ESTABLISHING A BASELINE OF LITTORAL ZOOPLANKTON ABUNDANCE IN THE FREDONIA RESERVOIR IN POMFRET, NY

The Fredonia Reservoir in Pomfret, New York, is a freshwater reservoir which is fed by runoff from the surrounding watershed, and which provides water to the village of Fredonia for domestic and commercial use. While algae and phytoplankton samples have been collected for the monitoring of harmful algal blooms and reservoir water quality in the past, no baseline for zooplankton presence or abundance in the reservoir has been established since the creation of the reservoir in 1884. Many species of zooplankton can be used as bioindicators of water quality and eutrophication due to their responses to changing water quality conditions and short life cycles. Establishing a comparative baseline for the presence of these indicator species is essential in order to monitor future changes in abundance.

This paper documents the diversity of zooplankton sampled from a littoral zone on the Northeastern shore of the Fredonia Reservoir in Fall of 2024. Five samples were collected, and from two samples taken on September 9th and 15th, 3660 specimens of zooplankton were individually sorted into nine categories: class Insecta, class Arachnida, class Ostracoda, class Copepoda, class Malacostraca, class Branchiopoda (further divided into order Ctenopoda and order Anomopoda), ephippia, and non-arthropods. In both samples, order Anomopoda made up the highest percentage of arthropod zooplankton, with 40.7% and 70.5% respectively, followed by class Ostracoda (19.3% and 18.7%). The Shannon Diversity Index was calculated for each sample and compared using a Hutcheson t-test. The sample taken on September 9th was significantly more diverse than the sample taken on September 15th.

A total of 31 representative specimens from each group of subphylum Crustacea were examined and photographed under a scanning electron microscope and nine species from seven families were identified, including Hyalella azteca, a bioindicator commonly used in water toxicity assessment, Sida crystallina, a littoral indicator of water pH, and Eucyclops agilis. Further sampling and identification of zooplankton species in the Fredonia Reservoir may further provide a baseline for zooplankton abundance and presence of indicator species which can be used to monitor the reservoir water quality in the future.