The discovery of the invasive black mussel (Mytella strigata) in shrimp farms along Sri Lanka’s northwestern coast has alarmed scientists, who warn that the species could spread rapidly and disrupt the country’s aquatic ecosystems, said a report published yesterday by the Mongabay.

Clusters of the mussel were first detected in September 2023 during surveys for a mangrove restoration project near the Anawilundawa Sanctuary, a Ramsar-listed wetland. Researcher Thilina Kumarasiri initially found empty shells in supply canals, which were later confirmed by conservationist Malik Fernando of the Wildlife & Nature Protection Society as belonging to M. strigata.

Originally from the Americas, the species has become a notorious invader in Asia, including India’s Kerala backwaters, and is known to foul aquaculture systems, clog fishing nets and reduce oyster settlement. Its rapid growth was evident in Anawilundawa, where drained ponds revealed thick mats of mussels attached to pond bottoms and hard surfaces within months.

“The speed at which this species spread in the pond was alarming,” Fernando said. “It suggests the mussel could establish itself quickly in similar habitats.”

According to Wayamba University’s aquaculture expert Prof. Sevvandi Jayakody, the mussel’s resilience lies in its biology: early maturity, long spawning seasons and tolerance to wide salinity and temperature ranges. She warned that its spread through Anawilundawa’s waterways could threaten sensitive wetland ecosystems if unchecked.

Scientists suspect the mussel may have arrived via contaminated live shrimp feed, ballast water from ships or biofouling on hulls. Sri Lanka, though part of the IMO’s biofouling management initiative, has yet to ratify the Ballast Water Management Convention.

Experts are calling for urgent monitoring, containment and stronger invasive species laws. “Rapid eradication is essential,” Jayakody said. “Without swift action and public awareness, this invader could become another costly ecological burden.”

Samantha Gunasekara, Chairperson of the Marine Environment Protection Authority in Sri Lanka, explained that ballast water — seawater taken on by ships for stability — is often loaded in one port and discharged in another, unintentionally transporting marine life across oceans.

Biofouling, the buildup of organisms such as barnacles, mussels and algae on submerged surfaces like hulls and propellers, is another vector. “Unlike ballast water, which can be treated, biofouling organisms can be physically stubborn and harder to remove,” Gunasekara noted.

Sri Lanka is one of 12 countries in the International Maritime Organisation (IMO)-led GloFouling Partnerships project, which promotes good biofouling management practices. “Even though the project ended in May 2025, we continue to support partner countries with pilot projects and sustainable technologies,” IMO technical analyst Will Griffiths said.

Many biofouling species can survive extended journeys, even across different water temperatures and salinities, so the project spurred the development of good practices and standards for improved biofouling management, Griffiths said.