UTILITY OF MARINE BENTHIC ASSOCIATIONS AS A MULTIVARIATE PROXY OF PALEO-BATHYMETRY: A DIRECT TEST FROM RECENT COASTAL ECOSYSTEMS OF NORTH CAROLINA

Marine benthic associations from present-day habitats can not only provide quantitative insights into community ecology and conservation biology, but also aid in assessing and developing paleoecological and paleoenvironmental proxies applicable to the fossil record. Systematic quantitative sampling of the live marine benthos in coastal North Carolina was conducted to evaluate macro-faunal associations along an onshore-offshore gradient and determine their informative value as paleo-bathymetric indicators.

Multivariate ordinations were used to determine whether modern benthic marine invertebrate communities can be effectively used to extrapolate bathymetry. Samples were analyzed using detrended correspondence analysis (DCA). The DC1 scores of samples correlate tightly with the actual depth values of the samples, confirming that samples ordinate along an axis that primarily reflects bathymetry and its environmental correlatives. Moreover, when the DC1 scores are calibrated with modern ecological data, the resulting estimates of sample depths are a robust proxy of their actual bathymetry.

In coastal ecosystems of North Carolina, bathymetry appears to be a primary controlling factor, with faunal assemblages changing predictably in terms of their taxonomic composition with depth. This relation is remarkable also because coastal habitat variation and anthropogenic effects may act as confounding factors here, particularly in inlets, harbors, and estuarine settings.

Although it is arguable that individual case studies such as this one can support broader generalizations, these results are promising and consistent with multiple paleontological studies. Fossil communities may provide robust quantitative estimates of bathymetry with potential applications to paleoecology and stratigraphy.