I am interested in the behavioural and physiological ecology of marine invertebrates with applications to simulation modelling, global climate change and the ecology of invasive species. In particular, I determine the role of zooplankton in marine ecosystems, including planktonic tunicates and suprabenthic zooplankton. Recently, I have been focusing on seasonal dynamics of lipids and fatty acids to determine the response of zooplankton to phytoplankton blooms and to elucidate seasonal cycles of reproduction and energy storage. My work on invasive species is focused on two non-native ascidian tunicates that we have found in some harbours on the south coast of insular Newfoundland, Botryllus schlosseri and Botrylloides violaceus. We have determined the seasonal cycles of somatic growth and reproduction of B. schlosseri and found that it has made life history adaptations to the short growing season and long winters in Newfoundland. We are also developing TaqMan QPCR assays for species-specific identification of larvae and colony fragments in water samples based upon partial sequences of the cytochrome c oxidase I gene of mitochondrial DNA. My research on planktonic tunicates is presently focused on the population ecology and genetics of the pan-Arctic appendicularians Oikopleura vanhoeffeni, O. labradoriensis and Fritillaria borealis. We have found that these 3 species have very specific temperature-and-salinity niches in Newfoundland fjords and have developed a technique of using statolith diameter as a proxy for age in field populations. It seems that O. vanhoeffeni has evolved to have a long life span and reproduce at a large body size, whereas O. labradoriensis has evolved to have a shorter life span and reproduce at a smaller body size. These disparate life history adaptations have major implications for the separation of these congeneric species in space and time.