Latitudinal diversity patterns of deep-sea marine nematodes and organic fluxes: a test from the central equatorial Pacific

The discovery of an apparently positive latitudinal gradient in nematode species richness over a limited geographic area in the North Atlantic, leading to the hypothesis that it is associated with a positive latitudinal organic flux gradient, has created some debate. A test of this hypothesis is that the negative latitudinal organic flux gradient in the central equatorial Pacific should lead to an associated negative gradient in species richness. Here, we show that species richness in the central equatorial Pacific is positively associated with the organic flux predicted from the pattern reported for the North Atlantic. The patterns in nematode species richness differ from other deep-sea organisms; they seem to be entirely related to modern ecology and unaffected by historical events.