Ocean currents determine shrimp connectivity

The coherency among larval stages of marine taxa, ocean currents and population connectivity is still subject to discussion. A common view is that organisms with pelagic larval stages have higher dispersal abilities and therefore show a relatively homogeneous population genetic structure.  Contrary to this, local genetic differentiation is assumed for many benthic direct developers.
Specific larval or adult migratory behavior and hydrographic effects may significantly influence distribution patterns, rather than passive drifting abilities alone. The Southern Ocean is an ideal environment to test for the effects of ocean currents on population connectivity as it is characterized by several welldefined and strong isolating current systems. In this study we studied the genetic structure of the decapod deep-sea shrimp Nematocarcinus lanceopes, which has planktotrophic larval stages. We analysed 194 individuals from different sample localities around the Antarctic continent using nine microsatellite markers. Consistent with a previous study based on mitochondrial DNA markers, primarily weak genetic patterns among N. lanceopes populations around the continent were found. Using ocean resistance modeling approaches we were  able to show that subtle genetic differences among populations are more likely explained by ocean currents rather than by geographic distance for the Atlantic Sector of the Southern Ocean.