Increased Particle Abundance is Associated with Higher Bacterial Activity in Deep Layers?

Maria Montserrat Sala1, Encarna Borrull2, Mireia Mestre2, Susana Sánchez-Del Río2, Carolina Antequera2, Eva Ortega-Retuerta2, Andrea Malits3, Francisco L Aparicio2, Pere Puig2, Josep Gasol2, Hans-Peter Grossart4 and Cèlia Marrasé1, (1)Institut de Ciències del Mar, CSIC, Barcelona, Spain, (2)Institut de Ciències del Mar-CMIMA (CSIC), Barcelona, Spain, (3)Centro Austral de Investigaciones Científicas (CADIC-CONICET), V9410CAB Ushuaia, Argentina, (4)Leibniz-Institute of Freshwater Ecology and Inland Fisheries (IGB), Dep. 3, Experimental Limnology, Stechlin/OT Neuglobsow, Germany
Abstract:
We investigated the abundance, diversity, production and extracellular enzyme activities of bacteria during the cruise NEMO, that covered a transect from the coast to the open sea, an area between Barcelona and Mallorca Island in the NW Mediterranean. We sampled in 8 stations and at up to 8 depths, from the surface to 2300m.

Bacterial activity showed a decreasing pattern with depth. During the cruise, several bottom nepheloid layers, i.e. clouds of particles, were sampled. Although nepheloid layers have been associated with increased bacterial activities, we did not detect a clear increase of bacterial activities. One of the possible causes for this lack of stimulation of the bacterial community might be the minor enrichment in particulate organic carbon in those bottom nepheloid layers.

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