Kim Engineering Building, Lecture Hall, Rm. 1110
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Booz Allen Hamilton Distinguished Colloquium in Electrical and Computer Engineering
"Using Sound to Reveal Patchiness in the Coastal Ocean and Its Ecological Consequences"
Prof. Kelly Benoit-Bird
College 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. However, this heterogeneity also presents a significant sampling challenge. Recently discovered plankton thin layers (less than 3 m thick) are an extreme case of biological heterogeneity that are often missed by traditional sampling approaches. We used a combination of new acoustical and optical techniques to show that thin plankton layers in a variety of habitats including Hawaii, Monterey Bay, and the Oregon coast can have ecosystem impacts disproportionate to their biomass. By using these new tools to quantify 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. Data from a cutting edge, three-dimensional multibeam sonar revealed that spinner dolphins specifically exploit patchiness, further aggregating existing prey resources through cooperative behavior. A passive acoustic array showed that unique acoustic signaling was used by these animals to coordinate this highly stereotyped, social foraging. 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, primarily because of the technical challenges of measuring the spatial and temporal scales of biological variability in the ocean.
Dr. Kelly Benoit-Bird, an Associate Professor in the College of Oceanic and Atmospheric Sciences at Oregon State University, is the author of more than 30 journal publications applying acoustics to study the ecology of pelagic ocean ecosystems. Her work examines a wide range of animals including zooplankton, fish, squid, and marine mammals, in all cases emphasizing the mechanisms creating spatial and temporal dynamics in pelagic marine ecosystems, the effects these dynamics have on interactions between organisms, and the mechanisms animals use to cope with these patterns. She has been involved in the development of several new optical and acoustical instruments and has made fundamental acoustical measurements of a variety of species in the process of addressing ecological processes in the ocean. Dr. Benoit-Bird’s work was recently recognized by the Acoustical Society of America with the 2009 R. Bruce Lindsay Award for “contributions to marine ecological acoustics” and the American Geophysical Union which awarded her the 2008 Ocean Sciences Early Career Award for “innovative application of acoustical techniques”. Kelly is also the recipient of a United States Presidential Early Career Award for Scientists and Engineers, a Young Investigator Award from the U.S. Office of Naval Research, and a U.S. National Academy of Sciences Kavli Frontiers Fellowship.
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