The effects of eutrophication and invasive species on zooplankton community dynamics in a shallow temperate lake

Eutrophication (and associated cyanobacterial blooms) and biological invasions are increasingly common problems in aquatic ecosystems, yet their effects on zooplankton community dynamics are not well understood. We examined zooplankton community dynamics from 2005 to 2011 in a tidally-influenced shallow temperate lake (Vancouver Lake, Washington, USA), with particular emphasis on the effects of eutrophication and biological invasions. Cluster analysis, indicator species analysis, and non-metric multidimensional scaling analyses were used to explore interactions between the zooplankton community and multiple environmental stressors. Our results suggest that interannual differences in seasonal zooplankton community succession may be influenced directly by turbidity, cyanobacterial blooms, predatory zooplankton, and invasive crustacean zooplankton, and indirectly by PO4-P availability and temperature. Based on these results, we suggest that two separate management goals alleviating eutrophication and managing the spread of invasive species may be in conflict. We recommend future studies on the competition between native and non-native species to better understand the effects of cyanobacterial blooms on the success of non-native species, and the potential long-term consequences of non-native species invasions on zooplankton community dynamics.