Scientists have raised the alarm over the discovery of the black mussel (Mytella strigata), a fast-spreading invasive species, in shrimp farms along Sri Lanka’s northwestern coast near the Anawilundawa Ramsar wetland. Native to the Americas, this mussel has already caused ecological and economic disruptions in the U.S., Southeast Asia, and India’s Kerala backwaters.
Clusters of mussels were first found attached to hard surfaces at the bottom of shrimp ponds that had been free of them just three months earlier. “The speed at which this species spread is alarming,” said Malik Fernando of the Wildlife & Nature Protection Society (WNPS). Researchers warn that its rapid establishment could threaten local biodiversity and aquaculture livelihoods.
Biology Behind the Invasion
According to Sevvandi Jayakody, chair professor of aquaculture at Wayamba University, the black mussel’s success stems from its early maturity, long spawning season, and tolerance for varying salinity and temperature. Its small, elongated shell allows it to disperse quickly and outcompete native bivalves.
In invaded regions, dense colonies clog aquaculture equipment, reduce oyster spat settlement, and interfere with harvesting. A study in Kerala recorded a 38% drop in oyster spat settlement due to black mussel infestations.
Pathways and Prevention
Researchers believe the mussel may have arrived via contaminated shrimp feed, ballast water, or biofouling on ships. Samantha Gunasekara, chairperson of Sri Lanka’s Marine Environment Protection Authority, emphasized the challenges of biofouling, noting that organisms like mussels are harder to remove than ballast water contaminants.
Sri Lanka is part of the IMO’s GloFouling Partnerships project and follows global biofouling management guidelines, but the country has yet to ratify the Ballast Water Management Convention, leaving gaps in prevention measures.
Urgent Need for Action
Experts stress early detection, rapid response, and strict biosecurity to prevent further spread. “Sri Lanka needs a strong pre-exposure strategy and legal framework to manage invasive species,” Jayakody said. Public awareness is also key, as containment will be difficult without cooperation from aquaculture operators and local communities.
With the black mussel already established inside a protected wetland, scientists warn that decisive action in the coming months will be critical to safeguard Sri Lanka’s fragile aquatic ecosystems from this invasive threat.