Zooplankton of the lagoons of the Laccadives: diel patterns and emergence

Zooplankton populations in the water column increased substantiallyat night in four lagoons of the Laccadives. Epibenthic formsemerging into the water column during night, as well as non-epibenthicforms such as calanoid and cyclopoid copepods, were responsiblefor this. Unsealed traps were found subject to contaminationand hence less reliable in estimating densities of emergingfauna compared with sealed traps. Direct sampling of the substratumduring daytime showed that the actual densities of epibenthicforms are much higher than those observed in traps. Densitiesof emerging plankton varied geographically. Most of the zooplanktonorganisms which contribute to the lagoon fauna are residentin the lagoons and rarely occurred in the surrounding sea