Marine debris with high buoyancy, such as bottles, rubber, household items, and plastic bags, carries along with it a large number of invasive species to the Indian shores, thus becoming a new source of threat to the livelihood of the locals, including fishermen already grappling with climate change impacts, overexploitation, sewage, and unregulated tourism, among others.”
The research published recently in Marine Pollution Bulletin by a team of Indian and foreign researchers while conducting a study in the southeast coast of India highlighted the threat that looms large on the Indian coastline of 7,516 km of which the mainland accounts for 5,422 km. Nearly 250 million Indians live within a distance of 50 km from the coastal areas of India.
“The results highlight the increasing risk of invasive species colonisation on plastics along the southeast coast of India. This is particularly worrying at a time when plastics are becoming a more and more common substrate for marine organisms, especially in India, which is one of the top countries contributing most to ocean plastic pollution. “Our study thus serves as a call to immediate action to address plastic pollution and its related threats in India.” explains Dr Blanca Figuerola, a member of the Medrecover Group and the last author of the study.
The research team, led by the Institut de Ciències del Mar (ICM-CSIC) and the Sathyabama Institute of Science and Technology in collaboration with the University of Barcelona (UB), the Abdelmalek Essaadi University (UAE), and the University of Oslo (UiO), had conducted a comprehensive examination of fouling organisms on various types of stranded litter, including plastic, glass, rubber, foam sponge, cloth, metal, and wood. They found a total of 3,130 specimens/colonies belonging to seven phyla and representing 17 species stuck on these litters.
For instance, invasive mussel Mytella strigata was found attached in high density groups to fishing nets. “This discovery emphasises the significant role of marine litter in facilitating the spread of invasive species, potentially disrupting the ecological balance of Indian waters,” explained Dr Gunasekaran Kannan, the first author of the study. “Litter items with high buoyancy, such as bottles, buoys and plastic bags supported abundant macroinvertebrate assemblages, suggesting the potential for long distance transport,” pointed out Dr Kannan.
Among the most commonly found organisms associated with marine litter were the cosmopolitan bryozoans Jellyella tuberculata and J eburnea, the barnacles Lepas anserifera, Amphibalanus amphitrite, and Amphibalanus sp., and the oysters Saccostrea cucullata and Magallana bilineata. The IUCN in a report observed marine invasive species as one of the most “insidious threat”. Alien species can be transported by various means: in ship ballast water or by attaching to hulls, as ‘hitchhikers’ clinging to scuba gear or packaging, as consignments of live organisms traded to provide live bait or gourmet food and as pathogens, carried by other organisms.
An estimated 7,000 species are carried around the world in ballast water every day. The invasive alien species means reductions or complete collapse in fisheries production due to competition, predation and displacement of the commercially important fish species through invasion, say the experts. According to yet another report, invasive species with adverse impacts globally such as water hyacinth and fish species common carp are posing a threat to native species in the coastal state of Kerala. Overall, India has lost $127.3 billion (`8.3 trillion) in the last 60 years to as many as 10 invasive alien species (IAS), out of 330 that are known to be invasive in India, making the South Asian nation the second most invasive-cost bearing country after the United States.
Researchers said simple tweaks to national policies and setting up institutions to exclusively deal with invasive species as a biosecurity issue, both from research and management perspectives, would go a long way. “The negative economic impacts are documented and available only for 3 per cent of the known invasive species and unavailable/masked/underrepresented for the rest 97 per cent of invasive species in India. That’s a huge knowledge gap,” evolutionary biologist Alok Bang said in a report.
“Based on this global analysis, going by India’s GDP, we must have spent about $3.4 trillion on invasive species in the last six decades; going by India’s population, we must have spent about $1,700 trillion in the last six decades,” Bang said as per the report. Dr Anna Sanchez-Vidal, Associate Professor in the UB Department of Earth and Ocean Dynamics, member of the UB’s Marine Geosciences Consolidated Research Group and co-author of the study published in the Marine Pollution Bulletin too called for effective waste prevention and management, education, and awareness campaigns to mitigate the introduction of invasive species via marine litter. Local and global stakeholders must come together to address this critical issue and protect the fragile marine ecosystems along India’s southeast coast, he opined.
The team has already warned that plastic debris in the sea was contributing to the introduction and transport of non-native marine species in the Catalan coast in a recent study. Coastal areas are already facing pressures such as climate change, overexploitation, sewage, nutrient pollution and recreation activities which can exacerbate the impacts of invasive non-native species, as per experts.