Seasonal variability in the water quality, sediment characteristics and macrobenthic community structure in the vicinity of finfish cage culture sites in a tropical estuary along the south-west coast of India

Cage culture in estuaries and backwater systems is augmented as an source of income among the coastal population. However, growing popularity of cage culture has resulted in its expansion a greater level. Hence the present study was carried out to identify impacts associated with cage culture on the water quality, characteristics, macrobenthic abundance, and the structure of the fishing island Pizhala on the southwest of India on a seasonal scale. The sample was taken from six near the cage (<1m) and two reference stations (200-300 away). The study revealed significant variation in the water quality the seasons. The DO concentration during pre-monsoon (PRM) had considerable variation between the cage sites and sites (RF). The sediment organic carbon in cage sites was higher than the RF irrespective of the season. The RF had higher species diversity than the cage sites contributed by sensitive organisms like amphipods. The feeding guild revealed a higher abundance of sub-surface deposit feeders (SSDF) and surface deposit feeders in the cage sites corresponding to increase in the sediment organic carbon concentration.