DISTINCT PATTERNS OF CHANGE IN ZOOPLANKTON COMMUNITIES OVER MULTIPLE SUMMERS IN A EUTROPHIC RESERVOIR

Much research on plankton dynamics has focused on glacially-formed, north temperate lakes, leaving a gap in our understanding of the variability and community succession of zooplankton in reservoirs. Zooplankton play a central role in freshwater food webs, and thus changes in their communities can have cascading effects on other freshwater organisms. While it is widely expected in glacially-formed lakes that zooplankton communities follow predictable patterns of succession within a year, reservoirs may exhibit less predictable patterns, especially as climate change exacerbates variability. To identify the predictability of zooplankton succession, we collected monthly zooplankton samples from May-September over six years in a eutrophic reservoir. We used multivariate approaches to compare the trajectory of zooplankton succession among cladoceran, copepod, and rotifers each year. Our goals were to: 1) determine whether zooplankton followed similar patterns of succession and 2) identify environmental drivers of zooplankton succession. We found that zooplankton communities followed predictable patterns of succession in some years, but observed high variability in zooplankton density and community composition from year-to-year. Additionally, dissolved oxygen and nutrient concentrations were associated with variability between months and years. Ultimately, our data suggest that zooplankton succession in reservoirs inconsistently follows expected patterns from glacially-formed lakes, and this seasonal variability may further increase in the future due to climate change.

Primary Presenter: Heather Wander, Virginia Tech (hwander@vt.edu)

Authors:

Heather Wander, Virginia Tech  (hwander@vt.edu)

Jonathan Doubek, Lake Superior State University  (jdoubek@lssu.edu)

Bryan Brown, Virginia Tech  (brown51@vt.edu)

Cayelan Carey, Virginia Tech  (cayelan@vt.edu)