areas, used to find evidence of deferential use by carp, is accepted at the 5%.level and suggests that the treatment mean homo- 52 geneity is confined to the exclosure means. The analysis of variance also suggests that the mean depths of the two plant provinces are different. At most this implies a certain amount of universality for the carp effect. The 2nd order interaction, which is significant at the 5%.1evel, probably carries over from the very significant difference between plant provinces. When the data is plotted (Figure 11) it becomes apparent that the outside depths on the west side of the~ Crispus province are shallower than eXpected. This appears as treatment-province interaction, but is not significant at 5% level. I interpret this as resulting from the shelving of the bottom toward shore. One would eXpect this on the west side of the bay as it represents the original shoreline of Lake Erie. The east side of the bay is a recent (1953) dike. Although the first specific hypothesis, that the exclosures are at the same level as the rest of the area tested is significant, my observations of the vegetation in the sample area lead me to believe that the carp did not reach the Sago area, at least, until very late in August. These observations are supported by the results 53 of the exclosure study which suggested that carp did not affect the vegetation. Consequently, I attribute the fil- ling effect to carp activity between late August and September 8th when the depth data were collected. Due to the relatively Sparse vegetation at the Crispus area the effects of carp upon the vegetation were not so easily determined. Possibly carp were present in the Crispus area over a longer period, although their effect upon the bottom there does not appear to be significantly greater than the Sago area (Figure 11). Observations by King (1965:46, Table 3) tend to support the idea that carp did not penetrate the large areas of pondweed in North Bay until late in the season in 1964. He reported no filling in at his area #5 (organic soil) in the northeastern corner of North Bay in the approximately 10 weeks between May 18th and August lst. My exclosures (marl) filled in approximately one inch in about six weeks between the end of July and September 9th. King stated that in 1965 sample #5', in the same area, filled in 1 1/2 inches between May 28th and August 1st. This suggests that the carp may have reached my sample areas in the same year and produced significant amounts of turnover. 54 Figure 10. Depth data from the sample areas. Y = inches. Sago Sample Area (Cl) 17.50 18.00 19.50 18.25 18.25 17.25 r—--_-I r-___'7 I18.00 18.00 I18.25* 17.00 16.50 18.25* I18.00 17.25! _____ _I L... _.._ - _J 17.50! 17.50* (B3) 18.25* 17.50* (82) 18.25* 17.50*(8£ I—-----I 17.25 17.75 l7.75*l 18.00 l7-50|l8.25* 17.25 16.50 I.___...__l 18.00 18.00 17.50 18.00 19.00 16.50 E N 4 I s Crispus Sample Area (C2) W 16.25 17.00 17.00 16.50 16.25 17.25 r—----I I—-—--_| |l7.50 17.25: 16.75* 16.00 16.00 16.75*, 17.75 17.00, u---_4 L-__-4 17.00* 16.75* (B6) 16.25* 17.25* (B5) 17.00* 16.75*(8Q l”_b-‘j 15.25 15.25 16.00*| 16.25 16.00I16.50* 16.50 15.50 L______J 16.25 16.00 16.25 15.75 16.50 15.00 *Not used in analysis of variance. msoflumoflamon moocfl>onm AEOUCMHV mucmaumwuu II ‘EIDUG moamamm 55 oo.oH oo.eH m~.aH m~.ma mm.oa om.oH om.as m~.ma ma.ma om.oa oo.oH oo.oH m~.oH oo.aH m~.oa oo.oH mon< noonano oo.mH m~.ea oo.eH om.me om.oH m~.oH mo.aa om.oH om.mH oo.mH oo.ma me.aa oo.mH om.eH oo.mH m~.ea oo.mH m~.ms om.aa om.oa om.aa om.ma oo.mH oo.eH monm comm om.mH m~.oa m~.aa om.oa oo.mH m~.mH oo.mH m~.na 3 GUHmHDO @UHmHDO mHOHuGOU meSmOHUXm Amy mHmEmm QUCH>OHQ 4.4 m4 9 5 A8 0863 .mm£UCH CH spawn .mocmaum> mo mamaamcm 05» GH poms numb gamma .HH magma 56 Table 12. Analysis of variance of the depth datal. M __—1- Degrees of Sums of Mean Source Freedom Squares Squares F A (fixed) 3 8.2018 2.7339 7.2982X B (random) 2 0.1484 0.0742 0.3183° 0 (fixed) 1 25.1575 25.1575 288.1730XX AB 6 2.2474 0.3749 1.60700 AC 3 3.3581 1.1194 1.7275° BC 2 0.1745 0.0873 0.3745° ABC 6 3.8881 0.6480 2.7799x Error 24 5.5937 0.2331 Total 47 48.7695 Tests of Specific Hypotheses: (Individual degrees of freedom) 1. H : u = “controls + U outside E + u outside W o exclosures 3 2 F 0 7 4529 xx V —— _;_..___ AB 2. H : u = u outside E + u outside W 0 controls 2 F - 02 - 0 0854 - 0 V r O — (1. ) ';—— 073726' 0.2280 AB 1Table of Estimated Mean Sums of Squares, Appendix III. 57 Figure 11. Depth Data: Mean of replications/samples. Y = inches. 19.00- 18.00 11 Controls (Treatment A2) 17.00 a K Outside E (Treatment A3) NI Outside W (Treatment A4) 16.00-J Exclosures (Treatment Al) 15.00 - Sago Crispus (c1) (c2) 58 The productivity study: Primary productivity estimates cal- culated from standing crop measurements have been made for many areas and have appeared frequently in the literature. Although this method of determining productivity has been justifiably criticized (wetzel, 1964:24-27, 38—29), the results of such calculations for Erie Marsh would represent a useful index with which comparisons between the marsh and other aquatic systems could be made. For this reason plant samples were taken at both sample areas at the very beginning of the growing season in 1965 (May lst) and again at peak standing crOp (July 4th). The increments in organic weight and dry weight over this period were divided by the number of days in the interval (64) to pro- duce the rate estimates. Before the results of these calculations can be discussed and accurately interpreted, several assumptions inherent in the method must be understood. Possibly the most sensitive assumption made in this type of productivity estimate involves the presence of turnover. Turnover is the rate at which biomass is cropped off or otherwise re- moved from the area of production. Significant turnover rates result in depressed biomass measurements and, con- sequently, under estimates of productivity. 