38 Macrobenthic study of the northern tributaries of Otsego Lake, summer 1998 Aaron Vanderlipl INTRODUCTION During the summer of 1998, macrobenthic collections were taken from four main tributaries that empty into the northern end of Otsego Lake: Cripple Creek, Hayden Creek, Shadow Brook, and White Creek. Twenty-one samples were taken at various locations along these waterways. A similar study was executed three years ago (Fahey, 1995). The 1998 collections were both qualitative and quantitative, giving a list of the invertebrates that inhabit the tributaries along with numerical data to show diversity, dominance, and abundance within these streams. Some conclusions regarding the health of these waters can be expressed by looking at their population profiles, and using the various taxa as indicators of water quality. For example, the orders Trichoptera (caddisflies), Plecoptera (stonetlies), and Ephemeroptera (mayflies) (EPTs) are generally considered good indicators of a high level of oxygen in the water; therefore, their presence and abundance serves as a good indication of a stream's health. The final results of this study, in conj unction with the results of geological/geochemical analysis (Fetterman, 1998), chemical analysis (Poulette, 1998), and fecal bacterial monitoring studies (Ingraham, 1998), will give us a better understanding of the water quality of these tributaries, and ultimately, Otsego Lake. MATERIALS and METHODS Samples of macrobenthic organisms were collected 2-4 June 98 at 21 different locations on 4 different tributaries. These included five sites on Cripple Creek, eight on Hayden Creek, five on Shadow Brook, and three on White Creek (Figure 1). Triangle nets, hand sieves, seines, and soft forceps were used to obtain invertebrates for the qualitative samples. They were actively collected dragging a hand sieve or a triangle net through the substrate, along the bank, or through the vegetation of the stream. Also rocks, dead logs and stems, and any larger items found in the stream were searched for invertebrates by using soft forceps. Organisms were also passively collected by stirring up the bottom of the stream and letting the current wash the organisms into the various nets, sieves, and seines, where they could be picked out. These types of samples were done in as many of the microhabitats at each sampling site as possible, so as to give the best representation of the number of different taxa. The quantitative samples were generally done in the riffles of the streams, where available. Qualitative samples were generally collected using a Hess Sampler. The Hess has a sample space of 0.085 meters 2 • It is placed in the riffle so that the collection cup faces down cunent. The area that the sampler encompasses was stirred up by hand, so that the invertebrates were washed down into the collection cup by the current. Larger rocks and debris inside the 1 Capstone experience, SUNY Oneonta, Environmental Sciences program, summer 1998
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Macrobenthic study of the northern tributaries of Otsego Lake, summer 1998
Aaron Vanderlipl
INTRODUCTION
During the summer of 1998, macrobenthic collections were taken from four main tributaries that empty into the northern end of Otsego Lake: Cripple Creek, Hayden Creek, Shadow Brook, and White Creek. Twenty-one samples were taken at various locations along these waterways. A similar study was executed three years ago (Fahey, 1995). The 1998 collections were both qualitative and quantitative, giving a list of the invertebrates that inhabit the tributaries along with numerical data to show diversity, dominance, and abundance within these streams. Some conclusions regarding the health of these waters can be expressed by looking at their population profiles, and using the various taxa as indicators of water quality. For example, the orders Trichoptera (caddisflies), Plecoptera (stonetlies), and Ephemeroptera (mayflies) (EPTs) are generally considered good indicators of a high level of oxygen in the water; therefore, their presence and abundance serves as a good indication of a stream's health. The final results of this study, in conj unction with the results of geological/geochemical analysis (Fetterman, 1998), chemical analysis (Poulette, 1998), and fecal bacterial monitoring studies (Ingraham, 1998), will give us a better understanding of the water quality of these tributaries, and ultimately, Otsego Lake.
