Microplastics in decapod crustaceans: Accumulation, toxicity and impacts, a review.

The presence of microplastics in the aquatic environment poses a serious threat not only to aquatic organisms but also to human beings that consume them. The uptake and effects of microplastics have been studied in almost all groups of aquatic organisms. This review details the different aspects of microplastics exposure in an ecologically and economically important group of crustaceans, the Decapods. A majority of Decapod crustaceans such as prawns, shrimp, crabs, lobsters and crayfish are consumed as seafood and play important roles in food chains and food webs. Numerous studies are available on the accumulation of microplastics in tissues such as the gills, hepatopancreas and gastrointestinal tract in these organisms. Experimental studies have also highlighted the toxic effects of microplastics such as oxidative stress, immunotoxicity and reproductive and developmental toxicity in them. This review also summarizes the ecological impacts and implications in human beings as well as lacunae with regard to microplastic uptake in Decapods.

The Backwater Clam (Meretrix casta) as a bioindicator species for monitoring the pollution of an estuarine environment by genotoxic agents.

The coast of Goa receives anthropogenic stress through its major rivers, which carry mining wastes, including iron and manganese ores from upstream mining sites, and petroleum hydrocarbons from shipping activities. These contaminants show seasonal variation in concentration and may be bioaccumulated by fauna inhabiting these waters. These fauna, including the bivalve molluscs, are particularly at risk due to these insults. In the present study, the use of the backwater clam, Meretrix casta (Chemnitz), as a bioindicator species was evaluated, comparing two sites (Vasco and Palolem) on the Goan coast. DNA damage was assessed in the gill cells using the micronucleus and comet assays; physiological condition was determined from the condition index. These values were tested for correlations with the concentrations of total petroleum hydrocarbons and trace metals in the whole soft tissues and with the physico-chemical parameters of water from these sites. Specimens collected from Vasco showed high incidence of micronuclei and % tail DNA and a low condition index ratio compared to those from Palolem, which correlates with the higher level of pollutants in the bivalves the former site. We believe that M. casta is a suitable species for biomonitoring studies of this type.