Monster Seminar JAM - Ecological consequences of patchiness in the coastal ocean
Dr. Kelly J. Benoit-Bird, Department of Oceanic and Atmospheric Sciences, Oregon State University
In the ocean, most resources are heterogeneously distributed and highly dynamic. This patchiness in time and space has significant consequences for population dynamics, trophic interactions, community organization and stability, and the cycling of elements. Recently discovered plankton thin layers (less than 3 m thick) are an extreme case of biological heterogeneity. Our work on thin plankton layers in a variety of habitats including Hawaii, Monterey Bay, and the Oregon coast have now provided the first evidence of trophic interactions in thin layers, shown that biological processes, rather than physical phenomena, can dictate the structure of thin layers, and provided evidence of ecosystem impacts disproportionate to their biomass. By quantifying the relationships between thin plankton layers and their predators, we were able to examine the relative importance of biomass and patchiness in the regulation of a pelagic marine food web. We found that the number and intensity of aggregations at each trophic level rather than the biomass in each step of the food chain involving phytoplankton, copepods, mesopelagic micronekton, and spinner dolphins (Stenella longirostris) were the most significant predictors of variation in adjacent trophic levels. Our results are in accordance with resource limitation - mediated by patchiness - regulating structure at all trophic steps in this ecosystem as well as the behavior of the top predator. The importance of spatial pattern in ecosystems has long been recognized and its effects on predator-prey pairs has been examined in a number of previous studies, however, patchiness as the dominant force regulating an entire system has not been previously demonstrated.
Date and Time:
January 28, 2010,
11:00 am - 12:00 pm