Changes in a benthic community associated with dense beds of a burrowing deposit feeder, Callianassa californiensis

Various functional group hypotheses have provided different prehctions for the influence of mobile deposit feeders on the composition of marine soft-sediment communities.Two that have received particular attenhon are the trophic group amensalism and mobhty mode hypotheses.Trophic group amensalism suggests that deposit feeders will primarily affect suspension feeders through resuspension of sediments while a rnobhty 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 shnmp Callianassa californiensis (Dana) was studied to test the predictions of these hypotheses.Most sedentary species, including deposit feeders, had much lower numbers withm a dense shrimp bed compared to adjacent areas of low C. cahforniensis numbers.However, there was no change in fauna1 richness.These distributions are consistent with a mobihty mode of interaction and are in contrast with recent studies of the ghost shrimp's effect on subtidal bivalve populations.