SEASONAL DISTRIBUTION OF PLANKTON SPECIES AMONG SEVEN FINGER LAKES IN NEW YORK STATE

As the foundation of lake ecosystems, plankton have short carbon-turnover rates and are sensitive to water quality parameters. This should make them good indicators of the trophic status and ecological health of lakes. Preliminary limnological data collected in 2005 (nutrient, P, N and Si, and algal concentrations, turbidity and conductivity) were used to rank the ecological health of the seven central Finger Lakes (Honeoye, Canandaigua, Keuka, Seneca, Cayuga, Owasco and Skaneateles). The health of these lakes is critical to the surrounding communities because they rely on them for drinking water and as a driving force for regional tourism. This study investigates the distribution of plankton species in the Finger Lakes to determine whether seasonal distribution of the dominant taxa is consistent with the limnological data.

Horizontal and vertical (20 m deep) plankton tows were taken at two or more sites on each lake each month from mid June to the beginning of September, 2005 and preserved in a 6-3-1 formalin solution. Over 100 individuals (colonies as one individual) were identified from each sample in the lab to calculate the relative percentages of each species. Some common trends and differences in species distribution were observed among the seven lakes in this study. Limnological data were referenced to help explain these trends. All seven lakes show diatoms as the majority species during the late spring and early summer. Diatoms then appear to decline in late summer/early fall and are replaced by other species. The lakes differed in the number of diatoms present in the beginning of the season, the rate of decline, and the specific species that emerged following the diatom decline. Future research will compare the relative distribution of particular species with the presence or absence of certain nutrients (e.g., dissolved silica concentration), intensity of sunlight, dissolved oxygen, temperature and the overall ecological health of the lakes.