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Corals live with complex assemblages of microbes including bacteria, the dinoflagellate Symbiodiniaceae, fungi and viruses in a coral holobiont. These coral-associated microorganisms play an important role in their host fitness and survival. Here, we investigated the structure and diversity of algal and bacterial communities associated with five Indo-Pacific coral species, using full-length 16S rRNA and internal transcribed spacer sequences. While the dinoflagellate communities associated with Poriteslutea were dominated with Symbiodiniaceae genus Cladocopium, the other four coral hosts were associated mainly with members of the Durusdinium genus, suggesting that host species was one of the underlying factors influencing the structure and composition of dinoflagellate communities associated with corals in the Gulf of Thailand. Alphaproteobacteria dominated the microbiomes of Pocillopora spp. while Pavonafrondifera and P. lutea were associated primarily with Gammaproteobacteria. Finally, we demonstrated a superior performance of full-length 16S rRNA sequences in achieving species-resolution taxonomic classification of coral-associated microbiota.

Coral reefs are declining at an unprecedented rate as a consequence of local and global stressors. Using a 26-year monitoring database, we analyzed the loss and recovery dynamics of coral communities across seven islands and three archipelagos in French Polynesia. Reefs in the Society Islands recovered relatively quickly after disturbances, which was driven by the recovery of corals in the genus Pocillopora (84% of the total recovery). In contrast, reefs in the Tuamotu and Austral archipelagos recovered poorly or not at all. Across archipelagos, predation by crown-of-thorns starfish and destruction by cyclones outweighed the effects of heat stress events on coral mortality. Despite the apparently limited effect of temperature-mediated stressors, the homogenization of coral communities towards dominance of Pocillopora in the Society Archipelago and the failure to fully recover from disturbances in the other two archipelagos concern the resilience of Polynesian coral communities in the face of intensifying climate-driven stressors.

Ongoing climate change and frequent anomalous thermal events have greatly contributed to the deterioration of coral reefs worldwide, exacerbating declines in coral reef formation and ecosystem service provision. Under this climate change scenario, the development and improvement of restoration techniques will be required to cope with coral reef degradation. This study demonstrates the potential use of direct relocation of coral of opportunity as an effective long-term ecological restoration tool. We assessed coral growth parameters (cm yr−1), attachment rate (%), ecological volume (cm3 yr−1), including long-term evaluation of annual live coral cover (%) and calcium carbonate production (kg CaCO3 m−2 yr−1) during 5-years (2013–2018) using resilient branching coral Pocillopora spp. The results show a survivorship of 67%, high self-attachment (100%) during the first 6-months, and size augmentation of ∼167% in growth parameters (2.94–4.47 cm yr−1) and ∼418% in ecological volume. Over the long-term, live coral cover increased from 13 to 28% (+4% per year) with an accumulated carbonate production of 14.53 kg CaCO3 m−2 (∼3 kg CaCO3 m−2 yr−1) resulting from the restoration process, and we found evidence for high resistance and recovery after periods of thermal anomalies. The data validate the use of direct propagation of corals of opportunity as a one of the most feasible and practical techniques to long-term restoration of damaged and degraded coral reef areas, which may help in their structural rehabilitation, improving coral communities and biodiversity maintenance.

Pollution of marine environments with microplastic particles (i.e. plastic fragments

Coral reefs are formed by living polyps, and understanding the dynamic processes behind reef stones is crucial for marine ecological restoration. However, these processes are still unclear because the growth and budding patterns of living polyps are poorly known. Here, we investigate the growth pattern of a prevalently distributed reef-building coral Pocillopora damicornis from Xisha Islands using high-resolution computed tomography. We examine the budding, growth, and distribution pattern of polyps in a single coral stone and reconstruct the growth pattern of the entire polyp network. The results reveal that the three-stage growth pattern of P. damicornis is based on multiple types of polyps forming growth bundles along dichotomous growth axes. Our work on the three-dimensional structures of polyps sheds new light on the process of coral reef formation and suggests that Pocillopora is an important animal model for studying the growth and budding patterns of living polyps.

