Effects of climate change on coral grouper (<Emphasis Type="Italic">Plectropomus</Emphasis> spp.) and possible adaptation options

Global climate change is increasingly considered one of the major threats to tropical coastal fisheries, potentially undermining important revenue and food security provided by coral reef ecosystems. While there has been significant and increasing work on understanding specific effects of climate change on coral reef fishes, few studies have considered large-bodied fisheries target species, limiting understanding of the effects of climate change on tropical fisheries. This review focuses on coral grouper (Plectropomus spp., and mainly Plectropomus leopardus), which are heavily fished throughout the Indian and Pacific oceans, and represent an exemplar group to assess potential effects of climate change on coral reef fisheries. In experimental studies, P. leopardus appear to be extremely sensitive to increasing ocean temperature, exhibiting declines in survivorship, aerobic scope and activity with relatively moderate increases in temperature. As such, ongoing ocean warming may jeopardize the catchability of coral grouper and sustainability of reef-based fisheries, especially at low latitudes. Notably, a significant portion of wild stocks of P. leopardus are already exposed to temperatures (≥30 °C) that have been shown to compromise individual performance and body condition. While there are considerable knowledge gaps in predicting effects of global climate change on coral grouper, such as their capacity to avoid, acclimate or adapt to changes in local environmental conditions, current information suggests that there is cause for concern. As such, we take the formative steps to outline both ecological and socioeconomic adaptations that could reduce vulnerability of coral reef fisheries to climate impacts on stocks of coral grouper, using a linked socio-economic framework.     

Host-dependent differences in measures of condition associated with <Emphasis Type="Italic">Anilocra</Emphasis> spp. parasitism in two coral reef fishes

Parasites account for over half of the biodiversity on coral reefs, yet their ecological impacts are poorly understood. Cymothoid isopods of the genus Anilocra are large, conspicuous ectoparasites of coral reef fishes. French grunt (Haemulon flavolineatum) and brown chromis (Chromis multilineata) are commonly infected by Anilocra spp. in the Caribbean. These fishes play a significant role in trophic connectivity through their foraging and activity patterns, and Anilocra spp. infection has been reported to influence the trophic interactions of some fishes. Yet, how these changes manifest physiologically has not been quantified. Thus to determine the energetic effects of Anilocra spp. on French grunt and brown chromis, the relationships between Anilocra spp. infection and condition factor, percent moisture in the muscle tissue, total muscle tissue calories, and gut content volume were examined. The results of these analyses revealed that A. haemuli-infected French grunt had greater percent moisture in the muscle tissue but similar condition scores, calorie values, and gut content volumes compared to uninfected conspecifics. By comparison, Anilocra chromis-infected brown chromis had reduced condition factor, but similar percent moisture in the muscle tissue and total muscle tissue calories, as compared to uninfected conspecifics. This study provides evidence that infection by parasites of the same genus and within the same localities can have differential effects on fish host species, such that generalizations about the effects of parasitism across and within genera should be made cautiously.     

Interseasonal and interspecies diversities of <Emphasis Type="Italic">Symbiodinium</Emphasis> density and effective photochemical efficiency in five dominant reef coral species from Luhuitou fringing reef,northern South China Sea

Although it is well established that different coral species have different susceptibilities to thermal stress, the reasons behind this variation are still unclear. In this study, 384 samples across five dominant coral species were collected seasonally between September 2013 and August 2014 at Luhuitou fringing reef in Sanya, Hainan Island, northern South China Sea, and their algal symbiont density and effective photochemical efficiency (Φ _PSII) were measured. The results indicated that both the Symbiodinium density and Φ _PSII of corals were subject to significant interspecies and seasonal variations. Stress-tolerant coral species, including massive Porites lutea and plating Pavona decussata, had higher symbiont densities but lower Φ _PSII compared to the vulnerable branching species of Acropora over the course of all four seasons. Seasonally, coral symbiont densities were the lowest during winter, while during the same period, Φ _PSII of corals was at the highest point. Further analysis suggested that dissolved inorganic nutrients and upwelling in the reef area were probably responsible for the observed seasonal variations in symbiont density. The fact that Porites lutea has the lowest Φ _PSII during all four seasons is likely related to their symbionts’ lower capacity to provide required photosynthates for calcification. These results suggest that a coral’s thermal tolerance is primarily and positively dependent on its symbiont density and is less related to its effective photochemical efficiency.     

