DENSITY AND POPULATION GROWTH OF THE BLACK SEA CUCUMBER, HOLOTHURIA (HALODEIMA) ATRA (JAEGER, 1833) IN TWO DIFFERENT MICROHABITATS OF JEPARA WATERS, INDONESIARetno Hartati, Muhammad Zainuri, Ambariyanto Ambariyanto, Ita Riniatsih, Hadi Endrawati, Sri Redjeki, Ria AT Nuraini, Agoes Soegianto and Sekar Widyaningsih
A year study on the density and population growth parameters of the sea cucumber Holothuria (Halodeima) atra (Jaeger, 1833) of two microhabitats (seagrass meadow and rubble with macroalgae) were carried out in Jepara waters, Indonesia. A Complete enumeration or total sampling was applied in which the samples of sea cucumber were counted, measured for their length then put them back in their habitat. The population parameters were determined using FISAT II. The population of H. atra was found all year-round (October 2017 to October 2018) in seagrass meadow habitat, but only found during October 2017 up to April 2018 in the rubble with macroalgae habitat with a mean density of 0.047Â±0.012 indv.m-2 and 0.044 Â±0.024 indv.m-2 respectively. Sea cucumber total length varied from 3 to 40.53 cm and 9.31-42.87 cm in seagrass and rubble habitat, with uni-modal and up to three-modal distribution. The growth parameters were Lâ 40.95 and 44.10 cm in both microhabitats. Individual growth coefficient (K) and the theoretical age at zero-length (to) in seagrass and rubble habitat were 1.11; -0.805 and 2.1; -0.403 respectively. Although there has been very little sea cucumber catch fisheries in the area, the density tends to decline. The asexual reproduction by fission of H. atra showed to produce small individual which gave effect to populations growth in seagrass meadow but not in the rubble with macroalgae habitat.