Extreme climate events may see alien species in India

A recent paper by Indian scientists from the University of Kerala in the journal ‘Biological Invasions’ has warned that extreme climate events may aid the spread of alien species in biodiversity hotspots in the country.

The paper states events such as the 2018 and 2019 flood-driven release of alien species like the alligator gar from illegal aquaculture farms in Kerala to its natural water bodies.

As reported by Mongabay-India, the researchers say that compliance and enforcement of existing environment protection laws in India can check the spread of alien species. An exclusive policy on invasive alien species and overseeing agency may give more teeth to management of such species. Countrywide assessment of impacts of these species on the economy, biodiversity and food security are needed to understand the nuances of the issue.

Degrading quality of natural water bodies and rivers, coupled with climate change impacts, could set the stage for alien (invasive) species to take root, multiply and alter aquatic flora and fauna in biodiversity hotspots, warned scientists, documenting alien fishes in the Western Ghats.

The paper’s abstract states that focusing on extreme climatic events in India’s Western Ghats Biodiversity Hotspot, the scientists demonstrate that unmanaged aquaculture and unregulated fisheries can often combine with extreme climate events in exacerbating biological invasions through the unexpected introduction and escape of novel alien species. High magnitude flooding events in August 2018 and 2019 resulted in the escape of at least ten alien fish species that were recorded for the first time, from the natural waters of the Western Ghats. Illegal farming systems, aqua-tourism destinations and amusement parks, as well as reservoirs, facilitated the escape of alien species during the events. Despite expanding invasions, unmanaged stocking and aquaculture using alien species continue in the Western Ghats, necessitating urgent management and policy interventions.

Smrithy Raj, lead author of the paper and a PhD student working on alien species at the university, has said, “In India, there are no specific policies to address the issue of invasive alien species, though it is part of several existing biodiversity legislation and regulations.”

The National Biodiversity Strategy and Action Plan published in 2014 has several suggestions for the regulation of the introduction of invasive alien species and their management but none of the suggestions is put into practice; besides, there is no national mechanism or an institutional mechanism to foresee and enforce this, said Raj. The researchers call for monitoring tools such as environmental DNA to keep tabs on these hardy non-native species in Indian waters.

Gaps also remain in the countrywide assessment of impacts of such invasive alien species on the economy, biodiversity and food security. There is a need to better understand the factors that trigger alien species to become invasive and pathways of introduction to natural ecosystems, and for strict enforcement of environmental laws and awareness among local communities, experts said.

Invasive alien species are species that are introduced, accidentally or intentionally, outside of their natural geographic range and that become problematic, states the International Union of Conservation of Nature. For a species to become invasive, it must successfully out-compete native organisms for food and habitat, spread through its new environment, increase its population and harm ecosystems in its introduced range, states the Convention on Biological Diversity (CBD).

High magnitude floods in August 2018 and 2019 resulted in the escape of at least ten alien fish species that were recorded for the first time in the water bodies and rivers snaking through the Western Ghats following the floods. Illegal farming systems, aqua-tourism destinations and amusement parks, and reservoirs facilitated the escape of alien species.

Last year, the appearance of three exotic whiteflies within a span of two years in India’s coconut plantations had led to the Central Plantation Crops Research Institute (CPCRI) scientists sounding a warning bell on the increased bio-security risks arising from the uncontrolled exchange of plant material. As a Mongabay-India report points out, first reported in Central America 2004 and then in the United States, the rugose spiraling whitefly, an invasive alien insect pest, was quietly siphoning out the sap from coconut palms in southern states of India in 2016, as they reeled under a prolonged dry spell.

The rampage of the two millimetre-long whitefly, a sap-feeding bug, was subsequently subdued by its natural enemies. Two years later, in December 2018, after the devastating Kerala floods, two tinier whitefly species, also invasive, had displaced their predecessor, scientists said in a study.