Ecology of marine benthic algae; interactions between plants and animals; biophysical climatic models; ecology of new aquatic species.
Research programs :
Marine ecology: Intertidal and shallow subtidal communities are important components of coastal ecosystems and also serve as models for the studies of the structure and function of ecological communities in general. In particular, they permit the experimental investigation of the interplay between physical and biological factors in controling intra-specific and inter-specific interactions. Research in my laboratory focuses primarily on the ecology of algae and the herbivores that eat them. Current projects include (1) the development of microclimate models for predicting the stresses experienced by intertidal plants and animals during low tide and how variation in these stress may affect the establishment of individual macroalgae and the development of algal turfs, and (2) the establishment and persistence of small kelp beds in shallow subtidal communities dominated by urchins. In both these system, we are examining the effects of variation in the physical environment (e.g., desiccation, wave exposure) on the extent and intensity of herbivory. We are particularly concerned with the effects of small-scale surface topography on the recruitment of algae, especially the small post-settlement stages.
Biological invasions: The natural communities of our world are being degraded by the introduction of non-indigenous species. Modern methods of transportation and increasing global trade have greatly accelerated this process in aquatic communities. My laboratory's research in this area concerns the post-introduction dispersal and spread of exotic species as well as their impact on native species and the ecosystems in which they are found. Again, our emphasis is on the factors that control species establishment including propagule production, dispersal, and recruitment. Past work has been primarily on the zebra mussel invasion of inland lakes but I hope to expand this area of research into other exotic species and environments.
Publications :
Winkler G, Sirois P, Johnson LE & Dodson JJ (sous presse). "Invasion of an estuarine transition zone by Dreissena polymorpha veligers has no detectable effect on zooplankton community structure", Canadian Journal Fisheries Aquatic Sciences,
Johnson LE, Bossenbroek JM & Kraft CE (sous presse). "Patterns and pathways of the post-establishment spread of non-indigenous aquatic species across multiple spatial and temporal extents: the decelerating invasion of inland lakes by the zebra mussel", Biological,
Gagnon P, Johnson LE & Himmelman JH (sous presse). "Spatial and temporal stability in algal assemblages on urchin barrens in the northern Gulf of St. Lawrence", Journal of Phycology,
Pardo L-M & Johnson LE (sous presse). "Variation in life-history traits across an intertidal gradient: environmental effects on size, growth and fecundity in a marine snail", Marine Ecology,
Pardo, L-M & Johnson LE (2004). "Activity and shelter use of an intertidal snail: effects of sex, reproductive condition, and tidal cycle", Journal of Experimental Marine Biology and Ecology 301: 175-191,
Department of biology, Pavillon Alexandre-Vachon, 1045, av. de la Médecine, Université Laval, Office 3058, Québec(Québec) G1V 0A6 Canada Tel : 418 656-3180 Fax : 418 656-2043 Email :info@bio.ulaval.ca
