6533b821fe1ef96bd127b6c4

RESEARCH PRODUCT

Differential attributes of phytoplankton across the trophic gradient: a conceptual landscape with gaps

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I provide a conceptual landscape of attributes of phytoplankton related to trophic gradients, by reviewing 69 papers and books on eutrophication, with special reference to the ecology of the phytoplankton. Forty-eight ecological variables such as total phosphorus and Chl-a, are used, each related to the trophic gradient measured. They are subdivided in structural features of the phytoplankton, functional or dynamic features, and other relevant properties of the plankton community. Only twelve of the forty-eight variables are statistically related to trophic gradient. In most cases, variability across a trophic gradient is only nominally described. Less attention is given to functional, structural or dynamic variables. Some associations occur because the variables are interrelated, for example, photosynthesis and Chl-a, or because the mathematical comparison is between a whole factor and a part of it. Many important environmental features which trigger or affect phytoplankton behaviour are independent of trophic state. Therefore, trophic states might be viewed as a multi-dimensional space, the axes of which are defined by the various independent variables, and not merely a simple gradient of fertility. The alternative approaches to the search for pattern are either the single global pattern (which seeks to explain the ecological behaviour of phytoplankton in all freshwater systems) or multiple local patterns (where only a small set of specific variables is solved for each question and system). If the ultimate goal is a paradigm of phytoplankton dynamics, biomass models, and tools for the prediction of species composition, phytoplankton ecologists should adopt the theories of nonlinear dynamic complex systems.