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Production and composition of dissolved organic matter in the ocean - importance of the ecological interactions in the plankton


Research objectives and content
The production of dissolved organic carbon (DOC) in the euphotic ocean and its accumulation in the upper mixed layer gives way to a downward carbon (C) flux whose magnitude in terms of potential atmospheric CO2 sequestration is comparable to that of sinking particulate organic C. However, the efficiency of the DOC pump as a C export mechanism depends on the biodegradability of the dissolved organic matter, which in turn is a function of its composition. In the present project, we will determine the production rate, aminoacid to carbohydrate ratio and size structure of dissolved organic matter as a function of phytoplankton physiological state and zooplankton grazing activity. In addition, we aim to quantify the effects of DOC composition upon bacterial production and growth, as this is the critical step governing the fate of recently produced dissolved organic matter. In order to achieve these objectives, we suggest a combined approach where observational and experimental studies will be carried out both in the laboratory using natural plankton assemblages and in situ during a cruise to the eastern North Atlantic subtropical gyre. The ultimate output of the project will be a quantitative, sea-validated assessment of the way in which the ecological interactions within the plankton control the quantity, quality and fate of newly produced DOC. Training content (objective, benefit and expected impact)
The work programme will look at the ecological interactions between different compartments of the pelagic ecosystem, rather than focusing on a single group of organisms. This cross-trophic level approach is essential for the understanding of biologically-mediated carbon cycling in the oceans. The multi-disciplinary nature of the project will ensure the applicant's training through the use of new experimental techniques and the interaction with other members of the EU-funded CANIGO (Canary Islands Azores Gibraltar Observations) project, some of whose objectives will be complemented by the research activities included in the present proposal. Links with industry / industrial relevance (22)

Funding Scheme

RGI - Research grants (individual fellowships)


Campus Lagoas-marcosende
36200 Vigo