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

FLAVIO PAPARAZZO; REGINA PIERATTINI; RODRIGO GONÇALVES; AUGUSTO CÉSAR CRESPI ABRIL; GABRIELA N. WILLIAMS; AGNETA ANDERSSON; JOANNA PACKOWSKA; ANTONELLA DE CIAN; SONIA BRUGEL

Mar de Plata

Congreso; XVIII Congreso Latinoamericano de Ciencias del Mar-COLACMAR 2019; 2019

Interaction between phytoplankton and bacteria is one of the most important relationship in aquatic ecosystems, shaping carbon and nutrients cycling and regulating biological productivity. Phytoplankton are the major primary producers responsible for almost half of global net primary production supporting over 95% of marine food web.During photosynthesis, phytoplankton convert atmospheric carbon dioxide (CO2) into organic matter (OM) in the presence of sunlight and dissolved inorganic nutrients.Bacteria as heterotrophs obtains essential carbon for growth by consuming labile organic carbon released by the phytoplankton (autochthonous) or deliver from external sources (allochthonous) via rivers, groundwater or atmospheric deposition.Phytoplankton-produced organic matter contains mainly low-molecular-weight (LMW) compounds such as amino acids, simple sugars which can be directly assimilated by heterotrophic bacteria, while allochthonous organic matter is characterized by higher contribution of high-molecular-weight (HMW) e.g. proteins which need to be transformed to more simple molecular through various enzymatic and abiOtic (e.g., photolysis) processes. The aim of this project was to study factors governing microbial community structure and examine the source and composition of the dissolved organic matter in the San Jorge Gulf using absorbance and fluorescence spectroscopy. Samples were collected during Pampa Azul campaign in October/November 2017.