Modern and Interglacial Marine Ostracode Species Diversity Patterns off Eastern North America

Abstract

Latitudinal species diversity gradients (LSDGs) are a major feature of various marine groups. However, the detailed shape of LSDG in each marine taxonomic group and the causes of the diversity patterns, notably climatic factors, are still controversial due to limited sampling of many taxa in the world’s oceans. We analyzed benthic podocopid ostracode faunal assemblages on the continental shelf regions from Arctic to tropical regions off eastern North America to determine biodiversity patterns and their relationships to oceanographic conditions (temperature, productivity, etc). Our database consists of 200 ostracode species from more than 100 bottom sediment samples. Preliminary results suggest that biodiversity, as measured using simple diversity (S), rarefaction, Shannon and α-Fisher indices, show strong latitudinal diversity gradients in which diversity is 2 to 3 times higher in tropical and subtropical regions that in northern high latitude areas. These modern ostracode diversity patterns will be compared with those from past interglacial periods of global warmth during the Pliocene and Pleistocene to assess the impact of warmer-than- present climate conditions on diversity.