Scleractinian recruits on natural and artificial substrates in temporary sediment-challenged coastal water of Bangkalan, Madura Island, Indonesia

Abstract

Recruitment of coral juveniles could serve as indicator for potential of coral reef recovery and is a critical process in supporting population as well as facilitating recovery after event of disturbance. However, sediments suspended in the water column and settling on to reef surface can negatively influence the distributions and abundances of reef-building corals, including altering the settlement patterns and survival of coral larvae and new recruits. In this study, we compared the density and diversity of Scleractinian recruits on natural substrate and artificial reef (made of concrete; 2 years after deployment) in the relatively turbid water of Sepulu coastal water, Bangkalan - Madura Island, East Java. Observation of stony coral recruits were conducted in-situ at depth of 3-4 meter in two locations. At the end of the study, we identified 18 species of Scleractinians from 10 genera and 7 families; dominated by Goniopora (F. Poritidae), Galaxea (F. Euphyllidae) and Goniastrea (F. Merulinidae). There was no difference in term of species richness and composition among locations and type of substrate. However, in both locations, more recruits grown in concrete artificial reef (15.2±2.61 - 18.3±2.91 unit/m2) compared to natural substrate (4±1.25 - 4.1±1.29 unit/m2), respectively. These findings suggest that concrete artificial reef is applicable for coral reef restoration and rehabilitation in temporary turbid coastal water by providing suitable substrate for larval recruitments.