Re-evaluation of species diversity patterns of free-living marine nematodes

Abstract

Nematode species diversity was analysed for 55 data points ranging from local studies to large-scale faunal surveys. Multiple regression analysis uses latitude, investigated area, sampling effort and depth as independent variables. Species diversity in a biotope (or α-diversity) is about twice as high in the deep sea, while the main source of diversity in shallow waters is heterogeneity of biotopes (β-diversity). For sites deeper than 100 m, regional species richness shows a unimodal (hump-shaped) latitudinal pattern, with the highest diversity at 30° to 60°N. Species diversity in shallow waters does not show any prominent gradients throughout the world ocean. These patterns possibly reflect the diversity-productivity relationships. Different approaches to estimation of species diversity are discussed.