Macroinvertebrate survey and biological assessment of water quality: tributaries of Canadarago Lake; Otsego County, NY 1 Carter Bailey 2 INTRODUCTION Generally, invertebrate organisms have a wide geographic distribution, making it fairly easy to predict which types should be present where. By identifying the different aquatic macroinvertebrates present in a given area it is possible to conduct a biological assessment of water quality (NY-DEC 2009). Different macroinvertebrate populations are associated with varying degrees of water quality and water quality impact (Hilsenhoff 1988). Macroinvertebrate sampling is also commonly thought to be more of a long-term assessment of water quality compared to a water sample. A water sample is simply a snapshot of the given stream conditions for that day at that time, while invertebrate populations tend to react slower to longer-term changes in water quality. Sampling them measures an environmental component with a direct impact on the health of the community itself. This study is intended to complement the ongoing water quality research being conducted on Canadarago Lake (Bailey & Albright 2009) and the development of a State of the Lake report by providing a long term indication of tributary health and water quality within the Canadarago watershed. MATERIALS AND METHODS Benthic macroinvertebrate samples were collected from the four main tributaries of Canadargo Lake on 20 July 2010. These include Herkimer Creek, Hyder Creek, Trout Brook, and Ocquionis Creek (Figure 1). All tributary sampling sites were similar to those outlined in Bailey & Albright (2009), though some modification was necessary so that the sampling was done in riffle areas (NYS-DEC 2009). Sampling was conducted using a Wildco Hess Sampler (13 ID x 16 ) outfitted with a 600µm mesh sock and sample cup. This sampler is a hollow aluminum cylinder with holes on the upstream and downstream sides of the device to allow stream flow through the device. The Hess Sampler is inserted at least 2 into the creek bed. As the current sweeps though it, the user agitates the benthic substrate within the sampling ring, disrupting any organism which may occur within the area. All disrupted organisms are carried to the sampling cup via the downstream water current running through the device. Once collected, samples were jarred, preserved to 70% ethanol and brought back to the lab for identification. All organisms found were keyed out to the family level. A biological assessment of water quality was then conducted by converting recorded taxa to four common water quality indices used to determine the health of a riffle community. These indices included taxa richness, Ephemeroptera-Plecoptera-Trichoptera (EPT) richness, Family-level Biotic Index (FBI), and Percent Model Affinity (PMA). This method varies slightly from the NYS-DEC Biological Assessment of Water Quality which calls for species richness and Hilsenhoff s Biotic Index (HBI) indices (NYS-DEC 2009). These two indices were substituted with taxa richness and Family-level Biotic Index (FBI) (Hilsenhoff 1988), due to the family level identification conducted during this study. Although these changes were made in indices, the 1 Funding for this work was a multi-sponsor contract administered through the Otsego County Soil and Water Conservation District, Cooperstown, NY. 2 Biological Field Station Intern, summer 2010. Present Affiliation: SUNY ESF.
standard Biological Assessment Profile (BAP) chart of index values for riffle habitats (NYS-DEC 2009) was used to report water quality and water quality impact values. These minor adjustments were considered to have little impact on the actual water quality scores and were undertaken to create a more rapid assessment structure. Figure 1. Map of Canadarago Lake showing sites used for macrobenthic collections, summer 2010.