MATERIALS and METHODS
Samples of macrobenthic organisms were collected 2-4 June 98 at 21 different locations on 4 different tributaries. These included five sites on Cripple Creek, eight on Hayden Creek, five on Shadow Brook, and three on White Creek (Figure 1). Triangle nets, hand sieves, seines, and soft forceps were used to obtain invertebrates for the qualitative samples. They were actively collected dragging a hand sieve or a triangle net through the substrate, along the bank, or through the vegetation of the stream. Also rocks, dead logs and stems, and any larger items found in the stream were searched for invertebrates by using soft forceps. Organisms were also passively collected by stirring up the bottom of the stream and letting the current wash the organisms into the various nets, sieves, and seines, where they could be picked out. These types of samples were done in as many of the microhabitats at each sampling site as possible, so as to give the best representation of the number of different taxa. The quantitative samples were generally done in the riffles of the streams, where available.
Qualitative samples were generally collected using a Hess Sampler. The Hess has a sample space of 0.085 meters2
• It is placed in the riffle so that the collection cup faces down cunent. The area that the sampler encompasses was stirred up by hand, so that the invertebrates were washed down into the collection cup by the current. Larger rocks and debris inside the
Figure 1. Map of the 21 sampling sites on five major tributaries in the Otsego Lake watershed (Adapted from Paulette, 1998).
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sample area were examined and picked of all the organisms that were still clinging to them. At each site two of these Hess samples were taken.
In both the qualitative and quantitative samples, the organisms were preserved in 70% ethyl alcohol in labeled jars and taken back to SUNY Oneonta Biological Field Station. Once back at the field station, the qualitative samples were classified to their respective orders, and within the orders classified down as specifically as possible using taxonomic keys (Harman & Berg, 1971; Merritt & Cummings, 1996; Peckarsky et al., 1990; Pennak, 1953; Harman, 1998). The quantitative samples were dealt with in a different fashion. Once at the field station, a Rose Bengal solution was added to all of the sample jars to stain the organisms, making the removal of organisms and the subsequent removal of detritus easier. After this, the samples were examined under an illuminated magnifier', so that the stained organisms could be picked out of the sediment more efficiently. Once this process was complete, the organisms were keyed to order using the same taxonomic keys.
RESULTS
The results of the qualitative samplings are shown in Tables 1-4. The results of the quantitative samplings are shown in Tables 5-8.
DISCUSSION
When comparing the results of the qualitative samples that were collected on 3 June 98 with those taken on 30 June 95 (White Creek was not in the 1995 study), there was a noticeable increase in the number of sample sites inhabited by Plecoptera, Ephemeroptera, and various orders of Crustacea. There were no Plecoptera at any of the Shadow Brook sites in 1995; they are now located at all five sites, which leads to the belief that the overall health of the stream is improving. There also seems to be a greater diversity of genera per site and stream in 1998 than in 1995. This seems to be the case at every stream and across most sampling sites. Any decrease in the amount of genera was slight and almost unnoticeable. The reason for this could be an increase in the quality of the stream. However, the temporal differences in sampling dates between 1995 and 1998 is over three weeks. This could also explain some differences; in 1995, some of the aquatic insects may have had a chance to complete their life cycles and leave the stream. No conclusions can be drawn from the quantitative data at this time.
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Table 1. Summary of the macrobenthos samples taken from Cripple Creek, summer 1998.
Table 8. Quantitative analysis ofthe macobenthos samples taken from White Creek, summer 1998.
REFERENCES
Fahey, J. 1995. Benthic Survey of Otsego Lake Tributaries. In 28th Annual Report, SUNY Bio. Fld. Sta., SUNY Oneonta.
Harman, W. N. 1998. Handout on Leeches. Aquatic Biology 384. SUNY Oneonta. 1998.
Hewett, B. L. 1996. Water quality monitoring and benthic community in the Otsego Lake watershed. In 29h Annual Report, SUNY Bio. Fld. Sta., SUNY Oneonta.
Merritt, R. W. and K. W. Cummings. 1996. Aquatic Insects of North America. Kendall/Hunt Publishing Company. Dubuque,lA.
Peckarsky, B. L., P. R. Fraissinet, M. A. Penton, and D. 1. Conklin, Jr. 1990. Freshwater Macroinvertebrates of Northeastern North America. Cornell University Press. Ithaca, NY.
Pennak, R. W. 1989. Freshwater Invertebrates of the United States, 3rd Ed. John Wilet and Sons, Inc. New York.