Large-scale ocean connectivity and planktonic body size

Global patterns of planktonic diversity are mainly determined by the dispersal of propagules with ocean currents. However, the role that abundance and body size plays in determining spatial patterns of diversity remains unclear. Here, we analyze spatial community structure - beta-diversity - for several planktonic and nektonic organisms spanning from prokaryotes to small mesopelagic fishes collected during the Malaspina 2010 Expedition. beta-diversity were compared to surface ocean transit times derived from a global circulation model, revealing a significant negative relationship that is stronger than environmental differences. Estimated dispersal scales for different groups show a negative correlation with body-size, where less abundant large-bodied communities have significantly shorter dispersal scales and larger spatial species-turnover rates than more abundant small-bodied plankton. Our results confirm that the dispersal scale of planktonic and micro-nektonic organisms is determined by local abundance, which scales with body size, ultimately setting global spatial patterns of diversity.