ON THE DIETS OF CALANOID COPEPODS

A review of the literature (ca 1900 to 1992) on copepod feeding indicates that combinations of stochastic and deterministic processes result in behaviors, or feeding strategies, that optimize nutritional gain from the food environment, and further, that strategies change in response to environmental variability. Because the diet is the product of a feeding strategy, one may gain insight into the ways in which copepods respond to their food environments by measuring their diets. Investigations of the links between copepod feeding and production suggest that dietary diversity is often a key to the procurement of a nutritionally complete ration, and the optimization of secondary production within constraints dictated by the physical environment. The ability to eat different kinds of foods (omnivory) and the tendency to include a variety of foods in the daily ration may enhance the probability of obtaining a nutritionally complete ration in variable, nutritionally dilute, food environments. The notion that the relationship between feeding and production in copepods is driven by dietary diversity is derived in part from a recent recognition of the diversity of microplanktonic organisms that potentially or actually contribute to the diet. Further, the concept is consistent with current trophic dynamic models in which food webs are envisioned as complex interwoven systems rather than short, simple chains.