MOLLUSKS AS ARCHIVES OF SPATIAL BIODIVERSITY PATTERNS IN MARINE BENTHIC COMMUNITIES: AN EXAMPLE FROM COASTAL NORTH CAROLINA, USA

Rigorous documentation of spatial heterogeneity (beta diversity) in present-day and preindustrial ecosystems is required to assess how marine communities respond to environmental and anthropogenic drivers. However, the overwhelming majority of contemporary and paleontological assessments have centered on single higher taxa. To evaluate the validity of single taxa as community surrogates and paleontological proxies, we compared macrobenthic communities and sympatric death assemblages at 51 localities in Onslow Bay (North Carolina, USA). Compositional heterogeneity did not differ significantly across datasets based on live mollusks, live non-mollusks, and all live organisms. Datasets based on death assemblages were less heterogeneous spatially, likely reflecting homogenization induced by time-averaging. Nevertheless, live and dead datasets were >80% concordant in pairwise comparisons to literature estimates of beta diversity in other marine ecosystems, yielded concordant bathymetric gradients, and produced nearly identical ordinations consistently delineating habitats. Congruent estimates from mollusks and non-mollusks suggests that single groups can serve as reliable community proxies. The high spatial fidelity of death assemblages supports the emerging paradigm of Conservation Paleobiology. Integrated analyses of ecological and paleontological data based on surrogate taxa can quantify anthropogenic changes in marine ecosystems and advance our understanding of spatial and temporal aspects of biodiversity.