Zooplakton Methodology Manual

Abstract

This chapter helps in increasing the comparatively sparse knowledge of all aspects of zooplankton ecology by a joint effort on the basis of intercomparable methods for understanding and predicting the impact of environmental changes on fish stocks. The chapter focuses on the role of zooplankton in modeling the cycling of biogeochemical key elements such as carbon, nitrogen, and phosphorus in the sea. Usually, the entire zooplankton community is considered when measuring zooplankton biomass and estimating its production. By employing different mesh sizes in nets and sieves, it is possible to separate the main components from each other, for instance, microzooplankton from esozooplankton or small herbivores from larger carnivores by means of size fractionation. This approach may occasionally prove quite successful, depending on the size spectra and diversity of the species. Bulk parameters obtained in this way may provide useful data for modelers. However, it is always necessary to realize that such data are no more than a methodological compromise, for reality is far more complex. The trophic role and ecological significance of zooplankton communities depend on the diversity, behavior, and interaction of their species. These communities are often dominated by the key taxa, which play the main role in channeling energy up the food web and exercising top-down control through grazing or predation. Future research should put more emphasis on special environmental adaptations of these predominant species and on their ecological significance in forming the food web.