Francesca Benzoni

The Gulf: A young sea in decline

This review examines the substantial changes that have taken place in marine habitats and resources of the Gulf over the past decade. The habitats are especially interesting because of the naturally high levels of temperature and salinity stress they experience, which is important in a changing world climate. However, the extent of all natural habitats is changing and their condition deteriorating because of the rapid development of the region and, in some cases from severe, episodic warming episodes. Major impacts come from numerous industrial, infrastructure-based, and residential and tourism development activities, which together combine, synergistically in some cases, to cause the observed deterioration in most benthic habitats. Substantial sea bottom dredging for material and its deposition in shallow water to extend land or to form a basis for huge developments, directly removes large areas of shallow, productive habitat, though in some cases the most important effect is the accompanying sedimentation or changes to water flows and conditions. The large scale of the activities compared to the relatively shallow and small size of the water body is a particularly important issue. Important from the perspective of controlling damaging effects is the limited cross-border collaboration and even intra-country collaboration among government agencies and large projects. Along with the accumulative nature of impacts that occur, even where each project receives environmental assessment or attention, each is treated more or less alone, rarely in combination. However, their combination in such a small, biologically interacting sea exacerbates the overall deterioration. Very few similar areas exist which face such a high concentration of disturbance, and the prognosis for the Gulf continuing to provide abundant natural resources is poor.

Use of Habitats as Surrogates of Biodiversity for Efficient Coral Reef Conservation Planning in Pacific Ocean Islands

Marine protected areas (MPAs) have been highlighted as a means toward effective conservation of coral reefs. New strategies are required to more effectively select MPA locations and increase the pace of their implementation. Many criteria exist to design MPA networks, but generally, it is recommended that networks conserve a diversity of species selected for, among other attributes, their representativeness, rarity, or endemicity. Because knowledge of species spatial distribution remains scarce, efficient surrogates are urgently needed. We used five different levels of habitat maps and six spatial scales of analysis to identify under which circumstances habitat data used to design MPA networks for Wallis Island provided better representation of species than random choice alone. Protected-area site selections were derived from a rarity-complementarity algorithm. Habitat surrogacy was tested for commercial fish species, all fish species, commercially harvested invertebrates, corals, and algae species. Efficiency of habitat surrogacy varied by species group, type of habitat map, and spatial scale of analysis. Maps with the highest habitat thematic complexity provided better surrogates than simpler maps and were more robust to changes in spatial scales. Surrogates were most efficient for commercial fishes, corals, and algae but not for commercial invertebrates. Conversely, other measurements of species-habitat associations, such as richness congruence and composition similarities provided weak results. We provide, in part, a habitat-mapping methodology for designation of MPAs for Pacific Ocean islands that are characterized by habitat zonations similar to Wallis. Given the increasing availability and affordability of space-borne imagery to map habitats, our approach could appreciably facilitate and improve current approaches to coral reef conservation and enhance MPA implementation.

DNA barcoding reveals the coral “laboratory-rat”, Stylophora pistillata encompasses multiple identities

Stylophora pistillata is a widely used coral “lab-rat” species with highly variable morphology and a broad biogeographic range (Red Sea to western central Pacific). Here we show, by analysing Cytochorme Oxidase I sequences, from 241 samples across this range, that this taxon in fact comprises four deeply divergent clades corresponding to the Pacific-Western Australia, Chagos-Madagascar-South Africa, Gulf of Aden-Zanzibar-Madagascar, and Red Sea-Persian/Arabian Gulf-Kenya. On the basis of the fossil record of Stylophora, these four clades diverged from one another 51.5-29.6u2005Mya, i.e., long before the closure of the Tethyan connection between the tropical Indo-West Pacific and Atlantic in the early Miocene (16–24u2005Mya) and should be recognised as four distinct species. These findings have implications for comparative ecological and/or physiological studies carried out using Stylophora pistillata as a model species, and highlight the fact that phenotypic plasticity, thought to be common in scleractinian corals, can mask significant genetic variation.

Coral communities of the northwestern Gulf of Aden (Yemen): variation in framework building related to environmental factors and biotic conditions

Coral communities were investigated in the northwestern Gulf of Aden, Yemen, for their composition, structure, and bioconstruction potential. Although no true reef was encountered, high cover coral carpets were found where hard substrate was available. Seven different types of coral communities were differentiated, and both non-framework and framework coral communities were found. Monotypy or oligotypy seem to be consistent characteristics of framework-building coral communities in the study area. Apart from substrate availability, proximity to the upwelling area and exposure were found to be the most important environmental factors influencing coral communities’ structure, composition, and bioconstruction potential.

