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0 Meter. Nitrogen/ Alkalinity. Algae, Canopy, Temp. 50 Meter. Snails, Substrate. 100 Meter. I. Introduction. IV. Results. Table 1. Average density, snails m -2 , and average biomass, g m -2 , with associated limits.
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0 Meter Nitrogen/ Alkalinity Algae, Canopy, Temp. 50 Meter Snails, Substrate 100 Meter I. Introduction IV. Results Table 1. Average density, snails m-2, and average biomass, g m-2, with associated limits. - Study sites: Four 1st order streams, Nantahala National Forest, North Carolina. - Life history and secondary production study designed to gain insight into organism behavior such as reproduction, growth, and habitat and resource utilization. - Secondary production is useful in determining how efficient an organism utilizes it’s food source and how ‘successful’ that organism is. Life History and Secondary Production of Goniobasis proxima (Prosobranchia: Pleuroceridae) from Four Appalachian Headwater Streams in Western North Carolina.N.G. Jeremiah and E.F. Benfield; Department of Biological Sciences, Virginia Polytechnic Institute and State University, Blacksburg Va. 24061. Table 2. Correlation p-values between snail density to chlorophyll α and algal AFDM. Figure 1. Average percent substrate available to snails. Figure 2. Average percent substrate snails were using. II. Methods Sampling: Monthly from July 2005 - June 2006. Stream Measurements: Algal Biomass, Substrate, Alkalinity, NO3-N, Canopy Cover, Temperature, Conductivity. Snail Measurements: In-stream measurements of snail width and density and substrate using 1/2m grid. In-lab microcosm to establish individual snail growth rate. Table 3.Production given in mg m-2 y-1. P/B ratio (turnover rate) is per year. Figure 3. Snail abundance across streams, July 2005 – June 2006. Figure 4. Snail growth from microcosm experiment. III. Sampling Design V. Discussion / Conclusions - Snail populations prefer rock and allochthonous substrates to sand (Figures 1 & 2), display seasonal variation in abundance (Figure 3) we suspect to be temperature driven, grow faster when smaller (Figure 4) and have no appreciable grazing effect on the algal community except for AFDM in 30m (Table 2). - Low P/B ratios indicate long development times which coincide with our data suggesting these snails can live for approximately 10 years (Table 3). - Production is extremely low when compared to other snail production studies; 194 g m-2 y-1 (Hall 2006). - Production may be limited due to physical barriers preventing snail migration upstream, low quality and quantity of food sources, and inadequate stream water chemistry.