Microhabitat characteristics of <Emphasis Type="Italic">Stegastes planifrons</Emphasis> and <Emphasis Type="Italic">S. adustus</Emphasis> territories

Stegastes adustus and Stegastes planifrons are two species of damselfishes commonly found in the Caribbean. These territorial fishes have been widely studied due to their major ecological role on coral reef in controlling the growth of macroalgae that compete with corals for space and, inversely, on their deleterious role in destroying coral tissues to impulse the development of algae. However, few studies were conducted on the biotic and abiotic components of their territories. In the present study, territory size and surfaces of benthic components (macroalgae, algal turf, massive corals, branching corals, Milleporidae, sponges, sand and rubbles) were estimated for the two species at two contrasted sites. At Ilet Pigeon site (IP), the two damselfishes were found at different depth and exhibited different territory sizes. S. adustus defended a larger territory characterized by massive corals, sand and Milleporidae, while S. planifrons territories were smaller, deeper and characterized by branching corals, sponges and rubble. At Passe-à-Colas site (PC), the two fish species coexisted in the same depth range and defended territories of similar size. Their territories presented higher proportions of macroalgae, but smaller surfaces of Milleporidae than at IP. At PC, the main difference between the two species was a higher surface of massive corals inside S. planifrons territories than S. adustus territories. Differences in microhabitat characteristics between the two Stegastes seemed mostly site related. This resulted from the high plasticity of two species, allowing them to persist on Caribbean coral reefs after the decline of most branching acroporids, their former favorite habitats.     

Variability in chemical defense across a shallow to mesophotic depth gradient in the Caribbean sponge <Emphasis Type="Italic">Plakortis angulospiculatus</Emphasis>

The transition between shallow and mesophotic coral reef communities in the tropics is characterized by a significant gradient in abiotic and biotic conditions that could result in potential trade-offs in energy allocation. The mesophotic reefs in the Bahamas and the Cayman Islands have a rich sponge fauna with significantly greater percent cover of sponges than in their respective shallow reef communities, but relatively low numbers of spongivores. Plakortis angulospiculatus, a common sponge species that spans the depth gradient from shallow to mesophotic reefs in the Caribbean, regenerates faster following predation and invests more energy in protein synthesis at mesophotic depths compared to shallow reef conspecifics. However, since P. angulospiculatus from mesophotic reefs typically contain lower concentrations of chemical feeding deterrents, they are not able to defend new tissue from predation as efficiently as conspecifics from shallow reefs. Nonetheless, following exposure to predators on shallow reefs, transplanted P. angulospiculatus from mesophotic depths developed chemical deterrence to predatory fishes. A survey of bioactive extracts indicated that a specific defensive metabolite, plakortide F, varied in concentration with depth, producing altered deterrence between shallow and mesophotic reef P. angulospiculatus. Different selective pressures in shallow and mesophotic habitats have resulted in phenotypic plasticity within this sponge species that is manifested in variable chemical defense and tissue regeneration at wound sites.     

Climate-driven coral reorganisation influences aggressive behaviour in juvenile coral-reef fishes

Globally, habitat degradation is altering the abundance and diversity of species in a variety of ecosystems. This study aimed to determine how habitat degradation, in terms of changing coral composition under climate change, affected abundance, species richness and aggressive behaviour of juveniles of three damselfishes (Pomacentrus moluccensis, P. amboinensis and Dischistodus perspicillatus, in order of decreasing reliance on coral). Patch reefs were constructed to simulate two types of reefs: present-day reefs that are vulnerable to climate-induced coral bleaching, and reefs with more bleaching-robust coral taxa, thereby simulating the likely future of coral reefs under a warming climate. Fish communities were allowed to establish naturally on the reefs during the summer recruitment period. Climate-robust reefs had lower total species richness of coral-reef fishes than climate-vulnerable reefs, but total fish abundance was not significantly different between reef types (pooled across all species and life-history stages). The nature of aggressive interactions, measured as the number of aggressive chases, varied according to coral composition; on climate-robust reefs, juveniles used the substratum less often to avoid aggression from competitors, and interspecific aggression became relatively more frequent than intraspecific aggression for juveniles of the coral-obligate P. moluccensis. This study highlights the importance of coral composition as a determinant of behaviour and diversity of coral-reef fishes.     

