The influence of mesoscale eddies on pelagic predators

Mesoscale eddies and current meanders make up the internal weather of the ocean, exciting vertical fluxes and transporting pelagic communities thousands of kilometers. These ubiquitous features cover ~30% of the open ocean yet their influence on pelagic predators remains largely unknown. By combining movement data collected by more than 300 tagged sharks of 5 different species with ocean observations made by a constellation of satellites and data-assimilating ocean models, we collocated shark positions to mesoscale eddies to quantify how sharks interact with these energetic features in the Atlantic Ocean.

Of particular interest is our comparison of eddy use by endo- and ectothermic sharks across a range of oceanographic regimes with varying eddy energy. The life history differences among shark taxa primarily provide thermoregulatory constraints on species’ habitat use and structure how individuals are able to leverage deep ocean prey resources. Our results challenge the existing paradigm that anticyclonic eddies are generally unproductive, ocean "deserts" and suggest that their warm temperature anomalies at depth may facilitate connectivity between the epipelagic and the ocean twilight zone. This study also provides valuable new insight into open ocean habitat use by pelagic predators and how mesoscale eddies and meanders structure pelagic ecosystems. We propose that observations of mesoscale features should be incorporated into dynamic ocean management approaches. Furthermore, our results shed new light on the ecosystem value of mesopelagic prey, suggesting additional considerations are necessary before biomass extraction from the ocean’s twilight zone as these activities could interrupt a key link between planktonic production and top predators.