59 As previously mentioned in the exclosure study, the lack of Significance between protected and unprotected vegetation indicates that little or no turnover occurred at the sample areas during the sample period in 1964. In 1965, however, when the productivity samples were taken, King (1965:57) stated that the effect of carp was greater. Also, the productivity study was made during the first half of the growing season, and King (Op. cit., p. 67) suggested that carp have a much greater effect upon young plants. The analysis of the depth data, taken in 1964, indicates that carp probably did enter the sample areas that year, although apparently not in sufficient numbers to affect the plants. As previously mentioned, King's depth data for his sample #5 (1964), which was in north- eastern North Bay, was negative during the early part of the season (through July), but positive for approximately the same period in 1965 (sample #5'). His plant data for both samples #5 and #5' were significant, but #5' (1965) was more so. Consequently, there is evidence that the carp arrived earlier at the pondweed areas in North Bay in 1965 than in 1964. My observations of the vegetation on July 4th in 1965 lead me to believe that carp were in 60 area, however the vegetation was less disturbed by them than it was in September, 1964, when the exclosures still failed to show significance. I think it is safe to say in conclusion, that carp—caused turnover was not very im- portant in the 1965 samples. Other effects of carp are discussed in Chapter VI. I Because of the large interval (64 days) between the two 1965 samples, another.assumption is probably in- valid for the productivity calculations. Because of limited time, I had to guess when the growing season started and when the vegetation peaked and confine my sampling to these two periods. Although I do think I was able to estimate these points well from having already had a year's experience in the marsh, I cannot be sure, but more important, I have no idea of the shape of the standing crOp curve. The calCulations assume linearity, so I must limit my conclusions to average productivity over the sample period and carefully avoid any allusion to terms which imply instantaneous rates. A third assumption concerns sampling error. Material overlooked during sampling systematically lowers the productivity curve. The bottom samples (1964) show that plant sampling error became very important as the 61 growing season progressed and more reproductive, energy storing structures were produCed. The 1965 plant samples however, were taken early in the season, before the vari- ous reproductive structures matured. Therefore, I feel that sampling error is negligible in the productivity study. Analysis of the productiVity data: Productivity is cal- culated in Table 15. Note that I ignored Elodea in the computation of the Sago sample area figures because this species decreased during the sample period (Figure 12). Because of the assumptions previously described, these figures are undoubtably underestimates. Turnover probably occurred even if carp were absent. Waterfowl, other fish Species (Chapter IV), and invertebrates (Chapter V) are known to be present in the area. Growth probably did not start exactly on May lst, and photosyn- thesis certainly did not cease abruptly on July 4th. Figures 7 and 8 show that several species continued to grow late in the 1964 season. Furthermore, the aquatic macrOphytes are not the only means of photosynthesis. Periphyton, and photosynthetic bacteria probably add significant amounts to the community. PhytOplankton may also be important in spite of the severe turbidity. 62 This is probably particularly true when the marsh is frozen over and the turbidity disappears. Sampling error also affects the productivity esti- mates, but the direction is not clear. The sampling error derived from the bottom sample data is not the only type of sampling error. The large variance inherent in the sample from both areas in both years suggests a large amount of clumping in the vegetation, both by Species and in the absolute amount of vegetation present. The con- fidence intervals shown in Figures 7 and 8 (1964) and 12 and 13 (1965 (computed together) are still quite large in- spite of the log transformation. Confidence intervals for the raw data were invariably twice as large as the means. Thus, as Figures 12 and 13 indicate, very little precision can be expected from these data. As is frequently the case, twice as many samples, twice as large, should have been taken twice as often in this study. Unfortunately, this wOuld have required twice as many workers. Comparisons of productivity data: Recently, Westlake (1963) reviewed and summarized the productivity figures which have appeared in the literature. Using metric tons of organic production/hectare/year as units. he compared many terrestrial and aquatic communities. Converting the 63 organic weight data from the July 4th maximum (0.01 times grams/meter2 = m. t./ha.), produces values of 1.1 and 0.5 m. t./ha. for the Sago and Crispus areas, respectively. This places the sample areas at Erie Marsh at the lower end of the range for submerged angiosperms at infertile sites (1.0 - 2.5 m. t./ha./yr.) according to Westlake. It must be pointed out, however, that my figures represent underestimates (see above), particularly with respect to phytoplankton productivity which Westlake accounted for and I ignored. For comparison, it is interesting to note that~ Westlake estimated production of submerged aquatic plants at temperate, fertile sites between 4 and 7 m. t./ha./hr. Temperate, shallow, benthic, marine plant production (25 - 33 m. t./ha./yr.) and fertile reed swamps (30 - 45 m. t./ ha./yr.) are much higher. Figures for temperate, fertile, terrestial sites include: coniferous forests, perennial herbs, and intensive agriculture at 25 - 40 m. t./ha-/hr. and deciduous forests, uncultivated herbs, and cultivated annuals at 10 - 25 m. t./ha./hr. Seed and Winter leaf bud production: Table 16 was drawn up from both the plant data and the bottom sample data, where noted. The plant data represent the mean of 3 one 64 square meter replications. The bottom sample replications were exPanded by a factor from 2 thirty-six square inch Eckman dredge samples to be equivalent to a square meter replication. 