Macrofauna using intertidal oyster reef varies in relation to position within the estuarine habitat mosaic

Abstract

Oyster reefs are important components of marine ecosystems and function as essential habitat for estuarine species; however, few studies have simultaneously compared natural intertidal reefs to more well-studied seagrass meadows and marsh habitats. We investigated habitat use within an estuarine mosaic consisting of intertidal oyster reef (Crassostrea virginica), seagrass (Halodule wrightii), and marsh edge (Spartina alterniflora) habitats in Corpus Christi Bay, Texas. Oyster sampling units (OSUs) were deployed within intertidal oyster reef, and modified throw traps were used to collect macrofauna inhabiting the OSU and other adjacent vegetated habitats. Habitat arrangement and proximity as it relates to macrofaunal density, species richness, and community composition were also evaluated by comparing communities in oyster reef within the oyster reef complex, oyster reef adjacent to a seagrass complex, and oyster reef adjacent to marsh edge. Higher macrofaunal densities and species richness were observed within oyster reefs compared to seagrass and marsh edge. Oyster reef also supported a distinct community, while seagrass and marsh shared similar species composition and richness. The highest densities of macrofauna were collected on oyster reefs near seagrass and oyster reef located within the oyster reef complex. These results indicate the importance of intertidal oyster reefs to macrofauna and that reef location within the estuarine mosaic influences density and community assemblages. These findings are important because in many areas there are large efforts to restore oyster reef in estuarine systems, and for these programs to be successful, it is necessary to understand the functional roles and linkages among habitats.