The effects of boring sponge on oyster soft tissue, shell integrity, and predator-related mortality.

摘要

Parasitism (including bioeroders of living bivalve shells) may modify optimal foraging models by altering the relationship between energy exerted and reward gained in acquiring prey resources. Boring sponges of the family Cliona burrow into calcareous material, including the shells of the Eastern Oyster Crassostrea virginica, and create extensive tunnels and galleries. To consider the effects of boring sponge infestation on predator-prey interactions, I calculated the reward/effort ratio of infested and healthy oysters using dry tissue mass (generally unaffected by sponge infestation) and crushing force (generally lower for sponge-infested oysters). These data suggest that crab predators should attack larger, heavily infested individuals. However, two types of feeding trials did not yield a clear pattern of crab prey preference for sponge-infested oysters. A preference may not have been observed because stone crabs are opportunistic predators with very strong chelipeds. Conversely, the relationship between boring sponge, oysters, and oyster predators may be convoluted.