The hermatypic coral ecosystems of the southern coast of Jalisco, Mexico, present an important species richness and coverage for the Mexican Central Pacific. However, knowledge of these ecosystems of the Jalisco coast is fragmented. Studies have concentrated on few localities, employing a limited number of coral health indicators, and gaps still remain in the knowledge of ecosystem structure and its local and mesoscale variation. This study evaluated spatial variations in the coral assemblage structure in six sites on the southern coast of Jalisco, Mexico, five of which had never been studied before. Sampling was conducted in September 2019, utilizing a total of 35 transects (each of 25 m in length). The cover of each coral species was recorded, as well as other benthic groups and substrate types. Different community attributes, patterns of similarity in coral species and their relationships with the benthic habitat structure were evaluated in each site. The results showed that the observed richness (8 species) represented 83.7% of that expected by chance. Significant spatial variation was found between coral patch sites and coral community sites, in terms of species richness, Shannon diversity and live coral cover, as well as in the structure of the coral assemblage and the benthic habitat. The results evidenced these conditions despite the existence of a considerable dominance of branched corals of the genus Pocillopora. The species that contributed most to the differences between coral patch sites and coral community sites were Pocillopora damicornis, Pocillopora capitata and Pocillopora verrucosa. For their part, the benthic habitat structural elements that favored the differences between site conditions were live coral cover and turf.

Coral reefs are considered to be valuable ecosystems due to the goods and services that they provide. However, these ecosystem services are highly dependent on the physical structure of the reef, which in turn depends on the species composition of hermatypic corals. In this study, we explored the functional potential of reefs with a new index that takes into account coral cover, the calcification rate, rugosity, and the height of each species. In June 2019, we surveyed 11 reefs from the southern Mexican Pacific (15°40′N, 96°29′W−15°45′N, 96°5′W) to estimate coral cover and collect quantitative morphometric data of ~15 haphazardly selected coral colonies per site (N = 102). We estimated the calcification rates and structural complexity of the species present and then calculated the Reef Functional Index (RFI), which estimates the species-specific functional contribution of the corals in reef systems by integrating their capacity to create complex three-dimensional structures through calcium carbonate precipitation with morphological complexity. We modelled the effects of shifting species compositions through a permutation approach with 6435 possible combinations. We found a mean coral cover of 48.5 ± 18.09% (±SD) dominated by Pocillopora damicornis, Pocillopora verrucosa, and Pocillopora capitata and low abundance of Porites panamensis and Pavona gigantea. The mean RFI was 0.71 ± 0.1. The permutation model showed that the RFI was very close to its maximum potential (96%) when the relative abundance of pocilloporids was ≥60% and decreased as the relative abundance of massive corals increased. At maximum evenness, the RFI value was at 92% of its maximum potential. Our data highlight the importance of pocilloporids to the functioning of reefs in the Eastern Tropical Pacific (ETP) and confirm that P. damicornis is the primary reef builder in the region. Nevertheless, our findings also highlight the vulnerability of these reefs given that branching corals are more susceptible to environmental disturbance than slow-growing massive corals. In a rapidly changing environment, the future of ETP reefs depends not only on the survival of pocilloporids but also on the ability of coral reefs to withstand highly variable oceanographic conditions as complete ecosystems.

Corals routinely lose tissue due to causes ranging from predation to disease. Tissue healing and regeneration are fundamental to the normal functioning of corals, yet we know little about this process. We described the microscopic morphology of wound repair in Pocillopora damicornis. Tissue was removed by airbrushing fragments from three healthy colonies, and these were monitored daily at the gross and microscopic level for 40days. Grossly, corals healed by Day 30, but repigmentation was not evident at the end of the study (40d). On histology, from Day 8 onwards, tissues at the lesion site were microscopically indistinguishable from adjacent normal tissues with evidence of zooxanthellae in gastrodermis. Inflammation was not evident. P. damicornis manifested a unique mode of regeneration involving projections of cell-covered mesoglea from the surface body wall that anastomosed to form gastrovascular canals.

