Progress report for
Removal of marine debris from reef areas in Gulf of Mannar, Tamil Nadu, India - to reduce the stress to the bleached corals and to support recovery process
Achievement at a glance
Corals in Gulf of Mannar, Southern India, are distributed around the 21 uninhabited islands located within the Marine National Park and stretching 160 km along the coast between Rameswaram and Tuticorin. Fishing in the reef areas has caused considerable damage to corals. Underwater survey was conducted by SDMRI to assess the accumulation and impact of marine debris. The derelict nets and other debris including plastics, ropes, lines and traps pose severe threat to the already stressed corals. About 1,152 m2 reef area is affected and Tuticorin Group of islands tops the list with an affected area cover of 548 m2. 43% of the total debris is made of fishing nets. The debris affects live corals (39%), Dead coral with algae (36%) and Dead coral (25%). Branching and massive corals are the most affected types. The categories of damages are: Fragmentation (FR), Tissue Loss (TL), and Coral Mortality considered as Dead Coral (DC). Slow but steady post-bleaching recovery of corals was recorded in 2017 and 2018 but new recruits in large numbers were also found affected by the derelict nets.Coral rehabilitation has been carried out in Gulf of Mannar by SDMRI since 2002. The rehabilitation sites at Tuticorin coast too are contaminated with plastics, ropes, lines and abandoned fishing nets. Of them, fishing nets constitute the major threat (66%). In the rehabilitation sites branching and table corals are the most affected coral types, with the damages falling mostly in the categories of fragmentation and coral mortality.
SDMRI is involved in the removal of marine debris from the natural and rehabilitated coral areas. A team of eight reef researchers are engaged in this task in order to reduce stress to the bleached corals and also to support the recovery.
The efforts to remove the marine debris are in progress.
Challenges faced in implementation
The major challenges encountered are 1). Removal of nets requires the services of professional divers as the nets have to be carefully taken off the corals without any damage; 2). The reef area is vast and corals are distributed along 160 km long coast; 3). The process involves considerable budget; and 4). Favourable climatic conditions with clam seas prevail only during October to March in Gulf of Mannar.The other important challenge is that fisher folk continue to fish in reef areas, though the reef areas are coming under Marine National Park.
Beneficiaries
The removal will benefit the growth and health of reefs, which will in turn help the poor local small-scale fishers with increased fish catch for their livelihood. After the coral bleaching and subsequent mortality in 2016, at present there is slow recovery and the removal of debris will help to reduce stress and support the recovery. The protection of reefs from these ghost nets will also support in protecting the associated biodiversity. The healthy corals and seagrass will also facilitate the reduction of coastal erosion.
Actions
SDMRI is involved in the removal of marine debris from the natural and rehabilitated coral areas. A team of eight reef researchers are engaged in this task in order to reduce stress to the bleached corals and also to support the recovery.The fisher folk are informed of the impact of ghost nets on coral reefs and associated biodiversity, thus making them self-motivated to avoid reef areas while fishing. The conservation managers and policy-makers are informed through reports about the progress of work while researchers are informed through research publications and workshops.