A spatial modeling approach to pelagic ecosystems.




Show, I.T., Jr.

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Texas A&M University.


A modeling technique is developed and applied to two different marine ecosystems problems. The technique approaches marine systems through the mathematical modeling of spatial patterns and deals with spatial heterogeneity in marine zooplankton and environmental parameters. In one instance, the spatial distribution of the copepod, Acartia tonsa, in East Lagoon, Galveston Island, Texas is modeled. The East Lagoon model is driven by a dynamic three-dimensional physical numeric model which provides current velocity, temperature, and salinity feilds. The biological model uses these fields to determine the spatial patterns of A. tonsa in terms of its response to current velocity fields, behavioral responses to temperature and salinity gradients, intranspecific aggregation, and birth-death processes. The model yields stochastic means and variances. The results are shown to closely approximate field data from East Lagoon. In the other instance, the model deals with the combined effects of vertical migration and horizontal advection on the spatial patterns of four species of Pteropods in a cyclonic Gulf Stream ring. This form of the model contains only components dealing with horizontal current velocity fields and vertical migrations. However, one simulation involves a predator-prey submodel. The Gulf Stream ring study is a numerical experiment not backed by sampling data. It clearly demonstrates the dangers of not including spatial considerations in certain classes of marine ecosystems models.


135 p., Dissertation


mathematical models, modeling, geographical distribution, copepods, Acartia tonsa, ecosystems, pelagic environment