3, foliosus Winter leaf buds, which were present in most samples in large numbers, are not included. They are so small and so similar to the foliage that no effec- tive method could be devised to isolate them. 2, RES: tinatus produced both seeds and tubers, but I saw less than a dozen tubers during all the sampling Operations in the marsh. Those which I did find occurred mostly in the Sago area on July 4th, 1965. g, crispus produced both seeds and Winter leaf buds in large numbers. The Winter leaf buds are much more important in these figures due to their large size. 65 Table 13a. Productivity data for the Sago sample area. ' Y = organic weight in grams (550 C) W Treatment Species Dates 5/1/65 7/4/65 .3- pectinatus T 150.3 - 0 54.9 0 103.7 Elodea 7.6 2.0 Controls canadensis 6.2 3.9 20.3 2.0 P. foliosus 0 0.9 0 1.8 0 7.2 others T 0.5 T 0.6 TT 2.6 Table 13b. Transformed productivity data for the Sago sample area. Y' = loglo(10Y) W Treatment Species Dates 5/1/65 7/4/65 'g. pectinatus T 3.177 0 2.740 0 3.016 Elodea 1.881 1.301 Controls canadensis 1.792 1.591 2.308 1.301 P, foliosus 0 0.954 0 1.255 0 1.857 others T 0.699 T 0.778 TT 1.415 66 Figure 12. Log10 organic weight/time (Confid. Coe. 95%). Sago area, 1965 4— 3_ I ,/ A I o / H II 0 III /// 4.) -— 6 2’ w-l / (D / 3 x / .U 2 __ ‘ Elode / m. ; I‘ f:‘::3 // f0" ‘ ~ \ / a" - ~ 1 / O /’ ‘ \ \ V ’4 ~ ‘ ‘ / ~ ~ 2 / / .I. / ./ §‘ ./ //” .L I 0 10 20 30 40 50 60 days 67 Table 14a. Productivity data for the CriSpus sample area. Y = organic weight in grams (550 C) *‘E: . r Treatment Species Dates 5/1/65 7/4/65 3, crispus 0 6.6 0.4 27.5 . 0.2 32.0 g, foliosus 0 9.8 0 10.3 0 15.3 Controls 2, pectinatus 0 14.4 0 13.6 0 9.6 others TT 0.4 T 0.1 TTT 0 Table 14b. Transformed productivity data for the CriSpus area. Y' = loglo(lOY) Treatment Species Dates 5/1/65 7/4/65 2, crisEus 0 1.820 0.602 2.439 0.301 2.505 '2. foliosus 0 1.991 0 2.013 0 2.185 Controls 2, pectinatus 0 2.158 0 2.134 0 1.982 others T 0.602 T 0.000 T 0 Figure 13. ) Loglo (Organic weight - 68 Log10 organic weight/time (Confid. Coef. 95%). Crispus area, 1965. 69 Table 15. Productivity calculations for 1965 samples. W Dry Weight/m? Organic Weight/mg * * Item Sago Crispus Sago Crispus 5/1/65 0.3 g 0.7 g 0.1 g 0.3 g 7/4/65 176.7 g 73.6 g 107.5 g 46.5 g Biomass (64 days) 176.4 g 72.9 107.4 g 46.2 g 2 Grams/m./day 2.8 1.1 1.7 0.7 Annual gms./m%/day 0.5 0.2 0.3 0.1 (365 days) *Elodea in the Sago area decreased during the sample period and was ignored in the computations. 70 Table 16. Seed and Winter leaf bud productionl. Y = organic weight/m. (means of 3 replications) _— a m Sago Sample Area 5/1/65 7/4/65 8/5/642 9/15/642 Exclosures: ‘g. pectinatus (seeds) - - 5.3 2.6 E. crispus (seeds and '“Winter buds) ’ - - 0.4 0 5/1/65 7/4/65 8/4/642 9/16/642 Controls: E, pectinatus (seeds) 0 0.9 6.2 18.1 ‘3. crispus (seeds and Winter buds) 0 0 0.4 _ CriSpus Sample Area 5/1/65 7/4/65 8/24/642 9/10/642 Exclosures: '3. pectinatus (seeds) - - 0.4 0 .E- crispus (seeds and Winter buds) - - 11.2 22.4 5/1/65 7/4/65 8/19/642 9/9/642 Controls: .2. pectinatus (seeds) 0 0.3 0.8 1.4 g. crispus (seeds and Winter buds) 0 0.3 2.0 12.7 12, foliosus not included. 2Sum of plant and bottom samples. IV. FISH IN THE SAGO SAMPLE AREA In order to obtain an estimate of the fish popu- lation actually surrounding the sample areas, a small area, approximately 25 yards in diameter, near the sago sample was treated with rotenone on September 9, 1964 (3:00 PM). (See Figure 1.) Mr. Kenneth Reau, the club manager, offered the use of the rotenone for which I am very grateful. The chemical had been eXposed to the elements for several years and had obviously deteriorated to some extent. It is not known, therefore, if the minimum toxicity for total kill was achieved. Six ll quart pails of the dry material were mixed into a slurry, then poured into the wake of the boat. My strategy con- sisted of making a large ring initially, then blanketing the enclosed area. The effects were immediate. Gizzard shad came up first, followed by everything else. The bullheads came up last and seemed to be the most resistant to the chemi— cal. Besides the possibility of less than 100%»kill, another possible bias entered the sample when I had to 71 72 compete with a flock of seagulls to pick up the paralyzed fish. The results of the poisoning are tabulated in Table 17. Young carp are the most frequently encountered fish, with black bullheads a close second. Green sunfish are also common; goldfish and gizzard shad less so. Giz- ard shad are the largest fish in the sample, and they may approach dominant biomass in the sample area on that basis. If minimum toxicity was not achieved, the appar- ent susceptability of the shad may have biased the sample in their favor. No adult carp were captured. They were seen in other parts of the bay at the time, but they may have had enough stamina to escape the small lethal area, if any entered it at all. Sampling was also attempted with a small, commer- cially produced minnow trap and with a homemade trap of greater pr0portions supplied by Mr. Reau. In all cases, sunfish were very dominant in these samples, and, if the poisoning results are accurate, represent a tremendous bias in favor of sunfish by the trapping technique. In addition to these observations made at the sampling site, I caught and saw fish caught at other loca- tions. Several white bass, all about 4 inches long, were 73 caught in South Bay, and club members' children enjoyed great success at the BoathouSe Dock catching bullheads and bluegills. Previous investigators in the marsh have found in addition, yellow perch, black crappie, smallmouth black bass, dogfish, walleye, and gar (Hunt, 1958:37); channel catfish and yellow bullheads (Tack and Singh, 1959:2); ”shiners" (Matulis and Pirnie, l960:7). The poorly screened weir connecting the marsh to Lake Erie makes it possible for any species in western Lake Erie to enter the bays. AS Table 17 indicates, many of the fish in the area could go through the one inch netting of the exclo- sures. These are probably the only vertebrates that entered the exclosures. The small size and high sides of the exclosures would discourage waterfowl. 