Environmental controls on the geographic distribution of zooplankton diversity

Proposed explanations for the geographic distribution of zooplankton divers ity include control of diversity by geographic variation in: physical and c hemical properties of the near-surface ocean(1-3); the surface area of biot ic provinces(4); energy availability(5); rates of evolution and extinction( 6); and primary productivity(7). None of these explanations has been quanti tatively tested on a basin-wide scale. Here we used assemblages of planktic foraminifera from surface sediments to test these hypotheses. Our analysis shows that sea-surface temperature measured by satellites explains nearly 90% of the geographic variation in planktic foraminiferal diversity through out the Atlantic Ocean. Temperatures at depths of 50, 100 and 150 m (ref. 9 ) are highly correlated to sea-surface temperature and explain the diversit y pattern nearly as well. These findings indicate that geographic variation in zooplankton diversity may be directly controlled by the physical struct ure of the near-surface ocean. Furthermore, our results Show that planktic foraminiferal diversity does not strictly adhere to the model of continuall y decreasing diversity from equator to pole. Instead, planktic foraminifera l diversity peaks in the middle latitudes in all oceans.