New Delhi, Oct. 11: India’s unregulated online trade in exotic plants, fish and small animals may pose a threat to local ecosystems through the inadvertent release of invasive species, scientists have warned.
Scientists at the Madurai Kamaraj University have found online vendors in India offering over 900 varieties of exotic fish, some 3,000 ornamental plants and 14 small animals including hedgehogs, iguanas and marmosets.
“We already have several examples of exotic species invading our local ecosytems. Online trade (in such species) could be the proverbial sword of Damocles,” said Sivagnanam Chandrasekaran, associate professor of plant sciences at the university, who led the study.
Chandrasekaran and his colleagues scrutinised the list of fish varieties available for purchase through online transactions and delivered through courier. They have identified some fish that they fear could, if accidentally released, harm local freshwater organisms.
Their survey suggests that online vendors are offering many fish varieties with vivid colours, primarily intended for fish tanks and aquariums. Among these are the arowana and the flowerhorn, which they say are being sold as “vaastu fish” for luck and prosperity.
“We believe that some of these species may have invasive potential and could harm our freshwater bioresources if released,” Chandrasekaran said. “We have no idea how many members of the public and online vendors are aware of this risk.”
The survey’s findings will appear in a forthcoming issue of the journal Current Science, published by the Indian Academy of Sciences.
The scientists identified 21 websites offering online transactions in exotic fish, 12 vendors offering ornamental plants including herbs and shrubs, and 11 selling animal pets, including some species that have demonstrated their invasive potential in other countries.
Hedgehogs, for instance, have been labelled as invasive in New Zealand and Scotland while iguanas have invaded the Cayman Islands, Fiji and Florida, among other sites. Marmosets have been declared invaders in Rio de Janeiro, Brazil.
A field survey of fish farms in Tamil Nadu by the scientists too found exotic fish maintained in open cement tanks in conditions where excess rainwater and overflow could help the fish slip into drainage outlets leading to local water bodies.
Conservation scientists say local online trade in exotic organisms is not surprising.
“There would be at least 200 exotic fish widely available through local offline aquarium shops,” said Rajeev Raghavan, a fisheries biologist at the Kerala University of Fisheries and Ocean Studies, Kochi, who was not associated with the study.
“At least 10 exotic fish species are found in water bodies at various sites in the Western Ghats. We have quarantined sections in all airports but their main task is to screen imports for pests and diseases, not to assess their invasive potential.”
Scientists have in the past cautioned that African and South American catfish, guppies and suckermouth catfish are among exotic species that have moved into local water bodies and are competing with indigenous fish.
People who maintain exotic fish in home aquariums simply dump them in local water bodies when the fish grow too large to be kept at home.
“Some exotic species can tolerate our water conditions better than indigenous fish,” said Benno Pereira, head of the department of fisheries at the St Albert’s College, Ernakulam. “In the competition for resources, the indigenous fish lose out.”
The Madurai Kamaraj University scientists are now analysing the list of plants available through online vendors. “In plants too, there are instances of invasions,” Chandrasekaran said.
Scientists say that the Lantana camara, introduced by the British in Calcutta in the early 19th century as an ornamental plant for its flowers, is among the worst weeds to be documented.
Likewise, parthenium grass, accidentally introduced in Pune during the mid1950s through contaminated wheat shipments from the US, too has spread nationwide over the decades.
