Characterization of dissolved organic matter and distribution of microbial food web in the San Jorge Gulf

JOANNA M. PACZKOWSKA; SONIA BRUGEL; ANTONELLA DE CIAN; AUGUSTO C. CRESPI-ABRIL; GABRIELA N. WILLIAMS; REGINA PIERATTINI MARTÍNEZ; FLAVIO E. PAPARAZZO; AGNETA ANDERSSON; RODRIGO J. GONÇALVES

Puerto Madryn (Chubut, Argentina)

Workshop; V Seminario Golfo San Jorge: avances y retos futuros; 2018

CCT CONICET-CENPAT

Dissolved organic matter (DOM) is a complex mixture of carbon,-nitrogen, - phosphorus- and sulfur-rich compounds in the ocean (DOC,DON, DOP and DOS). Carbon constitutes ~ 60% of DOM that is why DOM isoften referred as DOC (1). Phytoplankton is a major source of DOM inthe ocean (autochthonous Au_DOM) while in coastal areas DOMoriginated from leaf and roots exudates, litter leakages andmetabolites released by different soil organisms can dominate DOMpool (allochthonous Al_DOM) (2). Besides exudation by growing anddead phytoplankton cells, other processes are important sources ofDOM in the ocean: mesozooplankton sloppy feeding, excretion (bymesozooplankton and microbial heterotrophic plankton), leakage fromsinking faecal pallets and viral lysis of bacteria (Fig.1- Au_DOM,Al_DOM) (3). Au_DOM contains mainly labile, low-molecular-weight(LMW) compounds such as amino acids, simple sugars which can bedirectly assimilated by heterotrophic bacteria. Al_DOM is dominatedby recalcitrant, high-molecular-weight (HMW) compounds e.g. proteinswhich need to be transformed to more simple molecular through variousenzymatic and abiotic (e.g. photolysis) processes. DOM plays animportant role in shaping the microbial food web due totransportation of carbon, nutrients, trace metals e.g. iron formicroorganisms. Furthermore, DOM influences light conditions forphytoplankton especially in coastal areas (4).p { margin-bottom: 0.25cm; line-height: 115%; background: transparent none repeat scroll 0% 0%; }