Habitat preferences of the <Emphasis Type="Italic">Pteroclava krempfi</Emphasis>-alcyonaceans symbiosis: inner vs outer coral reefs

Herein, we provide observation on the ecological relationships between the hydrozoan species Pteroclava krempfi and three alcyonacean genera: Lobophytum, Sarcophyton and Sinularia from protected and exposed reef habitats in the Maldives. The associations were found to be widespread in the investigated area with both an overall and taxon-specific symbiosis prevalence higher in the exposed reef sites. Pteroclava krempfi most frequently occurred with Lobophytum, followed by Sinularia and Sarcophyton. The prevalence of P. krempfi with soft corals was also positively correlated to percent host cover, which was higher in the outer reef sites, suggesting a host-reliant relationship for the hydrozoan. However, the nature of these relationships, as as well as the factors that drive their establishment, requires further investigation. The widespread degradation of coral reef ecosystems endangers the existence of many poorly understood, but intimate relationships that often go unrecognized.     

Genomic clues to the parental origin of the wild flowering cherry <Emphasis Type="Italic">Prunus yedoensis</Emphasis> var. <Emphasis Type="Italic">nudiflora</Emphasis> (Rosaceae)

Prunus yedoensis Matsumura is one of the popular ornamental flowering cherry trees native to northeastern Asia, and its wild populations have only been found on Jeju Island, Korea. Previous studies suggested that wild P. yedoensis (P. yedoensis var. nudiflora) is a hybrid species; however, there is no solid evidence on its exact parental origin and genomic organization. In this study, we developed a total of 38 nuclear gene-based DNA markers that can be universally amplifiable in the Prunus species using 586 Prunus Conserved Orthologous Gene Set (Prunus COS). Using the Prunus COS markers, we investigated the genetic structure of wild P. yedoensis populations and evaluated the putative parental species of wild P. yedoensis. Population structure and phylogenetic analysis of 73 wild P. yedoensis accessions and 54 accessions of other Prunus species revealed that the wild P. yedoensis on Jeju Island is a natural homoploid hybrid. Sequence-level comparison of Prunus COS markers between species suggested that wild P. yedoensis might originate from a cross between maternal P. pendula f. ascendens and paternal P. jamasakura. Moreover, approximately 81% of the wild P. yedoensis accessions examined were likely F1 hybrids, whereas the remaining 19% were backcross hybrids resulting from additional asymmetric introgression of parental genotypes. These findings suggest that complex hybridization of the Prunus species on Jeju Island can produce a range of variable hybrid offspring. Overall, this study makes a significant contribution to address issues of the origin, nomenclature, and genetic relationship of ornamental P. yedoensis.     

Influence of the coral reef assemblages on the spatial distribution of echinoderms in a gradient of human impacts along the tropical Mexican Pacific

Fourteen species of echinoderms and their relationships to the benthic structure of the coral reefs were assessed at 27 sites—with different levels of human disturbances—along the coast of the Mexican Central Pacific. Diadema mexicanum and Phataria unifascialis were the most abundant species. The spatial variation of the echinoderm assemblages showed that D. mexicanum, Eucidaris thouarsii, P. unifascialis, Centrostephanus coronatus, Toxopneustes roseus, Holothuria fuscocinerea, Cucumaria flamma, and Echinometra vanbrunti accounted for the dissimilarities among the sites. The spatial variation among the sites was mainly explained by the cover of the hard corals (Porites, Pocillopora, Pavona, Psammocora), different macroalgae species (turf, encrusting calcareous algae, articulated calcareous algae, fleshy macroalgae), sponges, bryozoans, rocky, coral rubble, sand, soft corals (hydrocorals and octocorals), Tubastrea coccinea coral, Balanus spp., and water depth. The coverage of Porites, Pavona, and Pocillopora corals, soft coral, rock, and Balanos shows a positive relationship with the sampling sites included within the natural protected area with low human disturbances. Contrary, fleshy macroalgae, sponges, and soft coral show a positive relationship with higher disturbance sites. The results presented here show the importance of protecting the structural heterogeneity of coral reef habitats because it is a significant factor for the distribution of echinoderm species and can contribute to the design of conservation programs for the coral reef ecosystem.     

