Why is relating plankton community structure to pelagic production so problematic? It is an interesting question to attempt to answer. Certainly, the various components of plankton communities can be quantified. Further, many species properties, for example morphology, life history stage and certain aspects of physiology, can be determined in considerable detail, and there is promise of improved precision using tools such as molecular genetics. Nevertheless, although these general features have

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... been identified, appreciation of the nature of the properties that gear a given species to a specific aquatic environment, and which are responsible for its occurrence, persistence or dominance in a given water mass, is poor at best. Knowledge of temporal and spatial distribution patterns of many species is now fairly sound, yet it is not known why they occur when and where they do. Therefore, efforts at prediction often fail. Consider the terrestrial example: it is known how water supply regulates the extent and type of vegetation, e.g. forest v. grassland v. desert. Specific morphotypes, such as tree roots, trunk and crown, are recognized as adaptations to a combination of environment and competition. Within the primary morphotype "tree" can be distinguished those resistant to fire and those less susceptible to generalist herbivores (from insects to mammals) on the basis of bark, leaf type, presence or absence of secondary chemicals (ethereal