Bioinvasion of Mytella strigata (Hanley, 1843) in Ashtamudi Lake, Kerala, India – is pollution aggravating environmental degradation in Ramsar wetland?

Abstract

Polluted or degraded aquatic ecosystems accumulate more invasive species than less polluted areas. The alien invasive mussel Mytella strigata (=charruana) was reported to be affecting wild spats of mussels as a dominant competitor for space on floating substrates which is native to Central and South America later outspread to east coast of central Florida and subsequently reported from Philippines. The tremendous increase of M. strigata population in Ashtamudi Lake is raising an alarming situation over the native bivalve species as it compete for space, breeding ground, substrates and food. The broad salinity ranges allows them to invade via ballast exchange of water and the fouled ship hulls. When salinity levels goes beyond the thresholds of the native species, M. strigata can sometimes outcompete them. Moreover, the molecular phylogenetic analysis via COI sequences shows a close genetic relationship shared between the native mussel Perna viridis and the alien invasive mussel M. strigata. The increasing pollution load along with the solid waste disposal in the Lake, is accelerating the spat fall of M. strigata over the native species and therefore should be a priority in the bioinvasion control, otherwise can lead to displacement or local extinction of the native species.