The responses of reef benthic substrata and coral communities to anthropogenic disturbances at the Wuzhizhou Island (WZZ, off the southeast coast of the Hainan Island in the South China Sea) were examined in 2007–2017. A total of 90 scleractinia coral species were recorded at WZZ in 2017. Cluster analysis and ANOSIM analysis of reef benthic composition suggested that WZZ can be divided into the north and south zones with significantly different characteristics. Indeed, anthropogenic disturbance (i.e., tourism activity and land use) has been intense in the north zone, whereas the south zone has not been as much disturbed. Coral reefs in the north zone suffered from stronger turbidity and nutrient enrichment. Compared with the south zone, the north zone had significantly lower coverage of stony coral (e.g. Acropora, Montipora and Pocillopora) and soft coral, juvenile coral density but significantly higher coverage of rock/rubble, sand, hydrocoral and sponge. Redundancy analysis demonstrated that turbidity and dissolved nutrients (dissolved inorganic nitrogen or NH4+) were the significant factors in explaining the spatial distribution of reef benthic substrata and coral communities in 2017. The remarked decline of live coral cover in the north zone of WZZ during 2007–2016 can be associated with intensive construction, land use change, and tourism development. These results suggested that anthropogenic disturbances may have degenerated environmental conditions and affected the coral reefs at WZZ.

Corals are comprised of a coral host and associated microbes whose interactions are mediated by the coral innate immune system. The diversity of immune factors identified in the Pocillopora damicornis genome suggests that immunity is linked to maintaining microbial symbioses while also being able to detect pathogens. However, it is unclear which immune factors respond to specific microbe-associated molecular patterns and how these immune reactions simultaneously affect coral-associated bacteria. To investigate this, fragments of P. damicornis and P. acuta colonies from Taiwan were subjected to lipopolysaccharide (LPS) treatment to stimulate immune responses and measure bacteria community shifts. RNA-seq revealed genotype-specific immune responses to LPS involving the upregulation of immune receptors, transcription factors, and pore-forming toxins. Bacteria 16S sequencing revealed significantly different bacteria communities between coral genotypes but no differences in bacteria communities were caused by LPS. Our findings confirm that Pocillopora corals activate conserved immune factors in response to LPS and identify transcription factors coordinating Pocillopora corals’ immune responses. Additionally, the strong effect of coral genotype on gene expression and bacteria communities highlights the importance of coral genotype in the investigation of coral host-microbe interactions.

The frequency and intensity of marine heatwaves that result in coral bleaching events have increased over recent decades and led to catastrophic losses of reef-building corals in many regions. The high-latitude coral assemblages at Lord Howe Island, which is a UNESCO listed site is the world southernmost coral community, were exposed to successive thermal anomalies following a fast phase-transition of the record-breaking 2009 to 2010 warm pool El Nino in the Central Pacific to a strong La Nina event in late 2010. The coral community experienced severe and unprecedented consecutive bleaching in both 2010 and 2011. Coral health surveys completed between March 2010 and September 2012 quantified the response and recovery of approximately 43,700 coral colonies to these successive marine heatwaves. In March 2010, coral bleaching ranged from severe, with 99% of colonies bleached at some shallow lagoon sites, to mild at deeper reef slope sites, with only 17% of individuals affected. Significant immediate mortality from thermal stress was evident during the peak of the bleaching event. Overall, species in the genera Pocillopora, Stylophora, Seriatopora and Porites were the most affected, while minimal bleaching and mortality was recorded among members of other coral families (e.g. Acroporidae, Dendrophyllidae & Merulinidae). Surviving corals underwent a subsequent, but much less intense, thermal anomaly in 2011 that led to a disproportionate bleaching response among susceptible taxa. While this observation indicates that the capacity of thermally susceptible high-latitude corals to acclimatize to future ocean warming may be limited, particularly if bleaching events occur annually, our long-term survey data shows that coral cover at most sites recovered to pre-bleaching levels within three years in the absence of further thermal anomalies.