74 nmoa .soom noosmnommm mHH OH ma OH mm mm HvaB A.mmmv mQOmNHQU msooom mmmn mumfiK Ausmsmoqv adamaoflmoo mfiOmOHoa pmnm pHmNNHw A.sGHAv mamonnwm mflfiommq pommcfixmadm A.csfiqv mSmOQQHm mHEomoA Smflmssm wauo A.ssflqv mouoHSmImsHmmmnmo. Smflmfiaow A.scflqv oamumo msaflnmmu ammo Annmsquv mdmoasnos mSHsHmuoH pmmnaasn s3osm A.mmmv mmaofi mSHSHTuOH pmmnaasn xomam Hopes NHIOH Calm mlm oto film Nlo Awsocwuonv soma .m HTQEoummm "poc0mflom A.£umcwa Unmpcmum mumumEHuswo.cH momwmao mummy .voma mo “meadm map manusp cmxmu I mono onEmm 00mm on“ How: £mwm .ba magma 75 mm . Hmuoe v H m H.mmmv msHHocmmu mHeome gmHmcsm combo H H H.csHHv Odmumo mssHummo mumo :N x H smoE .rm mcHsomo oHIm nwssmummm .~\H H x .m x .~\H m dons men h o H N H.GGHHV mSmOQQHm mHEommH tomemeesm om H mm m m H.mmmv mDHHmcmmu mHEomoH anMCST somuo m N H.GGHHV onmoU mscHHQNU mumu H H A.mmmv mmuoE mausHmauH GMOHHHSQ MumHm :¢\H SmoE .sH mchmmo .MHp =m x shH mmuu 3oscHS Hmuoa 01o «IN mlo , old sum ¢HIOH Honsmumwm mum Honfioumom Ummmmua H.u.coov H.£umcwH tnmncmum wumuwfiflucmo CH mommmHO mNHmv .vomH mo Hmfifidm mnu mcHHso smxmu Imwhm meEmm ommm may Hmmc QmHm .hH mHQmB V. INVERTEBRATES IN THE SAMPLE AREAS1 Invertebrates were not systematically collected during this study. Many midge larvae (Tendipides) were found in the bottom samples, but, because these samples were taken immediately after the plants were removed from the same area with the resulting disturbance of the bottom, the samples are not quantitative. Snails were not common in the vegetation, although there were large numbers of empty shell in the bottom material. Amphipods occurred frequently in the plant samples but not in large numbers. One crayfish [Orconectes immunis (Hagen)] was found in a minnow trap, and five more were captured during the re- moval of the exclosures. One freshwater clam [Anodonta marginata (Say)] was found in the Sago area. Leechs [Placobdells parasitica (Say)] were frequently seen during the installation of the exclosures. Several damsel fly casts were found on exclosure and control stakes in 1964. As I will describe later (Chapter VI), piscicides lReference: Eddy and Hodson, 1962 76 77 have been frequently used in the marsh. Tack and Singh (1959) demonstrated the slow recovery of midges (Tendipides) from the 1958 poisoning. Crayfish were also affected. Backswimmers (Notonectidae) and water boatmen (Corixidae) were wiped out in poisoned areas in 1962 and recovered only slightly in 1963 (Foster, l962:3 and l963:6). Dr. Hunt (1958:39-40) experimented with 3 Species of snails in 1958 and stated that they have an immunity to toxaphene. In 1962 living snails were observed following the poison- ing that year (Pirnie and Foster, 1964:28). VI. CARP AND TURBIDITY The effects of carp are a traditional problem in Erie Marsh. Recently, King (1965) dealt with the effects of carp upon the aquatic vegetation specifically. His evidence concerning the direct effects of carp, i.e. those which may be differentiated between exclosed and unpro- tected areas, have already been discussed with respect to my sample areas. The indirect effects of carp upon the marsh, i.e. turbidity and silting, are much more dif- ficult to measure, and neither Mr. King nor I were able to find good evidence concerning this problem. Mr. King, consequently, confined his discussion almost entirely to the direct effects of carp and made only brief mention of the possible indirect effects. The dry and organic weight biomass and produc- tivity data discussed in the productivity study are probably the best evidence available concerning the possi- ble detrimental indirect effects of carp upon the vegetation in the marsh. Yet, comparisons drawn between the sample areas at the marsh and other areas described in the litera- 78 79 ture do not account for the many other environmental factors, unique to an area, which are known to affect plant growth. In addition, I have become aware, both by personal observation and from the literature, of cer— tain phenomena which raise the possibility of significant indirect effects of carp upon aquatic vegetation. Conse- quently, I would like to supplement Mr. King's topic with a critical review of his discussion of carp and turbidity, as well as other literature, in light of my own observa- tions. Eggp: Carp are always present in the marsh despite four recent attempts to poison them out. Toxaphene was applied on July 17, 1958 (Tack and Singh, l959:1); June 2 and 5, 1959 (Hunt, 1959:22); July 26, 1962 (Pirnie and Foster, 1964:24), and an application of rotenone was made sometime between 1953 and 1957 (King, 1965:17). Following every poisoning, large numbers of carp were again evident in the marsh within a few months (Hunt, 1958:39, 1959:22-24, and Matulis and Pirnie, l960:7), and there is some doubt that 100% kill was achieved at any time. Apparently the weir which connects the marsh to Lake Erie is a source of carp reinfestation. Foster (l962:5) reported that two addi- tional poisonings in the immediate vicinity of the weir, 80 following the main poisoning Operation by about a month, killed a few large carp and up to 500 small ones. In the early Spring of 1964 and several times in the Winter of 1964-65, I observed hundreds of young and adult carp lin- ing up on the Lake Erie side of the weir. King (1965:30, Figure 8) has an excellent picture of this lining up behavior in the marsh. (In that case the carp were attempting to enter the Sulfur Springs outlet.) A screen, capable of preventing larger carp from passing through the weir (Pirnie and Foster, 1964:26), was removed on July 28, 1964. .Carp are the most commonly observed fish in the marsh, and large numbers of adults could be seen anytime one walked the edge of a canal or dike in 1964 and 1965. In North Bay adults were always evident in one area or another during my sampling trips. Reports to the Erie Committee indicate how dominant and numerous the carp are in the marsh. In 