Dra. Alice Della Penna

 

This seminary is about pelagic organisms live and interact with each other in a highly dynamic environment which is structured by oceanographic features at multiple scales. Mesoscale eddies (rotating currents with lifetimes of few weeks-few months) have been observed to strongly impact the distribution of primary production in the ocean. At the other end of marine foodwebs, a growing number of animal tracking studies suggest that apex predators, from seabirds to sharks and marine mammals, tend to collocate with mesoscale eddies. Yet, the mechanisms behind this close relationship are not well understood. In this presentation, I will discuss some recent work that aims at understanding how mesoscale eddies affect the distribution of micronekton, a diverse group of animals ranging from small squids, fishes and crustacea, which are common prey items for pelagic predators. Using sonar acoustics as a proxy for the distribution of these organisms, I will show how we found a strong relationship between eddy properties and the distribution of micronekton, from the ocean surface to the mesopelagic ocean (200-1000 m deep) and from the North Atlantic to the Southern Ocean. These results can help explain why apex predators collocate with mesoscale eddies and what role oceanographic features play in structuring the distribution of micronekton worldwide.