Influence of mixtures of organic pollutants to the phytoplankton gene expression of photosynthesis

Background/Question/Methods . Organic pollutants reach the global oceans through atmospheric transport and deposition, and once these organic pollutants enter the water column they tend to bioaccumulate in phytoplankton. It is now well known that phytoplankton play a key role on the biogeochemical cycles of many organic pollutants. However, it is still not know how organic pollutants, especially the complex mixtures of thousands of organic pollutants present in seawater at ultra trace levels affect phytoplankton populations, and their key ecological function. The present work will show several lines of evidence showing the influence of organic pollutants on the gene expression of photosynthesis by prochlorococcus, and by the general phytoplankton community. In addition, field evidence for the influence of organic polltuants on measured primary productivity and photosynthesis efficiency will also be shown. The work is based on field experiments and field measures performed in the Atlantic, Pacific and Indian Oceans in 2011 within the framework of the Malaspina circumnavigation expedition.

Results/Conclusions . The results obtained from genes codifying the carbon fixation and photosystem II show an effect of mixtures of organic pollutants on the expression of these genes for prochlorococcus, the most abundant photosynthetic organism on Earth. In addition, the meta-transcriptomes from the field experiments also show an effect of the gene expression of phytoplankton and bacterial communities due to mixtures of organic pollutants, only a factor of two higher than the field concentrations. The implications of these results on the potential importance of organic pollution as a vector of global change will be discussed.