<Emphasis Type="Italic">Megaviridae</Emphasis>-like particles associated with <Emphasis Type="Italic">Symbiodinium</Emphasis> spp. from the endemic coral <Emphasis Type="Italic">Mussismilia braziliensis</Emphasis>

Coral reefs are one of the most dynamic and productive marine ecosystems. The coral holobiont consists of the coral animal and a variety of associated microorganisms that include symbiotic dinoflagellates of the genus Symbiodinium, bacteria, archaea, fungi and viruses. The interactions among these components are crucial for coral health and, consequently, to the coral reef resilience to disturbance. Environmental stressors such as elevated temperature, high irradiance and ultraviolet (UV) radiation can lead to the breakdown of the coral-Symbiodinium symbiosis in a phenomenon known as “coral bleaching”. The present study provides evidence for virus-like particles (VLPs) induced in UV-irradiated Symbiodinium spp. cultures (clades A and C) that were isolated from the coral Mussismilia braziliensis, suggesting a latent viral infection in these strains. Scanning and transmission electron microscopy images of the UV stressed cultures revealed the presence of giant (ca. 450 nm) and small (ca. 40 nm) VLPs. Morphological features link the giant VLPs to the family Megaviridae. Symbiodinium spp. Megaviridae giant viruses and other associated viruses may represent dynamic forces driving and influencing health of the coral holobiont.     

Hyperstability masks declines in bumphead parrotfish (<Emphasis Type="Italic">Bolbometopon muricatum</Emphasis>) populations

Bolbometopon muricatum, the largest species of parrotfish, is a functionally important species that is characterised by the formation of aggregations for foraging, reproductive, and sleeping behaviours. Aggregations are restricted to shallow reef habitats, the locations of which are often known to local fishers. Bolbometopon muricatum fisheries are therefore vulnerable to overfishing and are likely to exhibit hyperstability, the maintenance of high catch per unit effort (CPUE) while population abundance declines. In this study, we provide a clear demonstration of hyperstable dynamics in a commercial B. muricatum fishery in Isabel Province, Solomon Islands. Initially, we used participatory mapping to demarcate the Kia fishing grounds into nine zones that had experienced different historic levels of fishing pressure. We then conducted comprehensive underwater visual census (UVC) and CPUE surveys across these zones over a 21-month period in 2012–2013. The individual sites for replicate UVC surveys were selected using a generalised random tessellation stratified variable probability design, while CPUE surveys involved trained provincial fisheries officers and local spearfishers. A comparison of fishery-independent abundance data and fishery-dependent CPUE data indicate extreme hyperstability, with CPUE maintained as B. muricatum abundance declines towards zero. Hyperstability may explain the sudden collapses of many B. muricatum spear fisheries across the Pacific and highlights the limitations of using data-poor fisheries assessment methods to evaluate the status of commercially valuable coral reef fishes that form predicable aggregations.     

DNA taxonomy in the timber genus <Emphasis Type="Italic">Milicia</Emphasis>: evidence of unidirectional introgression in the West African contact zone

DNA-based techniques are helpful in characterising hybridisation patterns in plant species. To be efficient in disentangling species boundaries and interspecific gene flow, it is recommended to combine various methodologies and types of markers. Here, we used different analytical tools (algorithms implemented in Structure, Tess, NewHybrids and HIest, and the haploweb approach) and three nuclear genetic markers (7 nuclear simple sequence repeat loci (SSRs), 62 single-nucleotide polymorphism loci (SNPs) and a single-copy gene region, At103) to revisit hybridisation patterns in the commercially important African tree genus Milicia. Samples were collected in the natural ranges of Milicia regia and Milicia excelsa in West Africa. Using real data sets, simulated purebreds and hybrid genotypes, we found that SNPs yielded results more consistent than SSRs; outputs from the Bayesian and maximum-likelihood analyses differed significantly using the SSRs, whereas they were perfectly congruent using SNPs. A proportion of 12.4% hybrids were detected amongst the SNP genotype samples. A haploweb analysis of At103 gene sequences confirmed the existence of interspecific hybrids. There was also a clear evidence of advanced generations of hybrids (backcrossed individuals) but only towards M. regia. Although more investigation is required for understanding the mechanisms responsible for this asymmetric introgression, we suggest that it may be due to the differences in flowering time between species and between sexes, combined with a maternal inheritance of flowering time.     

