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Decades of coastal urbanisation have replaced many natural shorelines with seawalls. Marine communities have been documented on these replacement habitats, but little is known about the effects of seawall inclination on the diversity and depth distribution of sessile organisms on this artificial substrate. Surveys of hard coral and other sessile communities in Singapore indicated that benthic communities at the deeper zone (− 2 m chart datum) were significantly different between three sloping (about 33° inclination) and three vertical seawalls of similar age. Hard coral communities were significantly different between sloping and vertical seawalls and between 0 m chart datum and − 2 m chart datum. Hard coral communities on sloping seawalls were also significantly more diverse than on vertical seawalls. At both depths, sloping seawalls were dominated by abiota with hard coral comprising appr. 17% of the total surface, while vertical seawalls were dominated by algal assemblage with hard coral comprising appr. 10% of the total surface. Overall, the results showed that sloping seawalls were significantly better at supporting coral communities, likely due to less intensive habitat compression and buffered wave action on them, especially at 0 m chart datum. The need to understand how surface topography affects benthic and coral communities in light of growing coastal urbanisation is also highlighted. This study emphasises how sloping seawalls can support greater marine biodiversity than vertical seawalls. [ABSTRACT FROM AUTHOR]

Intertidal habitats provide numerous ecosystem services, including the sequestration and storage of carbon, a topic of great recent interest owing to land-cover transitions and climate change. Mangrove forests and seagrass meadows form a continuum of intertidal habitats, alongside unvegetated mudflats and sandbars, however, studies that consider carbon stocks across these spatially-linked, threatened ecosystems are limited world-wide. This paper presents the results of a field-based carbon stock assessment of aboveground, belowground and sediment organic carbon stock to a depth of 1 m at Chek Jawa, Singapore. It is the first study of ecosystem carbon stocks of both vegetated and unvegetated intertidal habitats in the tropics. Ecosystem carbon stocks were 497 Mg C ha-1 in the mangrove forest and 138 Mg C ha-1 in the seagrass meadow. Sediment organic carbon stock dominated the total storage in both habitats, constituting 62% and >99% in the mangrove forest and seagrass meadow, respectively. In the adjacent mudflat and sandbars, which had no vegetative components, sediment organic carbon stock ranged from 124-143 Mg C ha-1, suggesting that unvegetated habitats have a carbon storage role on the same order of importance as seagrass meadows. This study reinforces the importance of sediment in carbon storage within the intertidal ecosystem, and demonstrates the need to consider unvegetated habitats in intertidal 'blue carbon' stock assessments. Copyright © 2015 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Octocorallia (Cnidaria: Anthozoa) from Singapore were collected and identifi ed in a survey conducted in 1999. Colonies collected previously, between 1993 and 1997, were also studied. The entire collection of ∼170 specimens yielded 25 species of the families Helioporidae, Alcyoniidae, Paraclcyoniidae, Xeniidae and Briareidae. Their distribution is limited to six m depth, due to high sediment levels and limited light penetration. The collection also yielded Cladiella hartogi, a new species (family Alcyonacea), which is described. All the other species are new zoogeographical records for Singapore. A comparison of species composition of octocorals collected in Singapore between 1993 and 1977 and those collected in 1999 revealed that out of the total number of species, 12 were found in both periods, whereas seven species, which had been collected during the earlier years, were no longer recorded in 1999. Notably, however, six species that are rare on Singapore reefs were recorded only in the 1999 survey and not in the earlier ones. It is not yet clear whether these differences in species composition indeed imply changes over time in the octocoral fauna, or may refl ect a sampling bias. The inclusion of octocorals in Singapore reef-monitoring programs will undoubtedly shed light on possible temporal changes in their species composition. The fi ndings do indicate, however, that the fl eshy octocoral fauna of Singapore is rather impoverished compared to other reefs in the region. [ABSTRACT FROM AUTHOR]