1959, Tack and Singh (l959:2) reported that 95% of the fish (by numbers) poisoned the previous Summer were carp between one and six pounds. They also reported that 4.5% of the kill consisted of goldfish X carp hybrids. In 1962, Wood (l962:1) estimated the kill that year was on the order of 100,000 pounds of fish, of 81 which 99% were carp. King (1965:40) estimated carp den- sity in North Bay on June 22, 1965 at 100 to 200 individuals per acre, or 500-1000 pounds per acre. Turbidity: Turbidity was a constant feature in North Bay during 1964 and 1965, with the exception of periods with ice cover. In the sample area, I seldom recorded secchi disk readings of more than a foot. King (1965:65) stated that average secchi disk readings for any of his locations were never more than 4 1/2 inches less than the depth. Concurrent with the turbidity was a great deal of silt deposition on the aquatic vegetation. The Erie Reports since 1957 mention turbidity and silting of the vegetation repeatedly. The evidence concerning the turbidity in Erie Marsh recorded to date poses two perplexing questions whose answers each involve a paradox. First, what causes the observed turbidity? Paradoxically, the water is turbid and the vegetation silted even in the middle of solid, apparently undisturbed vegetation. Second, does the tur- bidity affect the plants? On the other hand, there are vast areas in the marsh which support extremely dense veg- etation:hispite of the turbidity and silt deposition which could drastically reduce the energy available for photo- 82 synthesis. The cause of turbidity: The traditional assumption is that the direct cause of turbidity at the marsh is sus- pended bottom material, and that the roiling produced by feeding carp is the agency which puts the bottom material into suspension. The silt on the vegetation results from the bottom material coming out of suspension. There is good evidence for this mechanism. First, there are direct observations of the feed- ing behavior of carp (King, 1965:40, and Black, 1946) which indicate that the carp seek food in the bottom material. These observations are by the strong evidence that carp affect the bottom relief in the marsh. King (Op. cit., p. 40-41) reported that on several occassions he investigated areas where carp had been feeding, and each time he found depressions in the bottom which were devoid of vegetation. In July of 1965, in the northern part of North Bay (an area supporting sago and other pond- weeds), he discovered holes in the bottom one to four feet wide and two to six inches deep. He estimated that in an area heavily used by carp that five to ten percent of the bottom area had been directly disturbed by carp activity. Flats eXposed during the record low water of 1964 83 in Lake Erie, on the other side of the South Dike, gave additional evidence of what the bottom of North Bay may look like. The flats were pitted in a manner which sug- gested the work of feeding carp. The pits tended to be elongate, with one side abrupt and the other s10ping. The pits were generally less than‘four inches deep. As opposed to the five to ten percent area which King found in North Bay, I estimate that the pitting on the flats approached 50%»in some locations. Finally, the large variance in the sounding data from my sample areas sug- gested the presence of a great deal of irregularity on the bottom which probably reflected a pitted or wrinkled sur- face. Second, that carp haVe the ability to move a sig- nificant amount of bottom material in a limited time is suggested by the filling in of exclosures recorded by both King (1965:46, Table 3) and I (See: Analysis of the depth data). Third, the several poisonings of the marsh have produced eXperimental evidence, as opposed to strictly empirical, of the connection between carp and turbidity. Hunt (1958:23) reported that the turbidity and deposition of silt on the leaves ofIaquatic plants, all but disap- 84 peared following the 1958 poisoning. Secchi disk depths increased from 13 inches befOre the poisoning to 46 in- ches only five days after the 1959 poisoning (Hunt, 1959: 24). Foster (l962:3) and Wood (1962:2) again observed a clearing of the water and a disappearance of silt on the vegetation following a poisoning in 1962. Fourth, if the turbidity in the marsh is due to the presence of phytoplankton or zooplankton, one would eXpect the turbidity to remain unchanged following a poisoning or even to increase as a result of the nutrients released by the decomposing fish. Following the 1962 poi- soning, zooplankton did become noticeable, but not until a dramatic increase in water transparency had already occur- red (Wood, l962:2). Furthermore, it would be difficult to explain the tremendous amount of silt deposited on the vegetation if the turbidity was not caused by suspended bottom material. Fifth, the possibility that wind may stir up the bottom during mid-season is discredited by the rapid and dramatic clearing following carp removal. Hunt (1958:23) specifically mentions that winds of 20-25 MPH did not pro- duce turbidity following the poisoning of 1958. If the feeding activities of carp are the only 85 significant cause of turbidity in the marsh, the question remains as to why even large areas of very dense aquatic vegetation are turbid and silted when there is no evidence of physical penetration by carp. This paradox was particu- larly striking during July and August of 1964 at the Sago sample area. At the time the vegetation of the vast southern part of North Bay was very dense, and obviously had not yet been used by the carp. In spite of this, the vegetation had thick deposits of silt and the water that could be seen was turbid. It was not possible to take meaningful secchi disk readings during the period of very abundant vegetation because when the disk was forced through the vegetation, which grew right to the surface, the silt on the leaves became dislodged and immediately obscured the disk. Just previous to this period, between June 15 and July 2, King observed that the water was relatively clear (personal communication). This