The effect of dust on phytoplankton communities of Nuevo Gulf

DE CIAN, ANTONELLA; CRESPI-ABRIL, AUGUSTO; BARBIERI, ELENA; PACZKOWSKA, J; B|RUGEL, S; ANDERSON, A; SORIA, GASPAR; HERNANDEZ-MORESINO, R; PAPARAZZO, F; BARKI, LOURDES; EPHERRA, L; MARTELLI, A; GETINO MAMET, LEANDRO NICOLÁS; GONCALVEZ, R.

Bremen

Congreso; International Conference for YOUNG Marine Researcher, ICYMARE; 2019

University of Bremen, Germany

Atmospheric dust is a source of micro-and macronutrients to the ocean and plays an important role in shaping marine biogeochemical cycles and possibly in global climate by promoting CO2sequestration. Despite Patagonia being the major source of aeolian dust in the southern part of the Atlantic Ocean, responses of plankton communities to dust input have not yet been studied. The aim of our study is to determine the effect of Patagonian dust on coastal phytoplankton communities in field and experimental studies. Biweekly sampling was performed at a fixed station located in front of Puerto Madryncity in Nuevo Gulf to study the dynamics of phytoplankton communities influenced by atmospheric and oceanographic conditions of this coastal system. Additionally, a microcosm incubation was carried out in situ next to the sampling station during the summer period. The aim of the experiment was to determine the response of a natural phytoplankton community to the addition of dust collected during spring of 2018. It was run for 5 days with three treatments (in triplicates): control (without dust addition), low dust concentration (DustL, 0.2 mg/L) and high dust concentration (DustH, 1 mg/L). Changes in variables of nutrients (dissolved inorganic phosphorus, dissolved inorganic nitrogen and silicate), chlorophyll a and dissolved organic carbon (DOC) were measured over time. As preliminary results, highest concentrations of nitrate+nitriteand DOC were found in DustHtreatment, while DustLtreatment did not significantly differ from the control. DustLshowed higher concentrations of chlorophyll athan DustHand the control treatment. As a brief discussion we estimate that atmospheric Patagonian dust adds dissolved macronutrients to the seawater, and there may be other processes as toxicity or grazing that could be negatively affecting the physiology of the phytoplankton community.