Basic and Applied Zooplankton Biology

Abstract

Zooplankton (In Greek: Zoon – animal; Planktos – wanderer/drifter) are minute, mostly microscopic drifting creatures mainly inhabiting the surface layers of aquatic ecosystems like seas, oceans, lakes, rivers, and ponds. The zooplankton along with phytoplankton forms the basic tiers of aquatic food chains and thus feeding the higher tropic organisms like fishes. The zooplankton comprises of wide range of organisms that are classified based on their size, depth, and geography of distribution and mainly in relation to their life cycle. While the holoplanktonic zooplankton lead their entire life as planktonic-mode of life (e.g., radiolarians), the meroplanktonic forms spend only their early stage of life as “plankton” and later stage as “nekton-swimmers” (e.g., eggs and larvae of fish). Their primary sources of food include bacterioplankton, phytoplankton, marine snow (detritus), and also some smaller zooplankton. Therefore, they are the primary consumers or secondary producers and hence form a vital link in the aquatic food web. Their distribution, abundance, and seasonal changes have a major impact on the annual fishery productivity/ yield across the world’s oceans. During the death and decay of these creatures, the carbon containing organic material sinks down onto deep oceans and thus they play an important role in carbon cycle.