Coral reefs substrate composition influence on nudibranch diversity

Abstract

Abstract The substrate serves as a habitat and a source of food for Nudibranch. Therefore, it influences the existence of nudibranchs. This study examined the differences in the presence of nudibranchs at two locations with different substrate compositions on Lembeh Island and a flat island (Tunda Island). Data collection used a modified belt transect 50m long and 4m wide (200m2) with a depth of 5-7m along the coastline. A total of 86 individual specimens consisted of 12 families with 22 species were recorded. The largest group was the Phyllidiidae family (10 species). Chromodorididae and Polyceridae family represented by 3 species each, Facelinidae family represented by 2 species, and Dotidae, Flabellinidae, Discodorididae, and Myrrhinidae, each represented by one species. Nudibranch diversity was higher on Lembeh Island than Tunda Island. A total of 19 species were found on Lembeh Island while only 5 species were found on Tunda Island. The wealth of nudibranch is largely determined by the composition of the substrate. Based on hierarchical analysis 80.93% of determinants of nudibranch existence was a substrate category of DCA, sponges, and hard corals. Nudibranch’s diversity directly proportional to the percentage of DCA and sponge, and inversely proportional to the percentage of hard coral.