Long-term benefits of artificial reef modules for reef recovery in gulf of Mannar, Southeast India

Abstract

The Gulf of Mannar (GoM) in southeastern India, once well known for its rich coral reefs, has been suffering for a long time from the vagaries of unprecedented threats posed by many natural and human-induced factors. The deployment of low-tech, low-cost artificial reef (AR) modules made of ferro-cement near Vaan Island in GoM helped enhance fishery production and enrich biodiversity. These modules remain strong even at the end of 15 years and continue to provide substrata to a significantly large population of coral colonies. In 2017, the density of the coral colonies attached to the ARs was found to be as high as 25.45 numbers per module (No.module−1). Recruits from 13 genera were observed on the modules, Turbinaria (5.4 No.module−1) and Favites (4.87 No.module−1) being the dominant genera. The modules have attracted the recruits of boulder type corals, which are important for long-term ecological services. Widespread deployment of these modules would aid in reef recovery by providing suitable substrate for coral recruits.