Reproduksi seksual karang (ordo Scleractinia): pemijahan, perkembangan larva dan metamorfosa

Abstract

Coral reef damage was exacerbated in several parts of Indonesia and only had 70% in good and very good conditions remaining. Destructive fishing and exploitation of ornamental corals have added to the scarcity of coral species. As a result the distance between the colonies of the species can inhibit the further reproduction between the colonies. However, the information pattern and timing of reproduction in natural coral is still limited, and reproduction efforts in exsitu methods were still in the research scale. This research was carried out at two separate locations namely Spermonde Archipelago and the Great Barrier Reef and was aimed to : (a) compare the pattern and timing of coral reproduction in Spermonde Archipelago Indonesia and in Orpheus Island of Great Barrier Reef Australia, (b) know the response time of spawning and spawning behavior of coral polyps caused by induction of spawning, (c) compare the fertilization, embryo development, competence time of species, (e) determine the appropriate light intensity, substrate position, CCA and zooxanthellae induction for larvae settlement, juveniles attachment dan metamorphosis of planula larvae. The results were coral reproduction pattern of small polyp corals were performed during rainy season but the bigger polyps were in dry seasons in Spermonde, while in the GBR was held in November and December during early summer. Synchronous broadcast spawning took place at 18:00–19:00 in lunar period 0 – 2 days AFM, while the high tide in Spermonde. Otherwise, multispecies mass spawning in GBR took place at 19:00-21:.00 for 3-5 AFM in the low tides. The water flow and strong aeration provided for A. tenuis was spawned earlier more than one hour than natural spawning. The same pattern of inter-species fertilization rate, more than 95% fertilization were achieved in less than 4 hours. In addition, the development of embryos and larvae were significantly differed between two species, i.e. embryos and larvae A.millepora grew faster than A.tenuis while Ctenactis crassa was faster than Fungia concina. Furthermore, the competence time of Acroporidae was longer than Fungiidae. Planulae larvae and juveniles of A. tenuis much more settled and attached while in higher light intensities of 130-170 μmol/m2/s. However, light intensity did not affect the total deposition of larvae and juveniles settled. Juveniles prefer attached at the horizontal substrate were significantly much more than those at vertical substrate. Induction of zooxanthellae and CCA separately could affect metamorphosis significantly. Larval metamorphosis of A. tenuis showed the same response to different concentrations of zooxanthella.