Temperature, light, direction of currents and selected water quality parameters at coral reef sites within Talang-Satang MPS

Coral reefs around the world are being increasingly threatened by the increase in sea water temperature. Therefore Temperature / Light logger and G Acceleration Logger were deployed to record temperature, light intensity and direction of current flow every twenty minutes for eight months at west of Pulau Talang Talang Besar, Sarawak. Other selected water quality parameters were also recorded at four stations within Talang- Satang MPA. Three regimes, Regime A, Regime B and Regime C each corresponding to the Southwest monsoon (May to September), intermonsoon (September to November) and Northeast monsoon (November to March) was distinguished based on the tidal cycle and large changes in direction of current during intermonsoon. Temperature and light intensity were found to decrease as the monsoon changes from Southwest monsoon to Northeast monsoon. The direction of current was found to have the highest variability during intermonsoon and the velocity of current was higher during monsoon seasons, corresponding to the larger change in hydrodynamics of the water column. It was also found that there was a positive correlation between light intensity and temperature throughout the eight months. Temperatures as high as 31.3˚C were recorded during Southwest monsoon (July to September). High water temperatures from 30.8˚C to 31.3˚C were recorded for 23 days and change in 1.0˚C of water temperature in a day was recorded during Northeast monsoon (November to March). The overall water quality of Talang-Satang MPA was found to be suitable for healthy coral reefs and there was no significant change in water quality between the two surveys (July 2011 and April 2012)

Bacterial communities of talang-talang reef and their potential role in coral defense

Complex microbial communities are known to have significant influence over coral reef ecosystems. The Talang-Satang region is situated off the coast of Sematan and is especially important as it is one of the most diverse ecosystems found off Sarawak. Interestingly, the Talang-talang reef thrives at above-average temperatures of 28-30 °C throughout the year. Through isolation and identification (16S rDNA) of native microbes from the coral, surface mucus layer (SML), as well as the surrounding sediment and waters, we were able to determine the species composition and abundance of the ctilturable bacteria in the coral reef ecosystem. Isolates found attached to the coral are mostly related to Vibrio spp., presumably attached to the mucus from the water column and surrounding sediment. Pathogenic Vibrio spp. and Bacillus spp. were dominant amongst the isolates from the water column and sediment. Known coral pathogens responsible for coral bleaching, V. coralliilyticus and V. shilonii, were isolated from the coral SML and sediment samples respectively. Coral SML isolates are found to be closely related to known nitrogen fixers and antibiotic producers with tolerance towards elevated temperatures and heavy metal contamination. The presence of type I modular polyketides synthase (PKS) genes responsible for clinical and economical macrolide polyketides production, and non-ribosomal peptide synthetase (NRPS) genes with the ability to produce immunosuppressant cyclosporine and other antibiotics were screened using specific PKS and NRPS primers. This specialized microbiota may be important for protecting the corals from pathogens by occupying entry niches and/ or through the production of secondary metabolites (i.e. antibiotics). The community from the coral SML were tested against each other at 28, 30 and 32 °C, and were found to exhibit antimicrobial properties under normal temperatures while pathogenic strains appear more toxic at elevated temperatures. Our results highlight the potential of bacteria associated with the coral SML in producing antibiotics and also indicate their important role in the coral defence

Holocene relative sea-level records from coral microatolls in Western Borneo, South China Sea

The spatial variability of Holocene relative sea level (RSL) in the South China Sea is unknown, with data restricted to Thailand, the Malay Peninsula, and a few other isolated sites. In this study, we present new continuous RSL records for Borneo using surveyed and U–Th dated coral microatolls from four sites in western Sarawak. The record spans 450 years of RSL from 7450 to 7000 yr BP. Our data suggest that RSL was higher than present and rapid RSL rise had ceased by 7450 yr BP. We compare these RSL reconstructions with a regional model of glacial-isostatic adjustment (GIA). The RSL reconstructions from three sites off the coast of Sarawak show a spatial gradient opposite to that predicted by the GIA model. This disagreement can best be explained by tectonic deformation since 7000 yr BP, which was previously unrecognized. We propose vertical land motion of 0.7–1.45 m due to slip on the Serabang fault, which runs between our four sites. This slip may have occurred in response to the loading of the Sunda Shelf by rising sea level.NRF (Natl Research Foundation, S’pore)Published versio