Global Diversity of Mesopelagic Mesozooplankton

Despite the ecological importance of mesozooplankton, little is known about their global distribution and diversity in the mesopelagic realm. This study examines the spatial distribution and diversity of 861 mesozooplankton species using species distribution models. The highest species richness and range-size rarity were found in the offshore North Atlantic and coastal areas across both hemispheres, while the Pacific and Indian ocean basins had low rarity and species richness. Latitudinal species richness peaks around 30° N and 30° S, with hotspots mainly within 40°S and 40°N, absent in polar areas. However, mean species richness per area is higher and more evenly distributed in polar regions compared to equatorial or tropical areas. The study also found a correlation between water temperature and species richness, with the highest richness at around 25°C, decreasing sharply below ~10°C.