relatively clear period was during the very peak of vegetation that year, and this observation led King to conclude that the turbidity was more closely related to wind and bottom type early and late in the season (1965:95)° He felt that the turbidity present during mid—season, while the vegetation was up, 86 was caused by carp, but that this turbidity was not impor- tant (1965:65). According to King, then, the turbidity I observed between July and August, i.e. after die back, was caused by wind not carp. I cannot entirely agree with this conclusion. In spite of the dying back of the vegetation from the surface of the water, there was still a dense, re- silient layer of Eloden, encountered at a depth of 4-5 inches and continuing to the bottom present in the Sago sample area. Also, this dense but submerged vegetation showed not evidence of carp activity in the Sago area and the exclosures were not statistically significant. Carp were present in the bay but seemed to be limited to the west side. King (1965:41-42) observed heavy carp activity in the northwest corner of the bay, but stated that in 1964, at least, the carp tended to remain localized and in areas of less dense vegetation. By late August, carp did invade the Sago area as evidenced by the depth data taken in September. The results from the exclosure study indicate, however, that at no time was the effect of carp very great in the sample areas. If the turbidity produced by the carp is so long lasting that it is able to circulate from the limited areas of carp activity in North Bay in 1964 to the middle of my 87 eastern, Sago sample area, then the question remains as to why the marsh clears so quickly following a poisoning. One possible explanation for this is that clay, which can remain in colloidal susPension for long periods of time, is causing the turbidity and that some subtle change in water chemistry precipitates the colloid‘following a poisoning. Irwin and Stevenson (1951) have shown that any factor which liberates positive ions can produce a rapid flocculation and precip- itation of clay turbidity. Although the marsh contains a good stand of higher aquatics which probably produce an excess of flocculating agents (Irwin, 1945), I had a mechanical soil analysis run on one bottom sample from each sample area to determine the presence of clay in the marsh. The analysis was done by the Soil Testing Laboratory at Michigan State Univer- sity. Although the results are variable and made it necessary for the Soil Testing Laboratory to make two independent tests on each sample plus an additional one on the Sago sample, the clay determination was always less than ten percent averages approximately 5% in both areas. Of this 5%, possibly only a small fraction is true clay material; the rest Simply being very small silt particles. By far the dominant material in the samples was silt which 88 approximated 80% in both samples. The sand component represents small snail shells and other shell fragments as well as true sand. 'These results, according to Mr. Don Christianson (personal communication) presently in charge of the Soil Testing Laboratory, represent a situa- tion common to marl deposits,‘and are thus in accord with Eby's description of the area“(l959:13). Investigating the standard soil testing techniques used on these samples, led me to believe that the physical properties of the bottom material, at least in the sample areas, may not be in the marsh. A mechanical analysis of soil by the hydrometer (Bouyoucos) method is based on Stokes' Law which states, in effect, that particles fall through a liquid at a rate directly prOportional to the square of their radii. To perform a mechanical analysis, a given amount of soil is shaken up in a given amount of water, 40 seconds allowed for the sand to settle out, and then the density of the solution is measured. Two hours later the density is again measured, and the difference computed to determine the percentage of silt (USDA system), i.e. particles between 0.05 mm. and 0.002 mm. in diameter, which has settled out (Miller, Turk, and Foth, 1965:28-29). Thus the sample areas in North Bay, which are only a few 89 inches deeper than the standard 1000 ml. cylinder used in the soil test, should clear within about two hours in the absence of carp. As pointed out above, this does not seem to be the case for the Sago sample during July and August, although King recorded relatively clear water in North Bay earlier in the season. If the carp were absent during July and August from the Sago sample area as the vegetation seems to indicate by both visual observation and statistical analysis, then there must have been a very active circula- tion of suspended sediments from the area of carp activity in the northwestern corner of North Bay to the Sago sample area in the southeastern corner. How this circulation could occur in such dense vegetation is yet another para— dox. Possibly the wind, which prevails in roughly the right direction, can cause enough movement of the thin layer of water over the vegetation to tranSport at least the smaller particle turbidity the required distances. I observed that the turbidity resulting from sampling activ- ities moved down wind rapidly in the sample areas. In the absence of any real evidence that such cir- culation exists, at least two areas seem worthy of more investigation. First, an examination of the bottom 90 material under ice cover is in order. Possibly the low percentage of clay present in the Summer when the area is turbid means that most of the clay present is already in suSpension in the water. This could also be checked with samples of turbid water and by analyzing the material de- posited on the vegetation. Second, the effects of small carp, which were relatively abundant in the Sago sample area (Chapter IV.), may be as significant as the more obvious effects of the adults. In summary, my observations lead me to believe that the activities of carp, as presently understood, can- not maintain all the turbidity present in Erie Marsh. When very dense vegetation is present, and possibly