Factors shaping microbial community structure and dissolved organic matter composition during austral spring in the San Jorge Gulf

GABRIELA WILIAMS; ANTONELLA DE CIAN; AGNETA ANDERSSON; JOANNA PACZKOWSKA; FLAVIO PAPARAZZO; BRUGEL, SONIA; AUGUSTO C. CRESPI ABRI; JUAN PABLO PISONI; RODRIGO GONÇALVES

Umeå,

Conferencia; Ecochange Conference; 2020

The Patagonian Shelf is one of the most complex region on the Earth, where marine organisms are governed by various physical properties and dynamic processes of the ocean including currents, thermal fronts, up- and downwelling events or freshwater discharge. Marine biological productivity depends on phytoplankton and heterotrophic bacterial interactions, influencing the energy and carbon transfer to higher trophic higher trophic levels including fish, birds and marine mammals. The aim of this project was to study major factors governing the microbial food web under changing mixing conditions in the San Jorge Gulf, the largest basin of the Patagonian Shelf. Additionally, the source and composition of dissolved organic matter (DOM) was studied using absorbance and fluorescence spectroscopy. San José Gulf campaign was carried out during austral spring 2017. Surface water samples were collected for biological and chemical analyses (dissolved inorganic nutrients, colored dissolved organic matter (CDOM) Chlorophyll a (Chl a) and microbial abundances. Moreover, the Simpson-Hunter stratification index was estimated based on CTD data. A clear separation between stratified and well-mixing waters was observed influencing microbial food web structure and CDOM composition.