Marine trophic networks in Terra Nova Bay during different ice extent: stable carbon and nitrogen isotopes for determination of trophic interactions affecting biodiversity and heavy metal bioconcentration.

Food chains underlie the mechanisms of coexistence among species, influencing their biodiversity and contaminant accumulation phenomena. Ice dynamics, which in Terra Nova Bay (BTN) is affected by extraordinary seasonality, drives interspecies interactions because in the absence of ice, primary producers are activated that open new pathways of trophic flow among animals. Through stable isotope analysis of C and N, this project will (i) reconstruct the trophic network structure at BTN at different bathymetries and under opposite ice cover conditions, and (ii) assess the accumulation and propagation of trace pollutants along food chains to commercially valuable fish. The hypothesis to be tested is whether activation of primary producers with thaw significantly changes trophic network structure, stability against species loss, and heavy metal concentrations along food chains. There are scarce data on Antarctic trophic networks, and poorer knowledge exists on primary and secondary biodiversity loss and accumulation processes of contaminants and metals in invertebrates and fish. This research will shed light on the processes of biodiversity maintenance in the Antarctic ecosystem and on the risks to human health from accumulated heavy metals in fish fauna targeted by fisheries, also in the perspective of the changing extent of sea ice cover, establishing a baseline for further studies at the Italian Antarctic Station and for the management of the Ross Sea Marine Protected Area.