We examined the possibility that a non-native oyster species would provide an
ecologically-functional equivalent of the native oyster species if introduced into the
Chesapeake Bay. Habitat complexity and associated benthic communities of
experimental triploid Crassostrea virginica and C. ariakensis reefs were investigated at
four sites of varying salinity, tidal regime, water depth, predation intensity, and disease
pressure in the Chesapeake Bay region (Maryland and Virginia). Four experimental
treatments were established at each site: C. virginica; C. ariakensis; 50:50 of C.
virginica: C. ariakensis; and shell only. Abundance, biomass, species richness, evenness,
dominance and diversity of reef-associated fauna were evaluated in relation to habitat
location and oyster species. Although habitat complexity varied with location, no
differences among complexity were associated with oyster species. Similarly, differences
in faunal assemblages were more pronounced between sites than within sites. Our results
show functional equivalency between oyster species with respect to habitat at the
intertidal site and the low salinity, subtidal location. At subtidal sites of higher salinity,
however, the numbers of organisms associated with C. virginica reefs per unit of oyster
biomass were significantly greater than the numbers of organisms associated with C.
ariakensis reefs. Multivariate analyses of data from subtidal high salinity sites revealed
unique communities associated with C. virginica treatments, while mixed oyster species
assemblages were functionally equivalent to mono-specific C. ariakensis experimental
treatments. Our study represents the first effort to quantify the potential habitat function
of C. ariakensis, which has been proposed for an intentional introduction into