In the gardening approach for reef restoration, coral stocks are farmed in underwater nurseries (phase I) prior to their transplantation onto degraded reefs (phase II). The phase I aspects were already evaluated in the literature, but very little is known about the phase II outcomes. Assessing phase II feasibility, we transplanted 554 nursery-farmed colonies of two branching species (Stylophora pistillata, Pocillopora damicornis) onto five denuded knolls in Eilat (Red Sea). The performance of the transplants was compared for 17 months with 76 natal colonies and 217 colonies maintained at the coral-nursery. At the natural reef, rates of full/partial mortalities, detachment and fish herbivory were considerably higher than the nursery values. While corallivory on Pocillopora transplants was comparable to that observed in natal colonies, herbivory on Stylophora transplants increased 2.2 fold compared to natal controls. Their survivorship was similar to the survivorship observed in natal colonies in the 9 months post transplantation, but was 30% higher after 17 months. In contrast, no enhanced mortality was documented in Pocillopora transplants throughout the entire period. The detachment levels of the Stylophora and Pocillopora transplants were 3 and 10 times higher, respectively, than those observed in natal colonies, and the growth rates of the transplants were identical to the rates observed in the nursery control groups. Transplants showed a 2.5–3.3 fold increase in colonial ecological-volumes, resulting in enhanced acquired space/habitats for coral-dwelling species like Trapezia, Alpheus, Spirobranchus and Lithophaga. The successful integration of farmed transplants in Eilat’s degraded reef and their provision of new ecological niches for reef-associated fauna, coupled with economic assessments, indicate that transplantation of farmed corals is an easy, cost-effective mean to counteract degradation of coral reefs. Results also imply that the selection of coral species for reef restoration should take into consideration their autogenic/allogenic engineering properties, particularly if the aims are to restore the whole reef community, rather than simply focus on coral coverage.

Facing the worldwide coral degradation, active restorations are moving toward improving techniques to maintain coral coverage. Transplant methods have been used to restore coral reef areas that were completely degraded; however restoration is not commonly employed at coral reefs with evident loss that may jeopardize the maintenance of the community. In this study the re-attachment concept using the natural fragmentation of branched-corals was tested as an accelerator process to natural recovery based on asexual reproduction. Survivorship, growth and attachment rates of three Pocillopora species on both natural and artificial substrates were evaluated at four sites of Islas Marietas. Over one year of monitoring during 2012–2013, resulted in a high survivorship of 87% on artificial underwater structures and 67% on natural substrate, the height and radial growth, on both substrata increase 2-fold from the initial size; although both substrata were viable, coral fragments attach faster on natural (4 months) than artificial structures (6 months). The results demonstrate that re-attachment using natural substrata is a potential and no invasive instrument for treating coral reefs not completely degraded in restoration programs.

The transplantation is an important method for the restoration of degraded ecosystem. However, it is unclear how the choice of species and transplantation mode affects the community dynamics during recovery from a disaster, particularly for long-lived organisms such as corals. To address this issue, we study a population dynamic model of multiple species in multiple habitats connected by larval dispersal. We first consider two species showing the trade-off relationship between growth rate and mortality and examine three restoration goals to evaluate the effectiveness of transplantation: (1) total coverage; (2) species diversity; (3) spatial heterogeneity of species composition. To promote the rapid development of total coverage, the transplantation of fast-growing species should be adopted. To maintain a high level of regional species diversity, the transplantation of slow-growing species or short-dispersal species is effective. Next, we suppose four genera of corals – Acropora, Pocillopora, Porites, and Favites – as an example of coral community in Okinawa where Pocillopora is facing to local extinction. In addition to three indexes; (4) recovery of locally endangered species is evaluated as a restoration goal. Results show that to promote the recovery of Pocillopora, the transplantation of the same species is clearly the most effective choice. In contrast, the transplantations of Acropora and Porites led to undesirable results. In summary, these results indicate that both the restoration goal and the transplanted species must be carefully selected before conducting transplantation operations.

An opportunity to explore the effects of fluctuating temperatures on tropical scleractinian corals arose when diurnal warming (as large as 4.7 °C) was detected over the rich coral communities found within the back reef of Moorea, French Polynesia. In April and May 2007, experiments were completed to determine the effects of fluctuating temperature on Pocillopora meandrina and Porites rus , and consecutive trials were used to expose them for 13 days to 26 °C, 28 °C (ambient conditions), 30 °C, or a fluctuating treatment ranging from 26 to 30 °C over 24 h. The multivariate response was assessed using maximum dark-adapted quantum yield of PSII (F V /F M ), Symbiodinium density, chlorophyll-a content, and calcification. In trial 1, multivariate physiology of both species was significantly affected by treatments, with the fluctuating temperature resulting in a 17–45% decline in Symbiodinium density (relative to the ambient) matching that occurring at a constant 30 °C; F V /F M , chlorophyll-a content, and calcification, did not differ between the fluctuating and the steady treatments. In contrast, in trial 2 that utilized corals collected two weeks after those used in trial 1, the corals were unaffected by the treatments, likely due to an environment × trial interaction caused by seasonal declines in Symbiodinium density. Together, these results demonstrate that short transgressions to ecologically relevant high and low temperatures can elicit a potentially detrimental response equivalent to that occurring upon exposure to a constant high temperature. The dissimilar responses among dependent variables and consecutive trials underscore the importance of temporal replication and multivariate approaches in coral ecophysiology. It is likely that recent history has a stronger effect on the response of corals to treatments than is currently recognized.

