Status of health and conservation classification of tropical coral reefs in Lakshadweep archipelago

Abstract

Coral reefs of Lakshadweep perform a range of vital ecosystem functions and sustain the livelihoods of island communities. Coral reefs provide ecosystem services that are vital to human societies and industries through fisheries, coastal protection and tourism. The present study was undertaken during September and October 2015 to assess the status of reef health in 10 inhabited Islands of Lakshadweep following reef classification to imply conservation measures and also for the sustainable management by the dependent communities. Live coral cover, habitat complexity index, coral species richness, reef condition index, mortality index, morphological dominance, morphological diversity and coral conservation class were used to get an aggregate value of ‘composite condition’ index for determining the overall conservation values of coral reefs in these Islands. Kadmat reef had the highest live coral cover of 64.50% among the 10 inhabited islands. Bitra and Kiltan reef had good live coral cover of 62.75 and 52.25% respectively. The major benthic component in all the studied islands is live coral except in Amini and Andrott Islands. The recovery of corals has increased significantly in the last 5 years in Kadmat, Bitra, Kiltan and Bangarm after the 2010 mass bleaching event. Among the eight attributes, significant positive correlations were found between coral reef condition and live coral cover (r = 0.93, p < 0.05), between coral species richness and coral reef condition (r = 0.69, p < 0.05), between habitat complexity and morphological dominance (r = 0.68, p < 0.05) and between habitat complexity and conservation class (r = 0.72, p < 0.05). Coral morphologies (traits) were considered to determine the structural complexity of reefs. Based on r-K-S ternary diagram, coral morphology classification conservation class 1 (CC1) was assigned to the reef sites in Amini, Bitra and Chetlat which had > 60% of stress tolerators. CC3 was assigned to Bangaram and Kadmat due to the presence of > 75% of ruderals. Mixed coral morphology was recorded in Agatti, Andrott, Kalpeni, Kavaratti, and Kiltan with approximately equal proportions of ruderals, competitors and stress tolerators, and these coral reefs were designated as CC4. Protection and conservation management measures, as well as sustainable resource use, have been suggested based on the live coral cover, conservation class, and coral reef health status.