Research interests ecology of aquatic microorganisms and the ecological role of sediment bacteria, particularly in estuarine and marine sediments, and in peat soils cycling of C, N and S in estuaries, in mangrove swamps and in Antarctic environments production of trace gases (CH4, N2O, DMS) by bacteria in aquatic environments, and their exchange with the atmosphere processes controlling production and oxidation of CH4 by bacteria in peat bogs and in landfill sites physiological response of bacteria to temperature,particularly low temperature ecophysiology of denitrifying bacteria influence of transient environmental conditions on competition and survival multidisciplinary approaches to ecological research