The Shallow-water Macro Echinoderm Fauna of Nha Trang Bay (Vietnam): Status at the Onset of Protection of Habitats

Abstract

Hon Mun Marine Protected Area, in Nha Trang Bay (South Central Vietnam) was established in 2002. In the first period after protection had been initiated, a baseline survey on the shallow-water macro echinoderm fauna was conducted. Reefs in the bay were surveyed by transects and free-swimming observations, over an area of about 6450 m2. The main area focused on was the core zone of the marine reserve, where fishing and harvesting is prohibited. Abundances, body sizes, microhabitat preferences and spatial patterns in distribution for the different species were analysed. A total of 32 different macro echinoderm taxa was recorded (7 crinoids, 9 asteroids, 7 echinoids and 8 holothurians). Reefs surveyed were dominated by the locally very abundant and widely distributed sea urchin Diadema setosum (Leske), which comprised 74% of all specimens counted. Most species were low in numbers, and showed high degree of smallscale spatial variation. Commercially valuable species of sea cucumbers and sea urchins were nearly absent from the reefs. Species inventories of shallow-water asteroids and echinoids in the South China Sea were analysed. The results indicate that the waters of Nha Trang have echinoid and asteroid fauna quite similar to that of the Spratly archipelago. Comparable pristine areas can thus be expected to be found around the offshore islands in the open parts of the South China Sea. The effects of echinoderms on the reefs, impacts from humans on the echinoderms and possible effects from protection of habitats are evaluated.