A tiny snail with a striking, pellucid golden-yellow shell found in the Edappally canal in Kochi has been flagged as an invasive species that could play havoc with native ecosystems.
Having come across it during a biodiversity impact assessment study, researchers of the Department of Marine Biology, Microbiology, and Biochemistry of the Cochin University of Science and Technology (CuUSAT) have pinned it down as the acute bladder snail Physella acuta , globally branded as highly invasive.
This is the first time that this snail has been reported in Kerala, according to the research team. What makes its discovery worrying is that it plays host to worms that can cause food-borne diseases and skin itches in humans. Moreover, its rapid growth rate, air-breathing capability, and tolerance to pollution makes the Physella acuta a potential competitor to native fauna.
The findings by S. Bijoy Nandan, Dean, Faculty of Marine Sciences; postdoctoral fellows P.R. Jayachandran, R. Radhika, B.P. Aneesh, K.S. Santu, and research scholar M. Jima have been detailed in the scientific journal Proceedings of the Zoological Society .
Using a scoop net, the team recovered 23 live specimens from the Eroor part of the Edappally canal during the biodiversity impact assessment carried out for the Integrated Urban Regeneration and Water Transport System (IURWTS) in Kochi.
The specimens were found clinging to Ceratophyllum demersum , an invasive freshwater plant, and other gastropod species such as Indoplanorbis exustus and Racesina luteola . “Ceratophyllum demersum is used as a decorative plant in aquariums,” said Dr. Jayachandran.
First described by J.P.R. Draparnaud in 1805, Physella acuta is considered native to North America but is now found in all continents except Antarctica. The snail was first reported in India in the early 1990s. It is believed to have reached Kerala through the aquarium trade, a major vector for invasive species. In the Edappally canal, the snail had made its home in a highly polluted reach plagued by high sedimentation, untreated sewage, commercial effluents, construction wastes and a thick growth of invasive aquatic weeds.
Small in size, the snail can grow to 16 mm in height and 9 mm in width. The dead, vacant shell is brownish-yellow while that of the live individuals are translucent golden-yellow with a mottled appearance. Physella acuta is easily identified by its sinistral (left-opening aperture) shell. Its good looks make this snail a favourite of aquariums, but Dr. Jayachandran is quick to add a warning note. “Special care should be taken while dealing with this snail and it should not be kept in home aquariums,” he said.
The CUSAT study also draws attention to the threat posed by invasive species to global biodiversity; how their ability to quickly dominate new environments endanger native species, even causing serious economic loss.
