CS17 Invasive Species
Date: Thursday, June 13, 2002
Time: 3:15:00 PM
Location: Sidney
 
DudasSE, University of Victoria, Victoria, Canada, sdudas@uvic.ca
McGaw, I, J, University of Nevada Las Vegas, Las Vegas, USA, imcgaw@ccmail.nevada.edu
Dower, J, F, University of Victoria, Victoria, Canada, dower@uvic.ca
 
SELECTIVE CRAB PREDATION ON NATIVE AND INTRODUCED BIVALVES IN BRITISH COLUMBIA
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Experiments were conducted to determine if Cancer crab spp. prefer native littleneck (Protothaca spp.) bivalves to a recently introduced species from Japan, the varnish clam (Nuttallia obscurata). Prey preference, handling time and consumption rates were investigated for both clam species. Results indicate that the introduced species is preferred over the native species. This is likely due to the lower handling time the crabs required to consume the varnish clam, due to its thinner shell. Both the native and introduced bivalves burrow into the substrate, with N. obscurata occurring at greater depths. To investigate burial depth as a refuge from predation, equal numbers of each bivalve species were allowed to bury in the substrate and were then exposed to crab predation. Preliminary findings suggest that although the varnish clam is preferred, it is not as accessible as the littleneck clam. Results will be discussed in relation to the potential impact of this invader, on the ecological interactions of intertidal communities.