Recent research has shown that heterotrophic feeding has a strong effect on both maintenance and growth of corals by providing mainly a nutritional source of nitrogen and phosphorus. Nevertheless, no study has yet been undertaken on the interactions between feeding and sexual reproduction in corals. This study examines the effects of heterotrophic feeding on the sexual reproduction of Pocillopora verrucosa in aquaria. Rotifers were used as a live food source at two concentrations ((LFC = low feed colonies) = 5 × 10 2 organisms l − 1 ; (HFC = high feed colonies) = 15 × 10 2 organisms l − 1 ) with an unfed control (UC = unfed colonies). Three replicates of five colonies were used for each treatment. Rotifers were distributed among the nine aquaria four times per week for 3 h. Histological sections of coral polyps were prepared to monitor the development of gametogenic stages and the fecundity of the colonies. The number and size of oocytes, sperm sacs and gonad stages were determined in each polyp. Both fed and starved colonies of P. verrucosa proved to be simultaneous hermaphrodites and broadcast spawners. The gametogenesis period was short (3 months) and occurred from October to December 2007. No spawning event was observed in the aquaria. However, the disappearance of mature oocytes in samples collected in January 2008 suggested that spawning took place between December 2007 and January 2008. Heterotrophic feeding appeared to have a negative effect on reproduction in P. verrucosa . The results showed that both the proportion of polyps with gametes and the reproductive effort were lower in the fed than in starved colonies. It is likely that an energetic trade-off occurred between reproduction and other metabolic functions. However, oocytes were bigger in fed corals compared with the unfed controls. Several hypotheses are proposed to explain these metabolic/energy distribution patterns.

Coral communities from the Central Mexican Pacific have suffered regional bleaching as a consequence of temperature anomalies stemming from El Nino Southern Oscillation events and local events. Due to these and other impacts, there is an urgent need to better understand the physiological response of reef corals to changes in their external environment. In this study, we measured lipid content and endosymbiont densities in colonies of the common, reef-building coral Pocillopora verrucosa in order to gauge their response to thermal stress, in particular, over a multi-month time span. Colonies were collected from different depths and different sites in the same area in three different periods. In coral colonies from the southern site, both markers varied temporally over the course of the year, though no variation was found between colonies from different depths. In colonies from the northern site, total lipid content varied significantly between depths and over time. The northern colonies which had been seriously affected by the cold water bleaching appear to be more sensitive to stress events than those from the southern site, which demonstrated an acclimatization response to the elevated temperatures to which they were exposed. And also different colonies were collected and acclimatized in laboratory aquaria and exposed to thermal stress (28 and 31 °C). Only colonies exposed to 31 °C experienced a significant decrease in total lipid content within their cells. Likewise, these colonies also demonstrated a statistically significant 82% reduction in density of endosymbiotic dinoflagellates (genus Symbiodinium). A better understanding of the ability of corals to acclimatize to different temperature regimes will allow managers to target particular reef ecosystems for enhanced protection under future periods of thermal stress, namely those expected to be brought on by global climate change.