The giant clam, Tridacna crocea, is a sessile bivalve that bores into rocks and dead corals found on shallow Indo-Pacific coral reefs. Clams are a valuable prey item and T. crocea have developed at least two effective strategies to avoid predation: borrowing, and simultaneous rapid mantle withdrawal and valve contraction. Tridacna crocea obtain their food via photosynthetic products of symbiotic zooxanthellae and from filter-feeding. When they retract their mantles in response to predators, both photosynthesis and feeding are disrupted. Visible polymorphism and crypsis should reduce the frequency of attack and corresponding mantle retraction. In order to determine whether T. crocea is polymorphic and/or cryptic, samples ( n = 573) from Tioman Island, Malaysia, were surveyed and photographed. Classification of images into categories of size and mantle colour/pattern demonstrates that T. crocea is colour/pattern polymorphic and morph frequency is size-dependent. Eight morphs were identified, but there also existed considerable intra-morph variation. Morphs with brown and/or and green pigments dominated the larger clam size category (>8 cm). Furthermore, red/blue/green (RGB) values extracted from a subset ( n = 93) of digital images of T. crocea showed significant positive correlations between mantle and substrate colours (blue, r = 0.641; green, r = 0.540; red, r = 0.528), indicating background matching (crypsis). [ABSTRACT FROM AUTHOR]

The quantification of small-scale coral morphology using tissue-free skeletons often requires colonies, or colony sections, to be removed from the reef. This undesirable destruction can be reduced by using a with-tissue technique based on photographic images of living corals. The results of this study indicate that with-tissue multivariate morphometric data contain similar information to skeleton-derived data and can help identify phenotypic plasticity in the massive coral Favia speciosa. With-tissue data can also be used to discern changes with time in individual polyps exposed to new environments. [ABSTRACT FROM AUTHOR]

This note describes a portable, low-cost, pump-based, multi-purpose, surface–subsurface, phytoplankton and zooplankton sampler. It is self-powered by a small 12 V DC battery, and is portable and ideal for use from a small boat in a river, estuary, or sea. The sampler is equipped with a very sensitive microprocessor-controlled flow sensor for precise determination of the volume of water processed by the sampler. A study was carried out to evaluate the performance of this sampler in comparison to the conventional towed plankton net. The results of this study suggest that this pump-based sampler is as efficient in collecting plankton as using conventional plankton nets, with little damage to the organisms. [ABSTRACT FROM PUBLISHER]

The article presents the geographic information related to location of Anemonefish Amphiprion frenatus inhabiting another species of host sea anemone, Heteractis magnifica in Singapore. It highlights surveys conducted to document anemonefishes and their host sea anemones on July 25 and 26, 2018 on reefs fringing two offshore islands.

The article focuses on the Drupella rugosa on scleractinian coral Pocillopora damicornis associated with the outbreaks of the gastropods in some Indo-Pacific reefs. It examines the fragmentation of Pocillopora damicornis which were exposed in aquarium tanks with flow-through filtered seawater. It also stresses the translucent capsules deposited in clusters on the bare coral skeletons for the Drupella rugosa.

The article focuses on the conservation of coral reefs beside a marine landfill in Singapore. It is stated that part of Singapore's sea to the east of the island of Palau Semakau was assigned for landfill use after sites on the main island were not available. The development obliterated the coral reef on the east of the island but steps were made to protect the remaining western fringing reef. Silt screens were positioned to prevent sediment damage throughout the construction of the perimeter bund. The extensive reef flat supports an average live coral cover of 30 percent and 24 coral genera, as well as a good diversity of other reef invertebrates with large beds of seagrass.

