Combined effects of environmental factors on phytoplankton physiology

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Pollution caused by pesticides and metals is an actual problem for many aquatic ecosystems. Phytoplankton (algae and cyanobacteria) found in these waters are the first organisms of the food web and may, unfortunately, be very sensitive to water quality variations. Lakes and rivers are impacted rarely by only one pollutant and the toxicity of these chemicals may be affected by other environmental factors, such as light, water temperature and other substances. Very few studies were performed in the past to understand the combined effect of these environmental stressors on the physiology of algae and cyanobacteria. In this research program we will study the effects of cadmium and some pesticides (glyphosate, fomesafen, diazinon and captane) when combined together or to other environmental factors (temperature and light) on phytoplankton physiology. We will focus on the impacts that these environmental factors have on photosystem II - photosystem I electron transport and alternative electron pathways (e.g. cyclic electron flow). We will also study the mechanisms involved in the resistance of phytoplankton species to the combination of environmental factors (e.g. the non-photochemical energy dissipation processes and the antioxidant enzyme system). This research will permit to obtain a better understanding of the interaction of different environmental stressors on algal and cyanobacterial metabolism. On a long term, this research may help to establish new water quality criteria based on the interaction of pollutants with natural occurring environmental factors.