Predation on crown-of-thorns starfish larvae by damselfishes

Examining the functional response of predators can provide insight into the role of predation in structuring prey populations and ecological communities. This study explored feeding behaviour and functional responses of planktivorous damselfishes when offered captive reared larvae of crown-of-thorns starfish, Acanthaster sp., with the aim of determining whether these predators could ever play a role in moderating outbreaks of Acanthaster sp. We examined predatory behaviour of 11 species of planktivorous damselfish, testing: (1) the relationship between predator size and predation rate, both within and among fish species; (2) consumption rates on larvae of Acanthaster sp. versus larvae of a common, co-occurring coral reef asteroid Linckia laevigata; (3) maximal feeding rates upon both Acanthaster sp. and L. laevigata; and (4) functional responses of planktivorous fishes to increasing densities of Acanthaster sp. Consumption rates of crown-of-thorns larvae by damselfishes were independent of predator size; however, there was a significant negative relationship between predator size and consumption rate of L. laevigata, when pooling across all predatory species. Some damselfishes, including Acanthochromis polyacanthus and Amblyglyphidodon curacao, consumed larval Acanthaster sp. at a greater rate than for L. laevigata. Most predatory species (all except A. curacao and Pomacentrus amboinensis) exhibited a Type II functional response whereby the increasing feeding rate decelerated with increasing prey density. In addition to revealing that a wide range of planktivorous fishes can prey upon larvae of Acanthaster sp., these data suggest that planktivorous damselfishes may have the capacity to buffer against population fluctuations of Acanthaster sp. Importantly, predators with Type II functional responses often contribute to stability of prey populations, though planktivorous fishes may be swamped by an abnormally high influx of larvae, potentially contributing to the characteristic population fluctuations of Acanthaster sp.     

Two species of <Emphasis Type="Italic">Neometadena</Emphasis> Hafeezullah &amp; Siddiqi, 1970 (Digenea: Cryptogonimidae) from Moreton Bay,Australia, including the description of <Emphasis Type="Italic">Neometadena paucispina</Emphasis> n. sp. from Australian Lutjanidae

A survey of the trematode fauna of lutjanid fishes off the east coast of Queensland (QLD), Australia revealed the presence of two species of Neometadena Hafeezullah & Siddiqi, 1970 (Digenea: Cryptogonimidae). Neometadena paucispina n. sp. is described from the intestine and pyloric caeca of Lutjanus fulviflamma (Forsskål) and L. russellii (Bleeker) from Moreton Bay, in southeast QLD. Specimens of the type- and only other species, N. ovata (Yamaguti, 1952) Miller & Cribb, 2008, were recovered from L. carponotatus (Richardson), L. fulviflamma, L. fulvus (Forster), L. russellii, and L. vitta (Quoy & Gaimard) off Lizard Island, on the northern Great Barrier Reef (GBR). Neometadena paucispina is distinguished from N. ovata in having fewer oral spines (55–65 vs 67–80). Alignment of novel molecular data for these two taxa revealed that they differ consistently by 13 nucleotides (1.5%) over the partial large subunit (LSU), 34 nucleotides (6.6%) over the internal transcribed spacer 1 (ITS1), 0 nucleotides over the 5.8S, and 21 nucleotides (7.3%) over the ITS2 rDNA regions. Despite relatively large samples of L. carponotatus, L. fulviflamma and L. russellii from three distinct locations along the east coast of QLD (i.e. Moreton Bay in the south, Heron Island in central QLD and Lizard Island in northern QLD), these two species have been found at only one site each with neither species at Heron Island. These distributions are discussed in the context of the wide distribution of other cryptogonomid species in the same hosts elsewhere in the Indo-West Pacific.     

