CS17 Invasive Species
Date: Thursday, June 13, 2002
Time: 2:15:00 PM
Location: Sidney
 
JohannssonOE, Fisheries and Oceans, Burlington, Canada, johannssono@dfo-mpo.gc.ca
 
IMPACT OF EXOTICS ON SPATIAL AND TEMPORAL PATTERNS OF ENERGY FLOW IN THE LAURENTIAN GREAT LAKES
image
By the 1970s, the lower Great Lakes had become dominantly, pelagic- driven systems. The benthic regions started to improve and pelagic productivity to decrease with the declines in phosphorus and contaminant loadings in the 1970s and 80s. The invasion by dreissenid mussels in 1988 rapidly encouraged further transfer of productivity through the benthic systems. Zooplankton production in nearshore, high-dreissenid regions of Lake Erie was 50%-80% lower than expected, given the phosphorus concentrations. Plankton were protected to a large extent in the offshore by thermal stratification. Zooplankton community structure has changed in both the offshore and nearshore with the arrival of Bythotrephes and Cercopagis, two predatory cladocerans. They undoubtedly compete for prey with Mysis relicta, an important component of the diet of many offshore fish. With the arrival of these exotic species, the seasonal and vertical availability of prey for fish has been altered.