Coral community response to bleaching on a highly disturbed reef

While many studies of coral bleaching report on broad, regional scale responses, fewer examine variation in susceptibility among coral taxa and changes in community structure, before, during and after bleaching on individual reefs. Here we report in detail on the response to bleaching by a coral community on a highly disturbed reef site south of mainland Singapore before, during and after a major thermal anomaly in 2010. To estimate the capacity for resistance to thermal stress, we report on: a) overall bleaching severity during and after the event, b) differences in bleaching susceptibility among taxa during the event, and c) changes in coral community structure one year before and after bleaching. Approximately two thirds of colonies bleached, however, post-bleaching recovery was quite rapid and, importantly, coral taxa that are usually highly susceptible were relatively unaffected. Although total coral cover declined, there was no significant change in coral taxonomic community structure before and after bleaching. Several factors may have contributed to the overall high resistance of corals at this site including Symbiodinium affiliation, turbidity and heterotrophy. Our results suggest that, despite experiencing chronic anthropogenic disturbances, turbid shallow reef communities may be remarkably resilient to acute thermal stress

Skeletal growth rates in porites lutea corals from pulau tinggi, Malaysia

10.3390/w14010038Water (Switzerland)14138-3

Multi-colony calibration of barium isotopes between shallow-water coral skeletons and in-situ seawater: Implications for paleo proxies

Barium incorporated in coral skeletons has been widely used as paleo proxies to study terrestrial inputs, upwelling and anthropogenic activities in marine environments. However, these applications often face the challenges of poor replication in the coral skeletal Ba/Ca records from multiple coral colonies and complex Ba sources in coastal environments. Recent studies of Ba isotopes in seawater and deep-sea corals have demonstrated the potential to trace Ba sources and water mixing in the ocean, but there is still a lack of calibrations for Ba isotopes in shallow-water corals. In this study, we present the first multi-colony Ba isotope calibration from three shallow-water Porites lutea corals with the contemporaneous in-situ seawater data from the Singapore Strait. We also report the Ba isotope data in the regional water masses around the study area (e.g. South China Sea, Malacca Strait and Johor River estuary). Singapore water Ba concentrations and isotope compositions show a strong influence of terrestrial inputs, following seasonal salinity and monsoon-driven water-mass mixing between the Malacca Strait and the South China Sea. The coral skeletal δ138/134Ba results are generally consistent between the three coral colonies and time-series data closely follow the seasonal δ138/134Ba variations in seawater. Despite the partition coefficient of Ba having a large uncertainty (DBa = 0.91 ± 0.29), the Ba isotope fractionation between the coral skeletons and seawater is relatively constant (Δ138/134Bacoral-sw = -0.28 ± 0.06 ‰) and shows no significant difference between these corals. The mechanism controlling Ba incorporation and isotope fractionation in coral skeletons remains unclear, but the evidence clearly indicates that the coral skeletal Ba is originated from dissolved Ba in seawater. The constant offset of Ba isotopes between coral skeletons and seawater allows for reliable records of seawater δ138/134Ba values. Ba isotopes in coral skeletons could be used to reconstruct surface water salinity variability in the Singapore Strait, reflecting monsoon driven changes in regional water mass mixing.Royal Society Commonwealth Science Conference Fellow-on Grant (CSC\R1\170048) and the National Research Foundation Singapore (Marine Science Research and Development Programme project P03

Sub-annual fluorescence measurements of coral skeleton: relationship between skeletal luminescence and terrestrial humic-like substances

10.1007/s00338-020-01959-xCoral Reef

Scleractinian coral (Cnidaria, Hexacorallia, Scleractinia) diversity of the Mersing Islands, Peninsular Malaysia

10.3897/zookeys.1102.82228ZooKeys20221102177-19

Luminescence and density banding patterns in massive <em>Porites </em>corals around the Thai-Malay Peninsula, Southeast Asia

We characterized the annual luminescent and skeletal density banding patterns in 51 massive Porites corals from 15 reefs from six locations around the Thai-Malay Peninsula in Southeast Asia, and explored the seasonal environmental cues/drivers of band formation. Location-specific recurrent annual luminescent banding patterns were found at all study locations with a brighter band occurring toward the end of the year (∼October/November/December) (at five locations) and in ∼June (one location). Annual density banding patterns could only be discerned at four locations, and were categorized into those that formed a dense band commencing ∼November/December, and those starting ∼May/June. Overall, compared to luminescence, variations in skeletal density provided a less clear signal for demarcation of annual growth increments. Seasonal variations in luminescence showed clearest relationships with salinity, as a proxy for freshwater/river runoff. No convincing relationship between intra-annual luminescence intensity and density variations was found, which supports the notion that luminescent banding is due to inclusions of fluorophores into the coral skeleton rather than variations in skeletal architecture. The relationships between seasonal density variations and significant wave height and rainfall suggest density banding in this region is likely related to wave energy, or some other correlated environmental parameter/s. The large variability in skeletal banding patterns not only highlights the current relatively poor understanding of their nature and causes, but also the need for replication in their interpretation, especially in settings with complex seasonal hydrodynamic/hydrological patterns such as those found around the Thai-Malay Peninsula

Coral Growth and Bioerosion of Porites lutea in Response to Large Amplitude Internal Waves

The Similan Islands (Thailand) in the Andaman Sea are exposed to large amplitude internal waves (LAIW), as evidenced by i.a. abrupt fluctuations in temperature of up to 10uC at supertidal frequencies. Although LAIW have been shown to affect coral composition and framework development in shallow waters, the role of LAIW on coral growth is so far unknown. We carried out a long-term transplant experiment with live nubbins and skeleton slabs of the dominating coral Porites lutea to assess the net growth and bioerosion in LAIW-exposed and LAIW-protected waters. Depth-related, seasonal and interannual differences in LAIW-intensities on the exposed western sides of the islands allowed us to separate the effect of LAIW from other possible factors (e.g. monsoon) affecting the corals. Coral growth and bioerosion were inversely related to LAIW intensity, and positively related to coral framework development. Accretion rates of calcareous fouling organisms on the slabs were negligible compared to bioerosion, reflecting the lack of a true carbonate framework on the exposed W faces of the Similan Islands. Our findings show that LAIW may play an important, yet so far overlooked, role in controlling coral growth in tropical waters