Diversity of Echinoderms in Intertidal and Shallow-water Areas of Samal Island, Philippines

Abstract

Echinoderms are immediately observable around the coastal shores of Samal Island. Unfortunately, studies on echinoderm diversity are lacking despite its relevance to coastal and marine ecosystems management. This study attempts to update the existing records of echinoderms in Samal Island, however, limited to the intertidal and shallow-water areas. Field surveys from January 2018 to January 2019 yielded a total of 30 echinoderm species belonging to 17 families. Most of the echinoderms encountered belonged to Classes Asteroidea (sea stars, nine species) and Ophiuroidea (brittle stars, nine species), followed by Echinoidea (regular and irregular urchins, six species) and Holothuroidea (sea cucumbers, six species). Of the 1,015 individuals, sea urchins comprised the majority of the total individuals recorded (43.15%), succeeded by sea stars (30.44%), brittle stars (18.04%), and sea cucumbers (8.37%). Richest diversity was observed in Catagman with 23 echinoderm species recorded. This was followed by Camudmud (14 species), Pangubatan (eight species), Balet (seven species), Aundanao (six species), and Kaputian (three species). The five most commonly occurring species were the Echinometra mathaei (Blainville, 1825), Archaster typicus (Müller and Troschel, 1840), Ophiocoma scolopendrina (Lamarck, 1816), Diadema setosum (Leske, 1778), and Linckia laevigata (Linnaeus, 1758). Differences in distribution and abundance may be attributed to the variability of habitats available across sites. An intensive biodiversity assessment is recommended to evaluate how the physicochemical parameters and extent of anthropogenic activities shape the diversity and distribution of echinoderms on the island. The current work also provides the first documentation of ophiuroid diversity and the first record of the brittle stars, Breviturma krohi (Stöhr, Boissin & Hoareau, 2013) and Ophiocoma cf. cynthiae (BenavidesSerrato and O’Hara, 2008) in Samal Island, Philippines.