Prokaryotic activity and diversity associated to particles in the NW Mediterranean

ENCARNA BORRULL; EVA ORTEGA-RETUERTA; MARIA MONTSERRAT SALA; PERE PUIG; CAROLINA ANTEQUERA ; CELIA MARRASE; FRAN APARICIO-BERNAT; HANS-PETER GROSSART; SUSANA SÁNCHEZ-DEL RÍO ; ANDREA MALITS; JOSEP M. GASOL

Congreso; Planeta Oceà - XXXII Trobades científiques de la Mediterrània ? Josep Miquel Vidal; 2016

The decomposition of particulate matter has always been considered one of the major pathways in the recycling of nutrients in the oceans. Organic particles may constitute a niche for prokaryotes that may harbor specific bacterial communities different to those in the surrounding water and a hot-spot of bacterial activity.We investigated prokaryotic abundance, diversity, production and extracellular enzyme activities together with particle concentration in a cruise from the coast to the open ocean in the NW Mediterranean. Our results showed decreasing prokaryotic activity and extracellular enzyme activities with depth. However in layers of increased turbidity, i.e. bottom nepheloid layers (BNL), increased chitinolytic activity and lower proteolytic activity was found, suggesting that prokaryotes in nepheloid layers rely more on chitin than proteins for C and N acquisition.In terms of diversity, the composition of the free-living prokaryotic community of the deepest station (2300m) was similar between the nepheloid layer and bathypelagic waters. However, the attached prokaryotic community differed considerably. Specifically, Archaea contributed a higher percentage (12.6%) to the attached community in nepheloid layers than in bathypelagic waters (5.2%).