Is deep-sea species diversity really so high? Species diversity of the Norwegian continental shelf

Abstract

Sanders (1968; Am. Nat. 102: 243-281) showed that, contrary to general opinion at the time, the deep-sea had high species diversity when compared with estuarine and coastal areas. This paper stimulated a series of studies and theoretical arguments aimed at explaining why the deep-sea had such high diversity. It is now accepted that the deep-sea has high diversity and it has been suggested that in the deepsea there may be up to 10 million new species yet to be described (Grassle & Maciolek 1992; Am. Nat. 139: 313-341). Surprisingly, however, there have not been any recent comparisons between the fauna of the deep-sea and shallower areas. Here I present data from a survey taken from the continental shelf of Norway which allows a quantitative comparison to be made with recent data from the deep-sea. Species diversity is very similar to that of the deep-sea and speciesarea curves have almost identical slopes. These data suggest that the Norwegian continental shelf has species diversity equal to that of the deep-sea and thus leads one to question the paradigm that the deep-sea has exceptionally high diversity.