Noxious bloom events are becoming more prevalent with increasing anthropogenic activities. To lessen ecological damage, there is a need to develop phytoplankton management programs aimed at enhancing growth of beneficial algae. The success of such management schemes will be dependent on the predictability of phytoplankton succession within the target system to a controlled perturbation. Freshwater lakes appear to exhibit a degree of predictability as described by the conceptual model of the Phytoplankton Ecology Group (PEG-model) and Equilibrium Resource Competition theory (ERC-theory). Using mathematical models and field data collected from the Nueces River estuary, Texas, I investigated whether the PEG-model and ERC-theory could be applied to a marine system. I also investigated approaches to managing phytoplankton community composition through nutrient loading.

Initial growth and accumulation of biomass of edible phytoplankton forms after a favorable nutrient perturbation, a predominant feature of the PEG-model, was consistently observed in the field data and mathematical models. Dominance of phytoplankton species with optimal nitrogen to phosphorus ratios similar to ambient nitrogen to phosphorus ratios, the crux of ERC-theory, was not consistently observed in the field data or mathematical models. Rather the ability of a phytoplankton species to successfully compete against other algae was a function of its physiological growth and morphological characteristics.

In the Nueces River estuary, succession within the phytoplankton community showed a degree of predictability to nutrient perturbations. Therefore, management of the phytoplankton community composition may be possible. The PEG-model appears to be a useful guide for a phytoplankton management scheme, while the utility of ERC-theory may be limited. The mathematical models indicated that supplying the nutrients to an estuary in a pulsing fashion may allow greater growth of beneficial algae and subsequent growth of copepods. Further model refinement and characterization of the target system (in this case the Nueces River estuary) are necessary, however, before models of this nature can be used as a guide to phytoplankton management programs.