Holocene sea-level change provides direct evidence of the melting of ice sheets; however, our understanding of the timing and course of such change is limited by a lack of information regarding environmental condition of corals. For example, Holocene sea-level curves are compiled based on water depths estimated from the occurrence of a small number of coral species, as species identification is difficult work. The error associated with this method of estimating sea level exceeds ± 2.5 m. In addition, there generally occurs a difference in the living-water depth of corals between high-energy reefs and low- to moderate-energy reefs. This difference in living-water depth also results in an error in reconstructed sea-level curves. In the present study, we analyzed drill core and recorded the vertical distribution of corals at the high-energy Ibaruma reef and low- to moderate-energy Fukido reef, Ishigaki Island, Ryukyu Islands, Japan. Analyses of corymbose Acropora (A. digitifera), massive Goniastrea (G. retiformis), massive Pocillopora (P. verrucosa), massive Platygyra (P. ryukyuensis), and other corals enables the accurate reconstruction of a sea-level curve because these species are distributed in a narrow range, with a weighted mean (Mw) error of between ± 0.5 and ± 2.5 m. These observation data from Ibaruma and Fukido reefs can be used to reconstruct Holocene sea-level curves based on drill core data from Ibaruma reef; however, the two reefs yield contrasting sea-level curves: the curve reconstructed based on data from Fukido reef is several meters deeper than that reconstructed based on data from Ibaruma reef. This discrepancy reflects the different energy levels of the two reefs (high-energy at Ibaruma reef and low- to moderate-energy at Fukido reef). Therefore, the accurate reconstruction of a Holocene sea-level curve requires the identification of species from drill core and observations of the vertical distribution of species at the present-day reef at a location close to the drilling site. The Holocene sea-level curve reconstructed based on drill core data from Ibaruma reef reveals a rapid sea-level rise of approximately 7.5 m kyr− 1 between 8000 and 6000 cal. years BP. The rate of sea-level rise decreased from 7.5 to 3.5 m kyr− 1 between 6000 and 5000 cal. years BP. A mid-Holocene highstand occurred at around 5000 cal. years BP, at a level of approximately 3 ± 2.5 m above the present mean sea level. The increase in ocean volume corresponding to this sea-level rise indicates that melting of the Antarctic ice sheet continued beyond 6000 cal. years BP, as most of the Northern Hemisphere ice sheets had melted by 6000 cal. years BP, resulting in sea levels similar to those of the present day.

Ecological research within coral reefs often requires the use of anesthetics to immobilize organisms. It is therefore important to consider the effect of these chemicals on the surrounding flora and fauna, particularly to the corals themselves. We quantified the effects of clove oil, a commonly used fish anesthetic, on the growth and occurrence of bleaching in three species of corals: Acropora striata, Pocillopora verrucosa, and Porites australiensis. We compared coral responses to five treatments: a gradient of four clove oil concentrations (0-28%) in seawater, and one concentration of clove oil (14%) in ethanol. Each week, we assessed the presence of bleaching, and then applied the treatment. We measured growth over the duration of the 6-week experiment using the buoyant weight technique. Growth and bleaching showed a dose response to clove oil exposure, and the use of ethanol as a solvent had an additional deleterious effect, as also suggested by observed changes in concentrations of eugenol following field application. Overall, growth was reduced by 37.6% at the highest concentration (28% clove oil in seawater) relative to the control (0% clove oil). The reduction in growth was nearly as great (35.3% of the control) at half the concentration of clove oil (14%) when dissolved in ethanol. These results suggest the repeated use of clove oil (even without a solvent) can deleteriously affect corals.

International audience; Several environmental factors have been described to trigger bleaching in cnidarian/dinoflagellate endosymbiosis. However, the molecular mechanisms underlying this process still need more investigations. Symbiosis breakdown is known to result from physiological damage to animal host cells and/or symbionts. Cellular oxidation appears to be an essential player in this damage. Indeed, oxidative stress is a direct consequence of increase in irradiance and temperature, the two main environmental factors involved in bleaching. In this study, we examined the role of irradiance in inducing dissociation and oxidative stress in cnidarians and dinoflagellates. We used the bleaching-sensitive scleractinian coral previous termPocilloporanext term verrucosa in a field cross-transplantation experiment performed between 5 m and 20 m depth at Grande Glorieuse Island (Indian Ocean), a preserved area subject to minimal anthropogenic influence. Cellular damage and increase in antioxidant defense were correlated with bleaching in upward transplanted samples. Downward transplanted colonies presented no associated alterations similar to the controls. We therefore conclude that increasing light induced bleaching via a prooxidative period. Remarkably, the distribution of Symbiodinium over depth was invariant; all colonies were monomorph for clade C, suggesting that bleaching sensitivity of P. verrucosa might not be associated with clade specificity

