Edgardo D. Gomez

Coral Reefs Under Rapid Climate Change and Ocean Acidification

Atmospheric carbon dioxide concentration is expected to exceed 500 parts per million and global temperatures to rise by at least 2°C by 2050 to 2100, values that significantly exceed those of at least the past 420,000 years during which most extant marine organisms evolved. Under conditions expected in the 21st century, global warming and ocean acidification will compromise carbonate accretion, with corals becoming increasingly rare on reef systems. The result will be less diverse reef communities and carbonate reef structures that fail to be maintained. Climate change also exacerbates local stresses from declining water quality and overexploitation of key species, driving reefs increasingly toward the tipping point for functional collapse. This review presents future scenarios for coral reefs that predict increasingly serious consequences for reef-associated fisheries, tourism, coastal protection, and people. As the International Year of the Reef 2008 begins, scaled-up management intervention and decisive action on global emissions are required if the loss of coral-dominated ecosystems is to be avoided.

A review of the status of Philippine reefs

Abstract Since 1979, the status of Philippine reefs has been periodically updated. While conditions of the reefs during the early surveys were assessed in terms of live coral cover per se, the ‘coral mortality index’ was applied to the sets of data collected during the past 7 yr which may be a better gauge in determining the health of the reefs. Generally, most reefs surveyed are in fair condition. Major destructive factors described are sedimentation and siltation from coastal development and activities inland, illegal and destructive methods of fishing, and overfishing. If the reefs are to continue to provide for the present and future users, the ecological processes that render them productive must be maintained through integrated approaches of coastal area management.

Evidence for changing symbiotic algae in juvenile tridacnids

This study investigated the effects of different clonal strains of Symbiodinium sp. (zooxanthellae) on clam growth and survival, while monitoring the persistence of the induced symbioses in outdoor tanks and in the field using allozyme and random amplified polymorphic DNA (RAPD) analyses. Aposymbiotic clam larvae that were inoculated with homologous zooxanthellae (cultured or freshly isolated from the same host species) or heterologous zooxanthellae (cultured from different host species) had significantly-different survival rates at harvest (3 months post-spawning) with small growth differences. The improved survival rates in juvenile Hippopus hippopus (heterologous infection) and Tridacna gigas (homologous infection) were maintained through 3 months onshore and 3 months offshore. However, isozyme and RAPD analyses of re-isolated zooxanthellae after 3, 6, and 9 months revealed a high genetic diversity of symbionts (ca. 99% variation in 200 re-isolates) from individual hosts, within and between treatments. Furthermore, the genetic patterns of the re-isolated algae following clonal culture were different from those of the introduced clones, which, in contrast, retained their unique genetic patterns over many culture generations in the laboratory. These results demonstrate that the subsequently-established symbiont populations in juvenile clams were not clonal. The allozyme and RAPD techniques detected individual genetic differences in clam symbionts, but not differences between algal taxa. The presence of significant survival trends suggests possible differences between subsequently-established dominant symbiont taxa, which were uncultureable or undetectable using these genetic markers. The implications of this symbiont diversity in giant clams are discussed.

Multi-species spawning of corals in north-western Philippines

The Philippines has more than 30,000 km of reef area and hosts some of the world’s most diverse and endangered coral communities, however there is little information on patterns of coral reproduction (Bermas et al. 1992) and to date there are no published accounts of direct spawning observations. Sampling to determine the reproductive state of Acropora species and in situ observations of coral spawning was conducted in 2006 and 2007 at sites close to the Bolinao Marine Laboratory (BML) in northwestern Luzon, (16 22¢N 119 54¢E). Prior to the full moon in March 2006, 22 sampled Acropora species (67% of colonies, n = 208) contained white or pigmented oocytes large enough to be visible in branches that were fractured artificially underwater (for methods see Baird et al. 2002) suggesting a seasonal peak in reproduction from March to May. Night dives were carried out during the week following the full moons of 15 March and 14 April 2006; and 2 April, 2 May and 1 June 2007. Multi-species coral spawning was observed during all of the months of observation except in April 2007. Across all months of observation, a total of at least 36 scleractinian species belonging to 14 genera and 7 families (Acroporidae, Mussidae, Agariciidae, Faviidae, Oculinidae, Merulinidae and Poritidae) broadcast spawned (Fig. 1), with a maximum of 13 species observed on the fifth night after full moon in May 2007. Further studies are required to establish the extent of spawning at other times of the year and the reproductive patterns of corals elsewhere in the Philippines.

Reef management in developing countries: a case study in the Philippines

Abstract. In general the most attractive and economically valuable reefs in the world are found in developing countries. Because of these attributes, they have also become the most endangered. Due to anthropogenic threats to their productivity, there is a growing need for management. Programs for their conservation and rehabilitation are being mounted at local, regional, and international levels. Local efforts are widely distributed, showing signs of both failure and success. The situation in developing countries differs from that which prevails in developed countries for various reasons, including level of awareness, infrastructure, and law enforcement. A case history of saving a coral reef ecosystem is described in this study. It involves a recent plan to build a cement factory in the Philippines at Bolinao.