New species of pelagic eelpouts of the genus <Emphasis Type="Italic">Melanostigma</Emphasis> (Zoarcidae) from Western Antarctica

A new species, Melanostigma olgae sp. n., is described from the Southern Ocean. The type series was obtained along the South Sandwich Islands (Scotia Sea, Western Antarctic) at the depths of 800?850 m. The new species differs from the other representatives of Melanostigma genus by the original combination of the features of the seismosensory system, axial skeleton, and coloration. The homologization of the structural elements (senses) of the head canals of the lateral line has been done for the first time for the Melanostigma. Morphology of M. olgae allows considering this species as the most evolutionary advanced within the representatives of this genus inhabiting the Southern Ocean. The key of the Antarctic species of the genus Melanostigma is provided.     

Book review of Littler DM. Littler MM (2000) Caribbean Reef Plants An Identification Guide to the Reef Plants of the Caribbean,Bahamas, Florida and Gulf of Mexico

Information on spatial variability and distribution patterns of organisms in coral reef environments is necessary to evaluate the increasing anthropogenic disturbance of marine environments (Richmond 1993; Wilkinson 1993; Dayton 1994). Therefore different types of subtidal, reef-associated hard substrata (reef flats, reef slopes, coral carpets, coral patches, rock grounds), each with different coral associations, were investigated to determine the distribution pattern of molluscs and their life habits (feeding strategies and substrate relations). The molluscs were strongly dominated by taxa with distinct relations to corals, and five assemblages were differentiated. The Dendropoma maxima assemblage on reef flats is a discrete entity, strongly dominated by this encrusting and suspension-feeding gastropod. All other assemblages are arranged along a substrate gradient of changing coral associations and potential molluscan habitats. The Coralliophila neritoidea–Barbatia foliata assemblage depends on the presence of Porites and shows a dominance of gastropods feeding on corals and of bivalves associated with living corals. The Chamoidea–Cerithium spp. assemblage on rock grounds is strongly dominated by encrusting bivalves. The Drupella cornus–Pteriidae assemblage occurs on Millepora–Acropora reef slopes and is strongly dominated by bivalves associated with living corals. The Barbatia setigera–Ctenoides annulata assemblage includes a broad variety of taxa, molluscan life habits and bottom types, but occurs mainly on faviid carpets and is transitional among the other three assemblages. A predicted degradation of coral coverage to rock bottoms due to increasing eutrophication and physical damage in the study area (Riegl and Piller 2000) will result in a loss of coral-associated molluscs in favor of bivalve crevice dwellers in dead coral heads and of encrusters on dead hard substrata.     

Assessment of hybridisation between the endangered Chatham Island black robin (<Emphasis Type="Italic">Petroica traversi</Emphasis>) and the Chatham Island tomtit (<Emphasis Type="Italic">Petroica macrocephala chathamensis</Emphasis>)

Hybridisation between an endangered species and a more common species can facilitate population decline and extinction of the endangered species due to wasted reproductive effort, outbreeding depression and/or swamping of alleles due to widespread or complete admixture. The Chatham Island black robin (Petroica traversi) is an endangered songbird species, which was reduced to only five individuals in 1980. Intensive cross-fostering, whereby black robin offspring were placed into nests of the closely related Chatham Island tomtit (Petroica macrocephala chathamensis) to increase reproductive output, contributed to the rapid recovery of the species within 10 years. Several hybridisation events occurred and although those hybrids were successfully eliminated from the population, concerns remained for the possibility of introgression between the two species that may have gone unnoticed. In this study, we genotyped seven microsatellite loci in both species from the two islands where they coexist, to assess the level of hybridisation and the extent of introgression between the two species. The two species shared no alleles at five of the seven loci genotyped, and cluster analysis, AMOVA and admixture analysis of a total of 174 black robins and 78 Chatham Island tomtits showed no evidence of hybridisation or introgression on either of the two islands where they co-exist. As a result, there is no evidence that black robins are currently in any danger of population decline or extinction through hybridisation with tomtits, although small population size and skewed sex ratio, particularly in the smaller of the two populations, may facilitate future hybridisation events.     

