Abstract
- Various functional group hypotheses have provided different predictions for the influence of mobile deposit feeders on the composition of marine soft-sediment communities. Two that have received particular attention are the trophic group amensalism and mobility mode hypotheses. Trophic group ammensalism suggests that deposit feeders will primarily affect suspension feeders through resuspension of sediments while a mobility mode approach suggests that sediment disruption is the mechanism of interaction, with sedentary organisms being the group most adversely affected. The macrofauna around a dense intertidal bed of the burrowing ghost shrimp Callianassa californiensis (Dana) was studied to test the predictions of these hypotheses. Most sedentary species, including deposit feeders, had much lower numbers within a dense shrimp bed compared to adjacent areas of low C. californiensis numbers. However, there was no change in faunal richness. These distributions are consistent with a mobility mode of interaction and are in contrast with recent studies of the ghost shrimp's effect on subtidal bivalve populations.