at other times as well, some sort of synergism may be operat- ing in the marsh which extends the effect of carp or nulli- fies the apparent two hour time limit imposed upon the suspended bottom material by Stokes' Law. A determination of the importance of this synergism, if it exists at all, is difficult. Possibly in 1965 and in other years when the carp pOpulation has not been depleted by recent poison- ings, carp have been present in sufficient numbers to maintain turbidity in the usually hypothesized manner. The impact of the carp upon the vegetation during 1965 91 and the estimate by King of densities between 100 and 200 individuals per acre that year in North Bay is sufficient to make this creditable. The effects of turbidity: The second question raised by the observations of turbidity in Erie Marsh concerns the effect of the turbidity upon the aquatic vegetation. As described in the previous section, turbidity is virtually unavoidable in the marsh. Following every poisoning, none of which may have been 100% effective, carp were rapidly recruited through the weir, and even low densities of carp in North Bay seem to produce turbidity and depo- sition of silt on areas remote from carp activity. .Also, the poisonings have always occurred near the period of maximum standcrOp, and, thus, after the period of maximum productivity (Wetzel, 1964:38-39)° Consequently, compara- tive data on plant biomaSs in the absence of turbidity has been impossible to obtain. That evidence which is avail— able is inconclusive. The anélysis of the exclosure data indicates that the direct effects of carp upon the vege- tation, i.e. mechanical uprooting and direct consumption, were not felt at the sample areas in 1964. But the exclosures could not exclude turbidity, and the effect of 92 turbidity must have been the same in both exclosures and controls. The biomass and productivity data give no indi— cation of what productivity might have been if turbidity was absent. Hunt (1958:22) observed regrowth of the aquatic vegetation following the 1958 poisoning, but this could have been due to the cessation of the mechanical effects of carp, alone. It seems to me that regardless of wind caused tur- bidity early in the season (King, 1965:95), turbidity caused by carp could be important in terms of absolute primary productivity because the effects of carp caused turbidity are felt most at the time of maximum photosynthetic display, i.e. in the middle of the growing season when the effects of wind are minimized by the plant mat. Further, although turbidity caused by wind action may be significant early in the season, carp must'make an important contribution to this at the time by their breeding activities, which start in April continue through May (King, 1965:25—27). As pre- viously mentioned, the turbidity produced by carp may have the ability to circulate through the marsh even if the area used by carp is quite limited. ,Concerning the turbidity present during the middle part of the season, i.e. that caused by carp, King stated 93 the opinion that this was not important at depths less than 18 inches and where secchi disk readings are greater than 12 inches (1965:65). I assume this opinion is based upon observations that the vegetation remains very vigorous and dense in spite of the turbidity. If so, I agree with the observations but feel that the effects of turbidity may be expressed in more subtle terms than plant bulk. Foster (l962:3) observed that leaves of criSpus pondweed covered with silt were tranSparent. My observa- tions confirm this, although in my experience only lower leaves were affected in this Way, even when silt had been deposited over the whole plant. Assuming that the trans- parent leaves are not photosynthetically active and that the plant reSponds to this by producing more leaves and supporting structures, the possibility arises that plant biomass and photosynthetic activity are not well correlated. In other words, a plant responding to the presence of silt must create more biomass that a plant not bothered by silt to intercept the same amount of light energy. This greater investment of energy and nutrients in photosyn- thetic machinery might result in decrease in the produc- tion of seeds and other energy storing structures. If there is any relationship between the production of these 94 and the attraction of ducks to the marsh, the results of carp caused turbidity may be of practical importance. A study of a nearby and apparently similar area by Anderson (1950) may support this hypothesized relationship between turbidity and seed production. Working at Middle Harbor, Ohio, Anderson found that seed production by sago pondweed was limited to May and June in the presence of carp and turbidity. The following year, after the carp had been . poisoned out and a significant increase in water transpar— ency, he discovered that seed production was stimulated to continue through early Fall. Table 16 indicates that seed production continued through August in Erie Marsh in 1964, but the amount of production may still have been affected. There is a possibility that the effects of carp are not entirely detrimental to vegetation. Dr. Miles D. Pirnie, who is familiar with the Erie Marsh and similar. areas in the mid—west, thinks that in some situations carp may provide Open, "cultivated" spots on the bottom which may be required for the germination of some species (per— sonal communication). Also, recent work by Dr. Robert G. Wetzel (1965) indicates that organic molecules may chelate certain nutrients, making them available to plants when they might otherwise be limiting. There may be enough 95 organic matter in the bottom material turned over by the carp at Erie Marsh to be significant in this respect. VII. CONCLUSIONS Excluding the direct*effects of carp had no signifi- cant effect upon the aquatic macrophytes of the sample areas during the second half of the growing season in 1964. The analysis of the depth data indicates that carp were present in the sample areas in 1964 in sufficient numbers to have a significant effect on the bottom tOp— ography. Plant growth between May 1 and July 4, 1965, was esti- mated at 107.4 grams organic weight/meter2 in the Sago area and 46.2 grams organic weight/meter2 in the Crispus area. The average primary productivity by macrophytes during this period (64 days) was estimated at 1.7 grams organic weight/meterZ/day in the Sago area and 0.7 grams organic weight/meterZ/day in the Crispus area. Many factors, including the indirect effects of carp 96 97 the presence of several other species of fish may affect the standing crop, productivity, and duck food production by the aquatic macrophytes in the marsh. LITERATURE CITED Anderson, J. M. 1950. Some aquatic vegetation changes following fish removal. J, Wildl. Mgt. 14(2): 206-209. Bennett, C. L., Jr., W. A. Matulis, and D. J. Drumm. 