Mapping sites of reef vulnerability along lagoons of Lakshadweep archipelago, Indian Ocean

Tissue degradation and mediated mortality have turned into a major threat to coral reef systems around the world. Detailed knowledge on interactions of prime biological factors that mediate tissue loss and mortality is of paramount importance in understanding the prevailing reef health scenario and to trial management actions. In the present study, a series of benthic surveys were conducted in Lakshadweep islands to understand the interactions of plausible biological factors in causing tissue loss and mediated mortality. Interactions of biological scenarios were prioritized using hierarchical regression analysis. The hierarchical regression model analysis revealed black band disease (β = 0.59; p < 0.001) and algal interactions (β = 0.48; p < 0.001) as the major factors responsible for tissue-loss-mediated coral mortality in the region. The observations from the hierarchical analysis were used to derive vulnerability maps based on weighted overlay analysis. The vulnerability mapping revealed that lagoon of Kalpeni Island is very highly vulnerable to coral degradation with 683.5 ha followed by Kavaratti (70.2 ha), Bangaram (70 ha), and Amini (47 ha). Chethalath and Agatti lagoons were inferred as low vulnerable sites where coral reefs can sustain. The vulnerability maps derived can be used as a baseline observation to identify areas of very high vulnerability and specific stressor prevalent in those sites. This will be helpful in defining stressor and site-specific management plans.