Ice dynamics and variations in trophic networks and transfer of contaminants at Terra Nova bay: a study based on the analysis of stable isotopes (C, N) and heavy metals in sympagic algae, plankton, fish and avifauna

Trophic interactions underlie coexistence mechanisms between species, define the functional role of specie within communities, affect biodiversity and bioaccumulation processes of heavy metal. Sea-ice dynamics, which at Terra Nova Bay is characterized by an extraordinary seasonality, drives interspecific interactions and the exchange of materials between ecosystem compartments. Indeed, the activation of the primary production after sea-ice break up opens alternative trophic pathways for consumers. The “next generation SRPs” represent a highly appropriate framework for the present project which follows the results obtained with the previous project ISOBIOTOX (PNRA 2013) and aims at (i) determine topological and functional metrics of sympagic and pelagic food webs at Terra Nova Bay under different conditions of sea-ice coverage along a distance gradient from the nearest open water polynya to areas were the seasonal sea-ice coverage persists longer; (ii) evaluate bioaccumulation and biomagnification of heavy metals in trophic sources at the base of the food web and in target species along food chains, including fishes of commercial interests and top predators, both in the presence and absence of sympagic and pelagic primary producers. High resolution food webs will be reconstructed by means of the simultaneous elemental and isotopic analysis of different elements (C and N) and the bioaccumulation of pollutants. The research program integrates complementary research approaches: (a) Elemental analysis coupled with mass spectrometry for stable isotope analysis (δ13C, δ15N) in animal and vegetal tissues and dead organic matter, (b)analyses of heavy metals accumulation (Chromatography) in the constituent species of the Antarctic food web.