1961. Report of research studies at the Erie Shooting Club Marsh for 1961. Unpublished report to the Erie Research Committee. 10 pp. Black, J. D. 1946. Nature's own weed killer - the german carp. Wisc. Cons. Bull. 11(4):3-7. Drumm, D. J. 1961. Cattail study summary. In; Bennett, C. L. et a1. 1961. Report of research studies at the Erie Shooting Club Marsh for 1961. Unpublished report to the Erie Research Committee. 10 pp. Eby, C. F. 1958. Soils survey of the Erie Shooting Club. Unpublished report to the Erie Research Committee. 21 pp. Eddy, S. 1957. How to know the freshwater fish. Dubuque, Iowa, wm. C. Brown Company, 153 pp. Eddy, S. and A. C. Hodson. 1962. Toxonomic Keys to the Common Animals of the North Central States. Minne- apolis, Burgess Publishing Company, 162 pp. Foster, J. R. 1962. Report on researches at the Erie Marsh summer 1962. Unpublished report to the Erie Re- search Committee. 6 pp. Foster, J. R. 1963. Report on researches at the Erie Marsh. Unpublished report to the Erie Research Committee. 11 pp. 98 99 Guenther, W. C. 1964. Analysis of Variance. Englewood Cliffs, N. J., Prentice-Hall, Inc., 199 pp. Hunt, G. S. 1957. Report of Surveys on the Erie Shooting Club area. Unpublished report to the Erie Research Committee. 60 pp. Hunt, G. S. 1958. Report of surveys on the Erie Shooting , Club area. Unpublished report to the Erie Research Committee. 60 pp. . 1959. Report of surveys on the Erie Shooting Club area. Unpublished report to the Erie Research Committee. 34 pp. Irwin, W. H. 1945. Methods of precipitating collodial soil particles from impounded water of central Oklahoma. Bull. Okla. 59: and.Mech. Col. 42:1-16. Irwin, W. H. and J. H. Stevenson, 1951. Physiochemical nature of clay turbidity with Special reference to clarification and productivity of impounded waters. Bull. Okla. Ag, and Mech. Col. 48: 1-54. King, D. R. 1965. The effect of carp on aquatic vegetation at the Erie Marsh, Monroe County, Michigan. Unpub— lished Master's Thesis, The Univ. of Mich., Ann Arbor. vii 126 pp. Matulis, W. A. and M. D. Pirnie. 1960 Report of research studies at the Erie Shooting Club Marsh. Unpub- lished report to the Erie Research Committee. 8 pp. Miller, C. E., L. M. Turk, and H. D. Foth. 1965. Funda- mentals of Soil Science. N. Y., John Wiley and Sons, Inc. Pirnie, M. D. and J. R. Foster. 1964. Summary of Erie researches 1960-64. (By Michigan State University students.) Unpublished Report to the Erie Research Committee. 28 pp. 100 Robel, R. J. 1961. The effects of carp pOpulations on pro- duction water fowl food plants on a western water- fowl marsh. Trans. 26th NR Am, Wildl. E232 BEE: Conf. 26:147-159. Tack, P. I. and J. Singh. 1959. Fish removal at the Erie Shooting Club. Unpublished report to the Erie Re- search Committee. 17 pp. ' Threinen, C. W. and W. T. Helm. 1954. EXperiment and observation designed to show carp destruction of aquatic vegetation. g, Wildl. Mgt. 18(2): 247- 251. U. S. Weather Bureau. 1964. Local climatological data with comparative data, 1965, Toledo, Ohio. 4 pp. 1965. Local climatological data with com- parative data, 1964, Toledo, Ohio. 4 pp. Westlake, D. F. 1963. Comparisons of plant productivity. Bio. Rev. 38:385-425. Wetzel, R. G. 1964. A comparative study of the primary productivity of higher aquatic plants, periphyton, and phytoplankton in a large, shallow lake. £33, Revue ges. Hydrobiol. 49(1): 1-61. . 1965. .Nutritional aspects of algal productivity in marl lakes with particular reference to enrich- ment bioassays and their interpretation. HST: EEE- Idrobiol., 18 Suppl.:l37-157. Wood, J. S. 1962. Report on Erie Marsh fish poisoning. Unpublished report to the Erie Research Committee. 3 pp. APPENDIX I Results of Soil Analysis i I Laboratory Analy81s: Pounds per Acre Available Sample Lab No. pH p K Ca Mg Crispus 18848 7.5 14 177 7920 517 Sago 18849 7.5 2 197 7440 404 Mechanical Analysis: Sample % Sand* % Silt* %.Clay* Crispus 18.40 72.32 9.28 17.44 79.72 2.78 12.56 86.62 0.72 Average: 16.13 79.55 4.26 Sago 8.48 86.17 5.35 10.08 84.28 5.64) Average: 9.28 85.23 5.50 *Equivalent spherical Diameter: Sand: 0.05 - 2.0 mm. Silt: 0.002 - 0.05 mm. Clay: less than 0.002 mm. 101 APPENDIX II Estimated Mean Sums of Squares for the 3-Way Analysis of Variance: Plant Samples Source EMSS F A (fixed) 6 2 ' 62 52 52 ('1 Z .. + e+bcn a +cn AB bn AC+n ABC * B (random) 6 62 62 + . + e acn B an BC B/BC C (random) 5 62 62 + e abn C +an BC C/BC AB 6 2e+cn 62 +n 62 AB ABC AB/ABC AC 6 62 + 62 e+bn AC n ABC AC/ABC BC e+an 62 BC BC/E ABC 6 e+n 62 ABC ABC/E Error 5 2 e *F - A/AB+AC ABC i e +AB - +62e+cn62 + n62 A ' ' ° ' AB ABC 52 62 62 + = AC + e+bn AC+ n ABC 52 62 —ABC— 4 e - n ABC 62e+ 62 +bn62 +n62 C“ AB ‘ AC ABC . + _ Degree of freedom. MSAB MSAC MSABC 2 2 2 (MSAB) + (MSAC) - (MSABC) (a—l)(b-1) (a-l)(b-1) (a-l)(b-l)(c—1) 102 Estimated Mean Sums of Squares for the 3-Way APPENDIX III Analysis of Variance: Depth Data E Source EMSS F A (fixed) 52 62 52 62 + + “be A “C AB n ABC A/AB* B (random) 62 nac 62 B B/E c (random) 62 62 52 52 “ab c + “a BC + n ABC C/BC AB 62 nc 62, n 62 AB ABC AB/ABC AC 52 62 62 nb Ac+ n ABC AC/ABC BC 52 na 62 n 62 BC ABC BC/ABC ABC 62 *Note: MSAB' the denominator for component A, is also used as the denominator in the individual degree of freedom computations. 103 U @lllfl‘lll miclfilllliiilmllfilinllll 3129310