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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 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 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]

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]