Phytoplankton are the base of the food chain and animal productivity depends on the available phytoplankton biomass. Bacteria are the major decomposers of organic matter and consumers of dissolved oxygen. In areas where the inputs of organic matter are high, due to urban activities for example, bacterial respiration can reduce the dissolved oxygen to levels that are deleterious to other organisms. Bacteria also constitute a large biomass which is a source of food for specialized predators and many bacterial species are pathogens of higher organisms. My research is focussed on assesing the role of bacteria in trophic dynamics and in the biogeochemical cycling of carbon.
Diatoms account for most of the marine primary production.
Dinoflagellates are characterized by the pigment peridinin which gives them a distinctive reddish-brown color. Some species contain toxins which can accumulate in shellfish, and can also cause massive fish kills. Dinoflagellates account for most of the bioluminescence observed in surface waters. Generally, diatoms species dominate the phytoplankton assemblage during fall and winter. Dinoflagellates become abundant during the spring and summer.