CS17 Invasive Species
Date: Thursday, June 13, 2002
Time: 11:45:00 AM
Location: Sidney
 
ReedT, University of Wisconsin - Green Bay, Green Bay, WI, USA, reedandt@uwgb.edu
Wielgus, S, J, University of Wisconsin - Green Bay, Green Bay, WI, USA, 
Barnes, A, K, University of Wisconsin - Green Bay, Green Bay, WI, USA, 
Schiefelbein, J, J, University of Wisconsin - Green Bay, Green Bay, WI, USA, 
Fettes, A, L, Integrated Paper Services, Appleton, WI, USA, 
 
IMPACT OF ZEBRA MUSSELS (DREISSENA POLYMORPHA) ON BENTHIC INVERTEBRATE ABUNDANCE AND DISTRIBUTION IN LOWER GREEN BAY, LAKE MICHIGAN
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We use a field survey and lab experiments to examine the effect of Dreissena density on the diversity and distribution of benthic invertebrates in Green Bay and to explore the hypothesis that benthic invertebrate abundance increases following Dreissena invasion because the complex habitat provided by Dreissena druses (clusters) offers refugia from predation. We surveyed macroinvertebrates in Dreissena druses and adjacent sediment samples at ten sites in lower Green Bay. While sediment invertebrate density and Dreissena density were correlated (r = 0.8), the mean invertebrate density in the druses (2.3 invertebrates cm-3) was significantly higher than in the adjacent sediment (0.06 invertebrates cm-3). Amphipods were the most abundant taxa. Other taxa included leeches, hydra, mayflies and caddisflies. In lab trials with various predators (perch, round goby and rusty crayfish) at least 75% of the amphipods escaped predation where Dreissena were present. Without mussels amphipods escaped predation only in the crayfish treatment. We postulate that increased abundance of macroinvertebrates in the lower bay is due to increased refugia and further that the spatial distribution of invertebrate taxa is driven by local conditions.