Population and community patterns of marine fish diversity: effects of exploitation and climate

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Marine biodiversity, particularly patterns of fish diversity and the processes that maintain or change diversity at both the population and community level continue to be focal points of my current research. This has led to an examination of the consequences of changing diversity on ecosystem structure and function. The primary drivers of changing diversity in the continental shelf ecosystems under investigation are i) fishing effects, whose scale and magnitude (both direct and indirect) has increased dramatically in recent decades and ii) climate variability. Our recent research has revealed that depletion of large predators can cause a restructuring of some large, open-ocean systems through cascading trophic interactions, extending to the base of chain and altering primary production and nutrient cycling. Planned research on fish species diversity at the community level is based on one of the cornerstones of modern ecological science and conservation biology - the species area relationship or SAR. I intend to use this relationship for understanding how marine fish communities are organized and for determining if conservation protocols that follow from it are practicable and can be justified. The former thrust will involve a determination of the ecological basis for the existence of SAR. This will involve an assessment of the relative influence of habitat diversity, resource concentration and area per se, as described in the equilibrium theory of island biogeography, as the processes shaping the empirical relationship. The latter, more applied thrust involves prediction of species losses from habitat losses, systematic evaluation of the slope of SAR from areas subjected to varying exploitation regimes, and determining whether or not bigger really is better for maintenance of biodiversity, in terms of reserve design. I continue to make use of monitoring data obtained from standardized research surveys conducted by government agencies across the Northwest Atlantic. The surveys, based on consistent sampling methodology, have yielded detailed time series of variation in abundance, spatial distribution and species diversity across multiple trophic levels at broad spatial (100-1000+ kms) and temporal scales (most established and maintained since early 1970s).