Quantification and Comparison of Phytoplankton Communities and Mortality Dynamics Between Two Small Freshwater Lakes: Implications for the Effects of Anthropogenic Influence on Freshwater Phytoplankton Ecology

Elaine Langone Center, Terrace Room

The classification of phytoplankton mortality dynamics is an expanding field of research that contributes extensively to our knowledge of primary production and energy flow in aquatic environments. Although the practice of determining growth and grazing rates of microalgae has existed since the 1980’s, the majority of present literature examines the marine or estuarine environment exclusively, leaving a noticeable lack of research surveying freshwater communities. This study aimed to contribute to this gap of data by documenting and comparing the community compositions and mortality dynamics of phytoplankton in two small freshwater lakes. Our study consisted of 6 paired dilution experiments conducted on Walker and Faylor Lakes of Snyder County Pennsylvania between September and October of 2017. Using methods of digital spectrophotometric analysis, Guava flow cytometry, and FlowCAM image assessment, we quantified and compared the bulk and size-specific phytoplankton growth rates, bulk microzooplankton grazing rates, and size/fluorescence-based community compositions between the two freshwater lakes. Due to variations in the biotic and abiotic conditions driven by anthropocentric pollution and direct manipulation, the community compositions and dynamics are predicted to vary significantly between the two lakes. The determination of phytoplankton mortality and community compositions in this study will ultimately allow for broader inferences on both the overall health of the lakes and the flow of energy/carbon within them.