Climate change effects on phytoplankton from coastal Antarctica: a fatty acid approach

ANTACLI, J.; MALANGA, G.; ANTONI J.; SCHLOSS, I. R.; HERNANDO M.; MENDIOLAR M.; ALMANDOZ G. O.; DE TROCH, M.; VARELA, D.; HERNANDEZ D.

Mar del Plata

Congreso; XVIII Congreso Latino Americano de Ciencias del Mar (COLACMAR); 2019

Marine plankton use different strategies to cope with ocean warming and reducedsalinity from glacial melting (1). We studied these effects on the physiology of naturalphytoplankton assemblages from Potter Cove (25 de Mayo Island, Antarctica) in the2016 summer during 7 days in outdoor microcosms. A 4°C increase in seawatertemperature (T+) and a 4 psu decrease in salinity (S-) from ambient values were studiedusing the following treatments: control (S0T0), S-T0, S0T+, and S-T+. Changes in fatty acidand particulate carbon content (C), and the balance between lipid damage and lipidsoluble antioxidants (α-tocopherol) were analyzed. Saturated fatty acid (SFA)concentrations were higher than polyunsaturated (PUFA) and monounsaturated(MUFA) FAs in all treatments. However, a significant increase in the unsaturated(UFA)/SFA ratio was observed on day 3 in S0T+. A significant increase in lipid damagewas measured under S-T+ but only on day 1, and it decreased when α-tocopherolconcentrations increased, which resulted in C biomass accumulation under T+. Naturalphytoplankton assemblages were dominated by the sub-Antarctic diatoms Chaetocerosand Shionodiscus. Noteworthy, under S-T0, with constant lipid damage due to stress,small phytoflagellates became dominant at the end of the experiment, contrasting withthe sub-Antarctic diatoms still dominating in other treatments. This study suggests thatalthough sub-Antarctic species are adapted to T+ conditions, they are still affected bysalinity stress, which they partially compensate by adjusting lipid composition andincreasing α-tocopherol production.