Response of Villorita cyprinoides and Magallana bilineata (Bivalvia) to Environmental Variables in Munroe Island, Kerala, India

The present investigation was aimed at examining the effects of environmental variables on two bivalve species Villorita cyprinoides and Magallana bilineata in the five stations of Munroe Island, Kerala, India during the pre-monsoon period of 2022.The impacts of various anthropogenic activities were noted.Spatial abundance and distribution of these two species were recorded.Moreover, 12 hydrographical parameters were analyzed during the study period.Spatial dynamics of these two species showed that Villorita cyprinoides ranged from 140.25 ind/m 2 (S1) to 185.45 ind/m 2 (S3) and the abundance Magallana bilineata was between 139.12 ind/m 2 (S1) and 175.21 ind/m 2 (S3).Environmental variables like temperature, TDS, EC, salinity, hardness, alkalinity and pH were highest at S3 whereas the BOD and COD were highest at S4.The dissolved oxygen and nutrient parameters were highest at S1.The results of water quality analysis specified the moderate levels of anthropogenic activities in Munroe Island.To ascertain the association between bivalve species and water quality variables, the observed variables were measured through the multivariate statistical tools.The response of bivalves still reflected the moderate pollution status of Munroe Island and also revealed that the bivalves can tolerate adverse environmental conditions.The distribution pattern of bivalves in the present investigation also signified the same.Moreover the influences of both the Ashtamudi estuary and the Kallada River were clearly reflected in the hydrographical and biological variations.