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Scuba Science 5 - How Spatial Detail Changed Considerations of Marine Ecosystems

Robert S. Steneck and Suzanne N. Arnold University of Maine BIO - http://decostop.si.edu/sds/sds/speaker_bio.cfm?SPEAKER_ID=1 Critical spatial and temporal patterns are revealed using scuba as a research tool that shed light on the rates and processes structuring marine populations, communities and ecosystems. We illustrate this with our research in Maine, the Caribbean, and Alaska. Maine lobsters are New England's most valuable marine resource. Fisheries biologists had treated them as particles randomly distributed in space and time within the Gulf of Maine. We learned that lobster populations depend on carefully selected habitats at the time of settlement. Their nursery habitat is a demographic bottleneck for the species. Scuba monitoring of settlement habitats is now central to their management. In Caribbean coral reefs, our research showed that highest rates of productivity and herbivory occur in shallow water habitats having the lowest algal biomass. After Diadema succumbed to disease in the mid 1980s, herbivory plunged while the productivity potential of the benthos remained unchanged. Rapidly and predictably, biomass peaked at depths of 3-10 m. The structuring dynamics had shifted to a new baseline. Changes in herbivory relative to productivity drive the recruitment potential of coral reefs and fundamentally change the rates at which coral reef ecosystems can recover from human and natural disturbances. In Alaska's Aleutian Islands, we found thick, undisturbed specimens of a crustose coralline alga that lives over 1000 years. Its growth rate reflects kelp abundance, which is controlled by urchins, which are themselves controlled by sea otters. Isotopes allow reconstructions of paleoceanography, so we reconstruct centuries of climate and trophic dynamics. So far we see recent changes correspond, as expected, with local sea otter abundance, and surprisingly, also see sea otters recovered from overharvesting in the mid 1800s but reversed when Russia sold Alaska to the US (1867). Without spatially explicit scuba generated data, this information would not be available for application for fisheries management. Recorded 05/24/10 9:59AM
Length: 17:29

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