Kochi

Presence of invasive mussel confirmed in Kochi backwaters

The black-striped mussel is an invasive species in many parts of the world.

The black-striped mussel is an invasive species in many parts of the world.  

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The fast-growing species can tolerate a wide variety of environmental conditions

From clambering lantana plants to karimeen-like red-bellied paku, invasive species come in all sizes. The latest addition to Kerala’s invasives list is only around a centimetre or two long: scientists have confirmed the presence of the invasive black-striped mussel Mytilopsis sallei in Kochi’s backwaters.

'Alien' mussel

In a study published on December 25 in the scientific journal Current Science, researchers at the Cochin University of Science and Technology (Cusat) used basic genetic methods to confirm the identity of mussels they collected from Cochin harbour and Ezhupunna in Alappuzha. They extracted DNA from these mussels. While running this through an international online database, they matched it to the DNA of mussels observed from the Lam Tsuen River in Hong Kong (China), confirming that it is the same species that is now found in Kochi’s backwaters.

The black-striped mussell, native to the South and Central Americas, is an invasive species in most parts of the world and has been recorded from countries including Hong Kong, Australia and Japan. In India, it has been recorded from the ports of Mumbai (Maharashtra) and Vishakapatnam (Andhra Pradesh). It spreads primarily through the discharge of ballast waters of ships (seawater carried in the ballast tanks of ships to improve its stability and balance). The fast-growing species – which dwells in shallow water – can tolerate a wide variety of environmental conditions (salinity, water temperatures and oxygen levels; tests in the laboratory confirmed this again), which helps them thrive in the new areas they colonise.

The researchers estimate that one square metre near Fort Kochi (from where they collected some of the mussel samples) contains as many as 748 individuals. This is extremely high, said Dr. Bijoy Nandan, professor at Cusat’s Department of Marine Biology and one of the scientists who conducted the study.

Several costs

Though tiny, these invasive mussels are ‘biofoulers’, he added: organisms that accumulate on wet surfaces, causing huge ecological and economic losses. They can cause the deterioration of coastal infrastructure; the Australian government, for instance, spent approximately US$ 2.2 million to eradicate Mytilopsis mussels from Darwin Harbour. The mussels can also displace native species of clams (which local fishermen depend on for their livelihood) from their coastal habitats and cause a reduction in native biodiversity. Now the mussels can be spotted along most of Kerala’s coastline, added Dr. Nandan.

“We do not know what other problems could occur if these black-striped mussels proliferate,” said Dr. Nandan. “Or if changing climates could be enhancing their survival in any way. Our molluscan resources are extremely under-studied and we need more research to address these gaps.”

If their numbers grow, harvesting the mussels for use as poultry feed or manure could be a possible management tool, he said.

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Printable version | Jan 26, 2020 11:54:36 PM | https://www.thehindu.com/news/cities/Kochi/presence-of-invasive-mussel-confirmed-in-kochi-backwaters/article25881972.ece

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