Bioaccumulation of cadmium in gills and muscles of shellifsh from Pulicat lake, Tamil Nadu, India

Objective:To evaluate the presence of heavy metal cadmium in six species of shellfish at Pulicat Lake, Tamil Nadu, India. Methods: Six species of shellfish,Fenneropenaeus indicus,Fenneropenaeus monodon, Fenneropenaeus semisulcatus,Scylla serrata,Clibanarius longitarsus and Meretrix casta (M. casta) in Pulicat lake, Tamil Nadu, India were analysed for the presence of cadmium in the gills and muscles from January 2011 to December 2012. Results:The results showed seasonal variations in the uptake of cadmium. Very high accumulation of cadmium was found in the gills and muscles ofM. casta during post monsoon, summer, premonsoon and monsoon. The corresponding values of cadmium present in the gills of M. casta were 1.59, 1.56, 1.48 and 1.46μg/g in 2011 and 1.16, 1.25, 1.15 and 1.14μg/g in 2012. Whereas for muscles, they were 1.14, 0.11, 0.96 and 0.80μg/g in 2011 and 0.49, 0.34, 1.05 and 1.20μg/g in 2012. Conclusion:The results of the present study has shown that the accumulation of cadmium found in the gills and muscles were high in M. casta when compared to other species of shellfish. Thus, the consumption of the shellfish is safe, but does not exclude bioaccumulation risk in their meat. This present study has highlighted the need for estuarine biomonitoring to avoid possible contamination of shellfish and its consumers. The overall scenario of the shellfish accumulating high levels of cadmium indicates that the Pulicat lake is polluted with undesirable elements and the risk of consuming the meat of shellfish by man and other carnivores may lead to their toxicity. Stringent control measures are necessary to control the pollution of this precious lake to reduce the bioaccumulation of toxic metals in organisms.

Short-term desalination of Pulicat lagoon(Southeast India)due to the 2015 extreme flood event:insights from Land-Ocean Interactions in Coastal Zone(LOICZ)models

Introduction:We investigated the magnitude and duration of desalination of Pulicat—a coastal lagoon ecosystem connected to the Bay of Bengal on the South-eastern coast of India—during the 2015 South India flood event which was a period of high-magnitude precipitation and riverine flooding.Methods:We estimated freshwater runoff into the lagoon using flow accumulation models for a period of 55 days(November 1 to December 25,2015)using daily gridded precipitation data from the Global Precipitation Measurement and a digital elevation model.Using the estimates of freshwater runoff,direct precipitation and observed salinities,we simulated water and salinity fluxes of the lagoon using the Land-Ocean Interactions in the Coastal Zone model.Further,we also used Monte Carlo simulation to estimate the uncertainty in system salinity,the residual salinity at the boundary and the freshwater residence times in the lagoon.Results:We estimated that a high volume(~760×10^(6) m^(3))of relatively low salinity waters(residual salinity=23.47 psu)had been exported from the lagoon to the Bay of Bengal during the period which is likely to have caused a strong dip in the daily salinity profile of the coastal sea.We contend that the lagoon experienced~40%desalination due to the 2015 event with a freshwater residence time of 18.5 days.Conclusions:The study highlighted the short-term,high-magnitude desalination undergone by Pulicat lagoon during the 2015 South India floods.Considering the high residual and exchange volumes obtained from the study,we conclude that Pulicat could be a major exporter of relatively low salinity waters to the Bay of Bengal during monsoons.