| SS9.01 Ecosystem Science Practiced in an Urbanized Estuary: South San Francisco Bay |
| Fisher, K, E, Los Alamos National Lab, Los Alamos , USA, kefisher@earthlink.net |
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| COUPLING AND DECOUPLING OF PHYSICAL AND BIOLOGICAL DISTRIBUTIONS IN THE SOUTH SAN FRANCISCO BAY SYSTEM IN WET AND DRY YEARS: FRACTAL AND MULTIFRACTAL MEASURES |
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| Multiscale analysis can be used to map differences in spatial structure of biological and physical variables in dynamic environments. Such a mapping strategy allows realistic portrayal of the patch structure observed in the system. USGS data from the monthly monitoring of South San Francisco Bay provides a record of fluorescence, salinity, and temperature that gives insight into spatial structure. Multiscale analysis suggests that wet and dry conditions lead the relation of fluorescence to the two physical variables into distinctly coupled and uncoupled states. In wet years, wavelet-based power spectra have similar slopes for all three variables over the range of 60 meters to 1.5 km. In dry years, the spectral slopes of fluorescence are flatter than for the other two variables. These differences in spatial structure are consistent with expected effects of benthic grazing pressure. Given the complex interplay of oceanic and land-based supplies of water to the basin, the evolution of these two distinct patterns has implications for modelling the system, and for using the relationship between spectral slope (beta) and fractal dimension in generating input fields to be used in ecosystem models of South San Francisco Bay. Multifractal analysis adds the descriptive power of higher order moments characterizing the intermittency of the system, and provides a valuable tool for further distinguishing between cases in which identical power-spectra result from different patterns. |
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