Zooplankton diversity and density versus fish stocking in Vermont waters

Zooplankton form the basis of the consumer level of many aquatic food chains and respond to changes in fish predation and food source. This study conducted a survey of zooplankton found in three Vermont lakes with different levels of fish stocking. Horizontal and vertical plankton tows were taken in each lake. The main characteristics examined were zooplankton type, size, and abundance, surface water chlorophyll A and the physical properties of the lake. These were used alongside the recorded values of fish stocking to find that stocking does have a noticeable impact on zooplankton. Twin Ponds had the lowest chlorophyll A concentration at 0.0007 ug/L , and the lowest concentration and diversity of zooplankton. Rood Pond and Sunset Lake had higher concentrations of chlorophyll A at 0.0013 ug/L and 0 .0027 ug/L, respectively, larger concentrations of zooplankton and a greater diversity than the smaller and less deep Twin Ponds. These results also show that the presence of more fish decreases the number of larger zooplankton and leads to a larger diversity of small zooplankton. The differing amounts of primary productivity and lake habitat diversity also contribute to the observed differences between the zooplankton populations.