Invertebrate Predator Effects on Daphnia and Other Zooplankton Species

Session: 54. - Food Web Ecology and Dynamics of Lake Ontario: Nearshore ? Pelagic Linkages

Gabriella Doud, Cornell University, [email protected]
James Watkins, Cornell University, [email protected]
Brian Weidel, U.S. Geological Survey, Great Lakes Science Center, [email protected]
Lars Rudstam, Cornell University Bio Field Station, Dept. of Natural Resources, [email protected]

Abstract

Two major zooplankton invaders in Lake Ontario, the predatory cladocerans Cercopagis pengoi and Bythotrephes longimanus, have been implicated as drivers of food web disruption, including changes in the zooplankton community structure, in Lake Ontario and elsewhere. We analyzed available data from August surveys from 1997 to 2016 to investigate if changes in crustacean community structure correlate with the abundance of these two predators.  Among observed correlations are strong negative correlations between Cercopagis and Bythotrephes as well as positive correlations between Bythotrephes and calanoid copepods and Daphnia galeata mendotae.  The other major Daphnia species in the lake, Daphnia retrocurva was positively correlated with Cercopagis and negatively correlated with Bythotrephes.  We argue that these community changes are related to the specific behavior of different crustacean species that makes them more or less vulnerable to predatory invertebrates, coupled with the effect of changes in fish zooplanktivory, in particular planktivory by alewife, across this time period. 

1. Keyword
zooplankton

2. Keyword
invasive species

3. Keyword
Cercopagis pengoi

4. Additional Keyword
Alewife

5. Additional Keyword
Daphnia

6. Additional Keyword
Bythotrephes longimanus