Near-future ocean acidification enhances the feeding rate and development of the herbivorous juveniles of the crown-of-thorns starfish, <Emphasis Type="Italic">Acanthaster planci</Emphasis>

Population outbreaks of the corallivorous crown-of-thorns starfish, Acanthaster planci, are a major contributor to the decline in coral reef across the Indo-Pacific. The success of A. planci and other reef species in a changing ocean will be influenced by juvenile performance because the naturally high mortality experienced at this sensitive life history stage maybe exacerbated by ocean warming and acidification. We investigated the effects of increased temperature and acidification on growth of newly metamorphosed juvenile A. planci and their feeding rates on crustose coralline algae (CCA) during the initial herbivorous phase of their life history. The juveniles were exposed to three temperature (26, 28, 30 °C) and three pH (NIST scale: 8.1, 7.8, 7.6) levels in a flow-through cross-factorial experiment. There were positive but independent effects of warming and acidification on juvenile growth and feeding. Early juveniles were highly tolerant to moderate increases in temperature (+2 °C above ambient) with the highest growth at 30 °C. Growth and feeding rates of A. planci on CCA were highest at pH 7.6. Thus, ocean warming and acidification may enhance the success of A. planci juveniles. In contrast to its coral prey, at this vulnerable developmental stage, A. planci appears to be highly resilient to future ocean change. Success of juveniles in a future ocean may have carry-over effects into the coral-eating life stage, increasing the threat to coral reef systems.     

Skeletal dissolution kinetics and mechanical tests in response to morphology among coral genera

Ocean acidification is widely accepted as a primary threat to coral reef populations. Negative physiological effects include decreased calcification rates, heightened metabolic energy expenditure, and increased dissolution of coral skeletons. However, studies on the dissolution of coral skeletons structures under ocean acidification conditions and their implications on sediments remain scarce. In this work, we examined skeletal dissolution kinetics from four of the most representative hermatypic corals of the Eastern Pacific coasts (Pocillopora, Porites, Pavona, and Psammocora). Samples were treated with a highly acidic solution for defined periods of time, and measurements of dissolved calcium ([Ca⁺²]) were used to evaluate the kinetics of coral skeleton dissolution. All genera tests except Porites showed a zero reaction rate. Porites exhibited a first-order reaction and a faster reaction rate than other genera. Compression strength tests and skeletal density did not correlate with reaction rate. Pavona showed greater structural strength. Porites were the most susceptible to acidic dissolution compared to other genera tested due to their morphology, i.e., possession of the largest surface area, suggesting a high vulnerability under low-pH conditions. The hierarchical response in dissolution kinetics among coral genera tested suggests that the most soluble coral might act as a buffer under ocean acidification conditions.     

<Emphasis Type="Italic">Bruguiera hainesii</Emphasis>, a critically endangered mangrove species,is a hybrid between <Emphasis Type="Italic">B. cylindrica</Emphasis> and <Emphasis Type="Italic">B. gymnorhiza</Emphasis> (Rhizophoraceae)

Bruguiera hainesii (Rhizophoraceae) is one of the two Critically Endangered mangrove species listed in the IUCN Red List of Threatened Species. Although the species is vulnerable to extinction, its genetic diversity and the evolutionary relationships with other Bruguiera species are not well understood. Also, intermediate morphological characters imply that the species might be of hybrid origin. To clarify the genetic relationship between B. hainesii and other Bruguiera species, we conducted molecular analyses including all six Bruguiera species using DNA sequences of two nuclear genes (CesA and UNK) and three chloroplast regions (intergenic spacer regions of trnL-trnF, trnS-trnG and atpB-rbcL). For nuclear DNA markers, all nine B. hainesii samples from five populations were heterozygous at both loci, with one allele was shared with B. cylindrica, and the other with B. gymnorhiza. For chloroplast DNA markers, the two haplotypes found in B. hainesii were shared only by B. cylindrica. These results suggested that B. hainesii is a hybrid between B. cylindrica as the maternal parent and B. gymnorhiza as the paternal one. Furthermore, chloroplast DNA haplotypes found in B. hainesii suggest that hybridization has occurred independently in regions where the distribution ranges of the parental species meet. As the IUCN Red List of Threatened Species currently excludes hybrids (except for apomictic plant hybrids), the conservation status of B. hainesii should be reconsidered.