Meeting Abstract
P2.85 Monday, Jan. 5 The role of shifting detection thresholds and associative learning determine prey responses to the European green crab on the west coast of North America NEUFELD, Chris J.*; EDGELL, Tim C.; University of Alberta; University of Alberta chris.neufeld@ualberta.ca
Rapid population-wide changes in the ability of prey to detect novel predators are common in marine systems. Many authors conclude that these changes have resulted from rapid evolution of chemical cue recognition. However, an alternative hypothesis – that changes in cue recognition result from within-individual plasticity, mediated by cue sensitivity or associative learning – has not been tested. In the northeast Pacific, the recent arrival of the European green crab, Carcinus maenas, offers an opportunity to study the mechanisms used by prey to recognize and respond to novel predators. On the Pacific coast, the intertidal whelk Nucella lamellosa thickens its shell when exposed to effluent of the crab Cancer productus or damaged conspecifics; however when native whelks are exposed to the effluent of the introduced European green crab, no shell-thickening occurs. To investigate the role of within-individual changes in cue recognition, whelks were conditioned through exposure to water containing chemical cues from either the novel C. maenas or the familiar C. productus feeding on damaged conspecifics; control groups were exposed to effluent of C. maenas, C. productus, or seawater alone. This phase was followed by a one-month phase where whelks were exposed to effluent of C. maenas or C. productus alone. Whelks exposed to effluent of both the novel and familiar crab predator feeding on conspecifics grew more predator-resistant shells relative to controls when subsequently exposed to effluent from C. maenas. This suggests that shifting detection thresholds or increased fearfulness to novel stimuli may mediate whelk responses to novel predators. These types of responses have the potential to act on entire populations and thus may play a crucial role following the arrival of a novel predator.