The rates of oxygen production and respiration of the colonial zoanthid of the genus Palythoa were measured in situ at a depth of 3.4 m (reef-edge) using an automated respirometer. The respirometer recordedchanges in oxygen concentration of four samples of Palythoa enclosedin separate perspex chambers concurrently with light intensity (irradiance) readings every 20 seconds for 24 hours. Photosynthetic parameters (Pm(gross), Rd and Ik) were estimated from photosynthesis--irradiance (PI) curves generated for each of the four samples. Average instantaneous maximum gross photosynthetic (Pm(gross)) and respiration (Rd) rates obtained for Palythoa were 12.50 mu mol O2 cm- 2 h-1 and 4.24 mu mol O2 cm-2 h-1, giving a Pm(gross)/(-Rd) ratio of 2.92. The net 24 hour production (Pn24) at 3.4 m, estimated by integrating the photokinetic parameters over 7 days of light data, was negative, resulting in a daily gross photosynthesis to respiration [Pg24/(-Rd24)] ratio of 0.77, while estimated 24 hour productivity at 1.4 m gave a ratio of 1.13. This suggests that Palythoa would be able to sustain positive production at 1.4 m but not at 3.4 m. [ABSTRACT FROM AUTHOR]

Spatial distribution of the pomacentrids on Singapore reefs was assessed visually, while temporal change was studied within permanent quadrats established on a patch reef between 4 Jul and 30 Nov 1989. Partitioning of space, both horizontally and vertically on the reef was observed in 15 species The population of territorial damselfishes on the reef flat was less stable than on the reef slope over time, due tothe seasonal occurrence of dense stands of the brown microalgae, Sargassum. Space was found to be a limiting factor at the reef flat due to the high density of pomacentrids found there. Food resource was the limiting factor on the reef slope., where low light intensity due to sedimentation and lack of suitable substrate inhibited turf algal growth. Multi-specific recruitment of juveniles occurred in April and between mid-October and early November. [ABSTRACT FROM AUTHOR]

Marine environmental levels of the metals copper (Cu) zinc (Zn), lead (Pb) and cadmium (Cd) were measured from sediments collected around20 coastal locations around Singapore, over a 2-year period. Sediment size analysis was conducted on sediment samples, and Atomic Absorption Spectrophotometry was used in the analyses of sediment heavy metal concentrations. The levels of heavy metals in marine sediment was largely dependant on sediment particle size, as illustrated by the correlation of sediment size with Multidimensiona Scaling (MDS) configurations of sediment metal concentrations. In addition, the proximity to shipping activity, and the release of anti-fouling paint from boatsalso influence heavy metal concentrations in marine sediments of Singapore. [ABSTRACT FROM AUTHOR]

The growth of symbiotic algal cells (zooxanthellae) isolated from the coral, Montipora verrucosa under the influence of the heavy metals copper (Cu) and Zinc (Zn) was investigated. Zooxanthellae cells cultured in f/2 enriched seawater medium were subjected to a maximum Cu level of 42 mu g.l-1, Zn concentration of 509 mu g.l-1, and various combinations of the two metals, in ecotoxicological bioassays lasting up to 28 days. A Cu level of 40mu g.l-1 caused significantly depressed specific growth rates of cell cultures obtained using a standard growth model. Low concentrations of the metals Cu and Zn in combination elicited synergistic effects of sublethal toxicity. The use of cultured zooxanthellae cells in bioassays investigating sublethal effects of heavy metal stress has relevant applications in the field of pollution monitoring. [ABSTRACT FROM AUTHOR]

Artificial reefs are seen as effective tools to enhance the marine environment and increase productivity, particularly fish biomass and abundance. Many Southeast Asian countries have implemented artificial reef programmes. When effectively managed, artificial reefs enhance habitats and biological productivity. Management includes proper planning on the use and configuration of materials, site selection, and regulatory control of fisheries harvest. Without planning and long-termmanagement, artificial reefs fail and become nothing more than pollutants that contribute to the further degradation of the marine environment. [ABSTRACT FROM AUTHOR]

Zonation patterns of gorgonians from 15 sites on reefs south of the main island of Singapore reveal discontinuities in terms of both generic richness and total abundance. This establishes the crest, slope, and bottom as ecologically distinct environments of the reef, as interpreted by these gorgonian population parameters. Only members of thefamily Melithaeidae are able to colonise all three zones. Other genera are restricted to the slope and bottom; in particular, Aconthogorgia and Echinoinuricea are only found at the bottom zone. [ABSTRACT FROM AUTHOR]