The Abundance and Decomposition of Coarse Particulate Organic Matter in Man-Made Ponds in Central Virginia
Globally, man-made ponds and reservoirs approach the abundance of natural lentic systems. Furthermore, in regions that lack natural lakes, man-made ponds tend to be the dominant lentic habitat. However, our knowledge of the ecology and biogeochemistry of man-made ponds lags behind that of natural systems. In natural ponds allochthonous detritus input can represent a substantial proportion of the total organic matter budget. The decomposition of this detritus supports macroinvertebrates and fuels production across trophic levels. Our project investigates whether the role and regulation of allochthonous litter decomposition in man-made ponds differs from this model. Spring sampling of 4 man-made ponds in central Virginia shows that the median coarse particulate organic matter (CPOM) pool, mainly comprised of allochthonous detritus, ranged 20 - 243 g m-2 and was variable among and within ponds. Comparison of CPOM density and the percent organic matter of the sediment, determined as loss on ignition at 550o C, shows a complex relationship between detritus input and sediment organic matter content. Direct measurement of decomposition using litter bags in 3 ponds during the fall and winter months showed similar mass losses across ponds. Unlike natural ponds, detrital mass loss appears to be due to microbial activity because virtually no shredding macroinvertebrates were recovered from the litter bags or the CPOM samples. These results suggest that the decomposition of allochthonous detritus is an important component of organic matter cycling in man-made ponds but that its regulation may rely on factors different from those identified from natural ponds.
Biological and Environmental Sciences, Longwood University, Farmville, VA
P55 • Charles R. Watt, Corey A. Swanson, Dillon A. Miller, Alaina C. Esposito, Christine L. May
Experimentation Reveals How Brook Trout Adapt Body Coloration to Match Substrate Conditions and Social Hierarchies
Phenotypic plasticity in fish is commonly used as a means of camouflage and as a means of intraspecific communication. The ability of resident trout to alter their coloration to match the local substrate, and how this is affected by stressors, is poorly understood. Experiments conducted in artificial stream channels with native brook trout tested for the potential of color matching by varying light and dark substrates, and included treatments with individuals as well as with paired cohorts to test for the effect of stress on this phenomenon. Fish displayed a broad ability to adapt their coloration to match a range of substrates. The baseline or resting colors that were established for dominant and subordinate individuals in paired trials showed trends that displayed the tendency for dominant fish to match to light substrate more effectively while subordinates displayed darker coloration; however, there was substantial variation among cohorts depending upon their aggressiveness. This ongoing research provides new insight into a form of camouflage not typically associated with salmonid fishes, and how it is mediated by social hierarchies.
Dept of Biology, James Madison University, Harrisonburg, VA
|
P56 • Pratikkumar P. Patel, Christina G. Duckworth, Erika L. Schumacher, Gretchen K. Bielmyer, Mattew N. Waters
Assessment of Heavy Metal Contamination in the Biota of Four Rivers With Varying Degrees of Human Impact
Changing land use may influence river ecosystems to varying degrees. Metal pollution in aquatic environments is a reported consequence of elevated anthropogenic inputs, particularly from densely populated areas. The objectives of this study were to quantify metal (Cu, Al, Cd, Ni, Pb) concentrations in the waters and biota of four streams (One Mile Branch, Sugar Creek, Withlacoochee River, and Little River) in South Georgia, each with varying levels of anthropogenic impact. Water and tissue samples from each stream were analyzed for metals using atomic absorption spectrometry. Additionally, the macrophytes and fish were identified to assess biodiversity at each site. Metal concentrations in fish tissue differed between sites and among species, corresponding to metal concentrations in the water for Cu but not for Al, Ni, Cd, and Pb. Withlacoochee (fourth order) and Little River (third order), both being heavily impacted by anthropogenic sources, contained the highest metal concentrations in the water but not in fish tissue compared to Sugar Creek and One Mile Branch (second order and first order streams, respectively). Macrophytes are still being analyzed for metals. The biological diversity of each sampling site was calculated using Shannon-Weiner and Simpson’s Index of Diversity. According to Simpson’s Index of Diversity, all streams were of similar community structure.
Biology Dept,Valdosta State University,Valdosta, GA
|
P57 • Autumn B. Forschler-Turner1, Terry D. Richardson
Effect of Total Suspended Solids on the Foraging Capacity of the Stream Snail, Pleurocera canaliculata
Total suspended solids (TSS) are thought to be among the leading non-point source pollutants contributing to habitat degradation and subsequent biodiversity decline in freshwater ecosystems. There is little conclusive information linking TSS and disruption of behaviors such as foraging among organisms that frequently encounter high levels of TSS in natural settings. This study directly examined the effects of increased TSS on the foraging capacity of the pleurocerid Silty hornsnail, Pleurocera canaliculata. Snails were offered weighed spinach disks during exposure to increasing levels of TSS. TSS exposure ranges for control were 0.0-5.0 NTUs, low 5.1-10.0, medium-low 10.1-20.0, medium-high 20.1-35.0, and high 35.1-55.0. These are comparable to natural levels ranging from <5.0 up to 55.0 NTUs. Feeding rate declined proportionately to increased TSS. Relative to mean control feeding rates of 11.77 mg/day (± 1.09 SE), consumption was significantly reduced to 6.71 (± 2.65) and 3.89 (± 1.12) for medium-high and high TSS exposure, respectively. Feeding rates at medium-high and high TSS exposure were also significantly lower than the consumption rates of 10.33 (± 2.21) and 13.62 mg/day (± 1.83) at medium low and low TSS exposure. Consumption rates for medium-low and low TSS exposure were not significantly different from control values. The decrease in feeding rate as a result of increased TSS suggests that natural levels of TSS may significantly impact foraging behavior in the Silty hornsnail. Such changes in foraging behavior that affect consumption rates, and subsequently energy budgets, could have long term consequences on snail fitness and survival.
1 Dept of Biology, University of North Alabama, Florence, AL
|
P58 • Manuel B. Bernal Mejia, Tonya C. Carver, Margaret K. Kovach
|
Share with your friends: |