RESULTS AND DISCUSSION A summary of total collected organisms for Herkimer Creek, Hyder Creek, Trout Brook and Ocquionis Creek can be found in Table 1. Biological assessment of water quality charts for those streams can be found in Figures 2-5, respectively. Figure 6 sumarizes the indices for all streams. Herkimer Creek contained the highest level of chironomids (non-biting midges), yielding 116 specimens; these are commonly associated with poor water quality. Herkimer scored the lowest in the water quality assessment, averaging a 2.6, just outside the severely impacted category (Figure 2). The largest concentration of oligochaets (aquatic worms), an indicator of poor water quality (Hilsenhoff 1988), was found in Hyder Creek with 192 observed within the sampling area. Hyder averaged a 2.9 on the common water quality scale. Trout Brook scored the highest within the Percent Model Affinity (PMA) index with a score 63 (Figure 4). This stream averaged a 4.6 on the common water quality scale, well within the moderately impacted zone. Ocquionis Creek, which clearly displayed the highest level of diversity (15 different taxa), also scored the highest within the Ephemeroptera-Plecoptera-Trichoptera (EPT) richness (6 taxa) and Family-level Biotic Index (FBI) (46). Organisms from within the Ephemeroptera-Plecoptera-Trichoptera orders are known to be indicators of good water quality (Voshell 2002). Ocquionis also displayed the overall best stream quality, averaging a 5.4 on the common scale and ranking slight impact on the water quality impact scale (Figure 5). Herkimer Creek Taxa: Number of Organisms Hyder Creek Taxa: Number of Organisms Diptera Diptera Unknown 2 Unknown 2 Chrinomidae 116 Chrinomidae 92 Hemiptera Oligochaeta Corixidae 3 Unknown 192 Notonectidae 3 Ephemeroptera Oligochaeta Caenidae caenis 5 Unknown 6 Trichoptera Ephemeroptera Limnephilidae 3 Caenidae caenis 8 Coleoptera Coleoptera Elmidae 8 Elmidae 3 Psephenidae 1 Psephenidae 1 Decapoda Decapoda Orconectes 1 Orconectes 9 Palaemonidae 10 Total 151 Acariformes Hydracarina 2 Total 316 Table 1. Summary of the benthic invertebrates collected in the Canadarago Lake watershed, summer 2010.
Trout Brook Taxa: Number of Organisms Ocquionis Creek Taxa: Number of Organisms Diptera Diptera Chrinomidae 53 Unknown 2 Oligochaeta Chrinomidae 24 Unknown 16 Oligochaeta Hemiptera Unknown 24 Unknown 1 Ephemeroptera Ephemeroptera Heptageniidea 9 Metreopodidae 33 Baetidae 3 Trichoptera Trichoptera Hydropsychidae 34 Leptoceridae 6 Plecoptera Hydropsychidae 8 Perlidea 2 Plecoptera Coleoptera Perlidea 5 Elmidae 112 Leuctridea 5 Decapoda Coleoptera Palaemonidae 9 Elmidae 75 Gastropoda Psephenidae 1 Lymnaeidae 2 Megaloptera Total 262 Sialidae 3 Decapoda Orconectes 116 Palaemonidae 2 Gastropoda Sphaeriidae 6 Total 289 Table 1 (cont.). Summary of the benthic invertebrates collected in the Canadarago Lake watershed, summer 2010.
Figure 2. Herkimer Creek, Biological Assessment Profile (BAP) of index values for riffle habitats. Values from four indices; taxa richness, EPT richness, Family-level Biotic Index (FBI), and Percent Model Affinity (PMA) are converted to a common 0-10 scale as shown in this figure. The mean value of the four indices represents the assessed impact for the site.
Figure 3. Hyder Creek, Biological Assessment Profile (BAP) of index values for riffle habitats. Values from four indices; taxa richness, EPT richness, Family-level Biotic Index (FBI), and Percent Model Affinity (PMA) are converted to a common 0-10 scale as shown in this figure. The mean value of the four indices represents the assessed impact for the site.
Figure 4. Trout Brook, Biological Assessment Profile (BAP) of index values for riffle habitats. Values from four indices; taxa richness, EPT richness, Family-level Biotic Index (FBI), and Percent Model Affinity (PMA) are converted to a common 0-10 scale as shown in this figure. The mean value of the four indices represents the assessed impact for the site.
Figure 5. Ocquionis Creek, Biological Assessment Profile (BAP) of index values for riffle habitats. Values from four indices; taxa richness, EPT richness, Family-level Biotic Index (FBI), and Percent Model Affinity (PMA) are converted to a common 0-10 scale as shown in this figure. The mean value of the four indices represents the assessed impact for the site.
Figure 6. Mean values all sites, Biological Assessment Profile (BAP) of index values for riffle habitats. The mean value of the four indices represents the assessed impact for each site. CONCLUSION Clearly displaying the highest level of diversity and scoring the highest on the common water quality scale with a 5.4 (Figure 6), Ocquionis Creek appeared to be the least impacted of the four sites sampled within the Canadarago watershed. There is most likely a process or processes taking place within the Herkimer Creek and Hyder Creek basins which are negatively affecting macroinvertebrate stream life. These two sites yielded the lowest common water quality scores, Herkimer 2.6 and Hyder 2.9 (Figure 6). Results from ongoing studies within the Canadarago watershed may offer more insight into possible reasons behind these moderate/severe impacted rankings. This method appeared to be an effective tool for quickly understanding and interpreting macrobenthic population composition in terms of water quality.
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