Diel variations in zooplankton populations in mangrove ecosystem at Gaderu canal, southeast coast of India

Abstract

To determine this energy flow 24 hours cycles were carried out in the Gaderu River which flows through dense mangrove vegetation. The day time planktonic composition was rich with phytoplanktonic community and detritus, which is the main source of food for the organisms living in the mangrove ecosystem. The temperature and salinity reflected the conditions of the bay while the plankton had direct relationship with the nature of tide, strength of the current and direction of flow. Higher displacement volumes of about 0.73, 0.75, 0.85 ml.m-3 were recorded during night with numerical abundance of 27053, 17401 and 18688 no.m-3 respectively. The detritus constituted about 50-60U+0025 during the low tide period. Among the zooplankton, copepods and larvae of molluscs and polychaetes contributed to the bulk of zooplankton component. In spite of the fluctuating currents, regular diurnal rhythm was observed for many of the holoplanktonic and meroplanktonic forms.