Oyster-Sponge Interactions and Bioerosion of Reef-Building Substrate Materials: Implications for Oyster Restoration

Abstract

ABSTRACT Subtidal oyster (Crassostrea virginica) reefs constructed during in the mid 1990s in Pamlico Sound, North Carolina, initially supported high densities of oysters; however, beginning around 2007, oyster density subsequently declined. Concurrent with the decline in oyster density was an increase in the prevalence of boring sponges (Cliona) on oysters and the underlying reef substrate material at these sites. The limestone marl substrate used to build these reefs became colonized by boring sponge to the degree that bioerosion by sponge potentially compromised the suitability of the reefs for oysters. Laboratory and field experiments were conducted to determine whether oyster demographic rates of settlement, recruitment, growth, and mortality were affected by the presence of Cliona on underlying shell substrate. Oyster settlement on shells with varying levels of sponge was measured in the laboratory, and oyster recruitment, growth, and mortality in the presence and absence of sponge were measured in ...