Successful Transplantation of a Fragmenting Coral, Montipora digitata, for Reef Rehabilitation

The scleractinian coral Montipora digitata (Acroporidae) is a common reef flat species that thrives under high levels of light and water turbulence, and propagates successfully by natural fragmentation. It was used for transplantation experiments in an attempt to restore a degraded lagoon environment in the northwestern Philippines. Branches about 5 cm high from a natural population in the lagoon were transplanted to dead coral outcrops or knolls in two locations (Binlab and Malilnep-Ac) with different environmental characteristics. Growth and survival were significantly better at Malilnep Ac, which resembled the natural habitat of the species more closely. Environmental conditions at this site also favored the establishment of a greater diversity of species around the coral transplants. There was no difference in performance between transplants on vertical and horizontal surfaces, and the transplants showed limited differences due to density within the experimental range. Significant survival of detached, transplanted colonies or fragments thereof around the bases of the experimental bommies at the more successful site was an additional positive outcome. Water motion showed significant effects on survival and growth, possibly enhancing the suitability of the more successful site for transplantation. These results demonstrate the potential of coral transplantation to initiate the establishment of natural communities in degraded reef areas, a concern for coastal managers in developing countries.

The spaghetti sponge Callyspongia samarensis (Wilson, 1925) provides temporary habitat for reef fish recruits

The lagoon areas in the Bolinao reef complex (northwestern Luzon, the Philippines) used to harbor numerous live coral outcrops. However, coral cover here, as well as in nearby reef zones, has diminished since the 1998 bleaching event (Arceo et al. 2001), and the degradation is exacerbated during decades of blast fishing. Coral recruitment and reef recovery have been very slow recently and continue to be hampered by the apparent lack of larvae and suitable habitats for them to settle, particularly for corals and juvenile fish. Live coral cover has been reduced to about 1 % inside the lagoon, where dead corals prevail (48 %) and sponges are common (24 %). The latter are dominated by the spaghetti sponge Callyspongia samarensis (Wilson, 1925) , whose loose ly ar ranged branches may successfully compete for space with corals by means of overshadowing (Fig. 1a). More importantly, it might also potentially hinder the settlement and survival of coral recruits as some sponges have been observed to be aggressive towards adult corals (Chadwick and Morrow 2011). Recent field observations, however, have suggested that C. samarensis can serve as habitat and nursery site for some reef fishes (Fig. 1b). It appears to be a weedy species that can occur after disturbance events (Wulff 2012), and by doing so, it provides a three-dimensional structure that is otherwise lacking, retaining some ecological functions of the original environment (compare Schonberg et al. 2015). The tangles of the spaghetti sponge may provide shelter that was previously offered by branching corals, constituting protection for small fish. It is assumed that juvenile fish residing in the sponge thickets have the opportunity to grow in size until they are ready to colonize other reef habitats. Since the sponge is ephemeral, with abundances fluctuating seasonally, this protection is not permanent. Thus, the sponges, though putative space competitors for hard corals, offer an important benefit to the reef fish community. The present report demonstrates that the Communicated by B. W. Hoeksema

The significance of the giant clam Tridacna squamosa at Tubuai, Austral Islands, French Polynesia

Gilbert et al. (2007) report Tridacna squamosa at »20 m depth oV Tubuai (23°20 S, 145°20 W) an Indo-west PaciWc species previously unknown in French Polynesia. They go on to propose that the discovery corroborates a peripheral dispersal hypothesis of Randall (1995): e.g., some species colonized remote islands of the eastern Polynesia from the west via high latitude islands such as the Australs before they dispersed to the more central, tropical reaches. T. squamosa, however, had already been recorded as a questionable fossil from the Tuamotus, and as extant in easternmost Polynesia (Pitcairn 25°04 S 130°65 W; Paulay 1989), and Newman and Gomez 2003 had proposed a reliction hypothesis to account for the apparent longitudinal disjunction between the Marshall and/or Cook Islands to Pitcairn (»160°E to 130°W). Furthermore, they noted that similar disjunctions can be found in Veron (2000) for as many as 31 species of otherwise widely distributed zooxanthellate corals. The Tridacninae completely died out in the tropical Atlantic, evidently due to restriction of the tropics in general. Therefore, reliction to the Indo-west PaciWc was at the subfamilial level. Like Tridacna maxima, T. squamosa ranges throughout the tropics from East Africa to the Marshall and Cook Islands, but it has a greater depth range (0–25.5 m; Juinio et al 1989). Of the living species, only the SW PaciWc relic, Tridacna mbalavuana, is found at greater depths. Where found in eastern Polynesia, T. squamosa is also restricted to deep water, and this is interpreted as a sign of reliction rather than some ecological complication such as lack of appropriate habitat or dispersal limitations. Thus, a reliction rather than a peripheral dispersal hypothesis seems to apply. But whatever the case may be, why T. squamosa is so restricted would remain puzzling even if it turned out simply to be very patchy rather than completely absent from the central reaches of western French Polynesia.

Rehabilitation of Biological Resources: Coral Reefs and Giant Clam Populations Need to Be Enhanced for a Sustainable Marginal Sea in the Western Pacific

This short article arose from a presentation at the workshop on “Implementing the DOC (Declaration of Conduct) and Cooperation Mechanisms in the South China Sea” held on 14–15 August 2014 in Haikou, Hainan, China. While the emphasis is on the environmental and biological concerns besetting the region, some aspects of legal considerations will be dealt with. For the general reader who is not well informed about the issues in and around the South China Sea, a recent readable book by Robert D. Kaplan titled “Asia’s Cauldron” presents one writer’s roundup of the issues and problems in broad strokes. A second recent book is Bill Hayton’s “The South China Sea—The Struggle for Power in Asia,” which provides a readable historical account of the developments that have led to the present situation. The interested reader can then go into more detailed research on the various facets of the history, present challenges, and possible future scenarios for this exciting marginal sea where much commerce takes place or transits, as described briefly in Kaplan. Both books have extensive notes and bibliographies for further reading. From the scientific and conservation perspectives, sporadic articles have been written on diverse issues from different authors. Closer to the author’s own experience, two references are Gomez and McManus, the latter