Progress report for
Coastal Habitat Rehabilitation in Gulf of Mannar, Tamil Nadu, India
Achievement at a glance
The rehabilitated coral and seagrass sites in Koswari Island of Gulf of Mannar were continuously monitored from December 2016 and results are provided up to March 2019. The average survival of the coral transplants was 83.16%. Turbinaria mesenterina had the highest survival (93.65%) followed by Acropora intermedia (87.25%). The growth rate was the highest in Acropora intermedia (36.72 cm) followed by Acropora cytherea (34.03) cm during the period between December 2016 and March 2019. The overall coral recruit density was 1.59 no/module and the density was highest for the genus Acropora (0.52 no/module). A total of 5,877 fishes were counted up to March 2019. Abudefduf sp. and Lutjanus sp. are the dominant fish species. The overall macrofauna density in March 2019 was 18.22 5m-2. Live coral cover in Koswari Island was 27.32% in 2015 and it declined to 17.56% in 2016 due to bleaching and subsequent mortality. At present, live coral cover increased to 20.06% in March 2019 and the area cover of restored reef with coral recruits increased to 2.4 sq km.Seagrass percentage cover increased from 15.1 (Dec 2016) to 46.7% (Mar 2019). The overall shoot density increased from 67.5 to 217.8 m-2 with the highest value for Cymodocea serrulata at 96.95 m-2 during March 2019. The respective values for Thalassia hemprichii and Syringodium isoetifolium are 77.1 and 43.8 5m-2. A total of 2,051 fishes were counted at the seagrass restoration sites. Sardinella sp. and Stolephorus commersonnii were the dominant fish species at the seagrass restoration sites. The overall density of macrofauna during March 2019 at seagrass rehabilitation sites was 62.07 5m-2. The area cover of restored seagrass increased to 2.6 sq km during the study period.
In addition to monitoring, regular maintenance is also in progress in the rehabilitation sites.
Challenges faced in implementation
The major challenges are 1). The disturbances to the rehabilitation sites (in spite of their being within Marine National Park) by small-scale fisher folk who use gill nets. The fishing practices dislodge and break the rehabilitated corals and disturb seagrass transplants; 2). Alga on the substrates covers the coral transplants in rehabilitation sites; and coral bleaching due to climate change caused elevated temperature.However, the above said threats are addressed in time through regular monitoring and maintenance. As a part of maintenance, the dislodged and broken coral fragments and disturbed seagrass shoots are replaced, the algae grown on the rehabilitation substrates are removed and cleaned, and the bleached coral transplants are replaced if there is mortality.
Beneficiaries
The main beneficiaries are the poor local small-scale fishers, who will benefit through increased fish catch for their livelihood. The increase of coral and seagrass cover will also help the associated biodiversity and hence there will be benefit to researchers, conservation managers and Government, who have taken efforts to preserve the unique biodiversity from climatic and non-climatic impacts. The healthy coral and seagrass cover will also benefit in the reduction of coastal erosion.
Actions
The beneficiaries in particular the fisher folk are informed of the benefit of coral and seagrass rehabilitation in fish production and other environmental benefits through awareness building programs. The youths of the fishing community are trained in rehabilitation and monitoring techniques to help researchers. The conservation managers and field staff are trained in monitoring the rehabilitated sites to collect data and to take remedial measures. The policy-makers are informed through reports and workshops, while researchers are informed through research publications and workshops.Coral and seagrass rehabilitation has been given high priority by the Government as an iimproved adaptation measure to fight the impacts of climate change so as to enhance live coral and seagrass cover for restoring ecological services.