Seagrass ecosystems of Ritche’s Archipelago in the Andaman Sea harbor ‘Endangered’ Holothuria scabra Jaeger, 1833 and ‘Vulnerable’ Actinopyga mauritiana (Quoy & Gaimard, 1834) sea cucumber species (Echinodermata: Holothuroidea)

Abstract

This study reports the presence of ‘Endangered’ sea cucumber Holothuria scabra for the first time from the mixed seagrasses of Havelock Island, and the ‘Vulnerable’ Actinopyga mauritiana from the monospecific Thalassia hemprichii meadows from Neil Island of Ritche’s Archipelago of Andaman & Nicobar Islands (ANI). Both species were found during field survey of intertidal seagrass ecosystems of Ritche’s Archipelago. Morphometric measurements were carried out in the field using a vernier caliper, and identification was confirmed using the identification guide for sea cucumbers of ANI provided by the Zoological Survey of India. The total body length of the H. scabra specimen was 15.7 cm, mouth width of 3.2 cm and body circumference of 5.7 cm. The specimen was a juvenile, grey in color with a total of 17 black and yellow transverse stripes along the body. The average body length of A. mauritiana specimens examined differed between those from seagrass meadows (20.4 cm) non-seagrass areas (15.7 cm) as did mouth width and total circumference. Mono and mixed seagrass meadows of ANI are critical habitats for sea cucumbers and require monitoring and protection for conservation of declining populations.