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Highest marine species richness is found in tropical coastal areas

Costello & Chaudhary (2017) used data from OBIS to show that marine species richness is higher in the coastal tropics and decreases with depth. The paper reviews what factors have led to species diversification, and how this knowledge informs conservation priorities.

Two representations of species richness were compared to sea surface temperature and productivity. To minimise sampling effort bias, Estimated Species richness (ES50) was calculated as the number of species in 50 random samples from each 5 degree latitude-longitude cell derived from a dataset of 65,000 species distributions from OBIS in 2009 and equal area hexagons from 51,670 species from OBIS in 2015.

Four measures of species richness calculated from the above hexagons, and sea temperature, were plotted with depth. Species richness, calculated for 32,328 species with known depth of occurrence, for 50,000 km2 hexagrids in the depth range 0 – 500 m (interval of 100) and 500 – 9,000 m (interval of 500).

For environmental data see http://gmed.auckland.ac.nz/.

Details in: Costello MJ, Chaudhary C. 2017. Marine biodiversity, biogeography, deep-sea gradients, and conservation. Current Biology 27, R511–R527. http://dx.doi.org/10.1016/j.cub.2017.04.060