Genetic and morphometric evidence for unresolved species boundaries in the coral genus Psammocora (Cnidaria; Scleractinia)

A comparative morphological and molecular characterization of species boundaries between four species of the Scleractinian genus Psammocora, namely P. digitata, P. haimeana, P. profundacella and P. contigua was conducted. The definition of species boundaries in this genus has been the subject of few studies, in spite of the presence of ambiguous taxonomic distinction, and a revision of the genus has never been undertaken. The multivariate analyses of both descriptive and morphometric characters confirmed the distinction of P. digitata and P. contigua, conversely P. haimeana, P. profundacella and their intermediate morph differentiated on the basis of descriptive morphologic characters only. Morphometric characters alone allowed a less defined distinction between morphs, and morphological boundaries essentially intergraded in a gradient driven by enclosed corallite series characters.The phylogenetic analysis of a portion of the rDNA confirmed the morphological inferences, as P. digitata appears to be a distinct evolutionary lineage. Conversely, the other four morphs, P. contigua, P. haimeana, P. profundacella and their intermediate constitute a polytomic gene pool significantly distinct from P. digitata. Yet, P. contigua is significantly distinct from the other three morphs. Both morphological and molecular approaches suggested that P. haimeana, P. profundacella and their intermediate cannot be considered clearly distinct entities. Hybridization with other species of this genus not included in this study, or recent origin may have contributed to the polyphyly and lack of phylogenetic resolution of P. haimeana, P. profundacella and their intermediate morph. They appear to constitute a single gene pool showing morphological characters encompassing a gradient from the P. haimeana to the P. profundacella morphs. Such morphological variability possibly depends on environmental factors such as light conditions.

Coral disease mimic: sponge attacks Porites lutea in Yemen

Coral communities in South Yemen, are dominated by large Porites colonies accounting for up to 47% of the total benthic cover and forming a high three-dimensional framework. A distinct orange-reddish band spreading over approximately 50% of the Porites lutea colonies was recently observed (Fig. 1a). As the band progressed over the coral it faded behind leaving the dead coral skeleton for other organisms to colonise (Fig. 1a). Although spreading like a coral disease, the band was actually an infestation of a sponge belonging to the genus Clathria (Microciona) forming encrustations less than 1 mm thick. The subsurface canals of the aquiferous system meandering from oscules are visible in Fig. 1b. Clathria (Microciona) insinuates within the first 1–2 mm of the coral skeleton (Fig. 1c) filling corallites (Fig. 1d) and leaving spicules (Fig. 1e). No signs of bioerosion were visible. Toxic substances production could explain the successful overgrowth of the coral. Coral tissue destruction was rapid; preliminary results indicate it grows at an average rate of 1 cm month. Up to now Terpios hoshinota has been reported to threaten Pacific corals especially in polluted and stressed areas (Plucer-Rosario 1987; Rutzler and Muzik 1993) and Mycale grandis rapidly overgrows corals in Hawai’i (Coles and Bolick 2007). Clathria (Microciona) sp., however, differs from these sponges in presenting an unusual growth strategy leaving the dead coral skeleton behind and being strongly species-specific for Porites lutea.

End to End Digitisation and Analysis of Three-Dimensional Coral Models, from Communities to Corallites

Coral reefs hosts nearly 25% of all marine species and provide food sources for half a billion people worldwide while only a very small percentage have been surveyed. Advances in technology and processing along with affordable underwater cameras and Internet availability gives us the possibility to provide tools and softwares to survey entire coral reefs. Holistic ecological analyses of corals require not only the community view (10s to 100s of meters), but also the single colony analysis as well as corallite identification. As corals are three-dimensional, classical approaches to determine percent cover and structural complexity across spatial scales are inefficient, time-consuming and limited to experts. Here we propose an end-to-end approach to estimate these parameters using low-cost equipment (GoPro, Canon) and freeware (123D Catch, Meshmixer and Netfabb), allowing every community to participate in surveys and monitoring of their coral ecosystem. We demonstrate our approach on 9 species of underwater colonies in ranging size and morphology. 3D models of underwater colonies, fresh samples and bleached skeletons with high quality texture mapping and detailed topographic morphology were produced, and Surface Area and Volume measurements (parameters widely used for ecological and coral health studies) were calculated and analysed. Moreover, we integrated collected sample models with micro-photogrammetry models of individual corallites to aid identification and colony and polyp scale analysis.

Stylocoeniella nikei n. sp., a new zooxanthellate coral from the Pacific (Cnidaria, Anthozoa, Scleractinia)

Abstract Stylocoeniella nikei, a new zooxanthellate astrocoeniid scleractinia is described, and affinities with the two other living species of Stylocoeniella are discussed. It lives on sedimentary substrates, in sheltered environments.