BioScience 

Abstract: Eutrophic systems, on the other hand, rarely achieve the status of a stable, climax community. The continuous supply of nutrients to these environments sustain high levels of photosynthetic production. If processes of advection or decomposition of the resulting living and dead organic matter cannot keep pace with its rate of production, this material may accumulate to the point where it exceeds the carrying capacity of the water. These extreme conditions lead to the development of anoxic and eventually abiotic environments. Even when a balance between the production and loss of organic matter produces a quasi-steady state, small perturbations in physical and chemical parameters (radiation, nutrient input, temperature, etc.) cause photosynthesis and respiration to vary widely in absolute terms and with respect to each other. Long-term balance and stability are not readily achieved under such conditions. Eutrophic communities tend to be either highly productive or respiratory, and when the oscillations become great enough, periodic mortalities occur. The alternation between productive and destructive processes that takes place in these eutrophic environments has a pronounced effect upon the kinds of biological communities that inhabit them. As mentioned above, succession leading to a stable and diverse climax community is not possible. The larger, slow-growing carnivores high on the food chain do not prevail, at least as resident populations. Small herbivores that can reach maturity in weeks to a few months, whose populations can respond quickly to favorable conditions and recover rapidly from mortalities, predominate. This is true particularly of the fixed benthos, but is also typical of the pelagic fish populations, which are characterized by small, rapidly growing species such as herrings, sardines and anchovies that can avoid the deeper, anoxic layers, are short-lived and subsist on plankton near the base of the food chain. Furthermore, as eutrophication increases, an increasingly larger fraction of the organic production becomes channelled into species that are too small or otherwise unsuitable or useless as food for man. In the absence of a