To examine the response to exposure to a thermal gradient in coral, we assessed the effect of a gradual 10 degrees C temperature increase (22 to 32 degrees C over 10 h) on normal (N), partially bleached (P) and control (C) samples collected from different branches of the same coral (Pocillopora capitata). We examined markers of oxidative stress, including lipid peroxidation (MDA) and superoxide dismutase (SOD) activity, indicators of bleaching, including chlorophyll a (Chl a) and carotenoid pigment (PC) levels, as well as zooxanthellae density. Our results revealed that N, P and C coral samples all contained higher levels of PC versus Chl a. The levels of both pigments increased as the temperature increased from 22 to 28 degrees C only in N and C samples, whereas P samples showed less cellular damage than N and C samples at temperatures between 26 and 28 degrees C, and had greater antioxidant activities at temperatures between 26 and 30 degrees C. The rate of zooxanthellar expulsion consistently increased with temperature in all three coral types across the entire temperature range. Collectively, these results indicate that temperature has a direct effect on the antagonistic relationship between temperature-induced damage and protective antioxidant mechanisms in this type of coral.

A population of the scleractinian coral Pocillopora damicornis (Linnaeus) was examined at Rottnest Island, off the Western Australian coast. This is a temperate zone and an area under considerable tourist pressure. Experiments were conducted at Little Salmon Bay and Mary Cove to investigate the effect of mechanical damage on the growth, reproduction and storage of lipid to see whether patterns of energy allocation were affected. These parameters were measured simultaneously 14 times over 13 months. Damage had an adverse effect on the performance of the corals. Dislodged corals had increased mortality, decreased growth, decreased reproduction but no change in lipids. Fragmented corals had no significant change in mortality, lipids or growth rate but had increased reproduction. The overall allocation of energy to growth, reproduction and lipid storage of dislodged corals appeared to decrease whereas the overall output of the fragmented corals has increased.

The Waimanalo Formation (limestone) of Oahu has been correlated with the last interglacial period based on U-series dating of corals by T.-L. Ku and colleagues. The limestone consists of growth-position corals and overlying coral conglomerate. An apparent bimodal distribution of ages for the growth-position corals (mean age = 133 ka) and the overlying coral conglomerate (mean age = 119 ka) has been interpreted to represent two distinct high stands of sea that occurred within the last interglacial period. Both growth-position corals and overlying, conglomerate coral occur in an outcrop east of Kaena Point and consist mainly of Pocillopora and Porites . U-series ages of growth-position corals that show closed-system conditions are 120 ± 3 ka and 127 ± 4 ka; overlying conglomerate corals have U-series ages that range from 120 ± 3 ka to 138 ± 4 ka. At Kahe Point, conglomerate corals have ages of 120 ± 3 ka and 134 ± 4 ka. These data show that the growth position corals are not systematically older than the conglomerate corals; thus, there is no evidence for two distinct high stands of sea. Waimanalo deposits at Kahe Point and Mokapu Point (new U-series ages of 134 ± 4 ka and 127 ± 3 ka) have beach deposits as high as 12.5 m and, at Mokapu Point, growth-position corals as high as 8.5 m. A last-interglacial sea-level stand of +8.5 to +12.5 m conflicts with estimates of +6 m from a number of tectonically stable coastlines and islands in the western Atlantic Ocean. We infer, therefore, that Oahu may be undergoing uplift at a low rate. This uplift may be due to compensatory lithospheric flexure, because the island of Hawaii has been subsiding throughout much of the Quaternary from volcanic loading. Because of this possible uplift, Oahu and islands like it elsewhere in the Pacific cannot be used as reference points for sea level during the last interglacial period.

Experimental manipulations were carried out to determine the short-term and long-term results of interspecific aggression by means of extracoelenteric digestion between two reef-building corals, Cyphastrea ocellina (Dana) and Pocillopora damicornis (Linnaeus). Short-term interactions between these two corals result in tissue damage to P. damicornis by C. ocellina. The long-term results of interactions between these two species are quite different from the short-term results. The short-term winner, C. ocellina, has lower linear growth and lower skeletal weight increase over 11 months when interacting with P. damicornis than when growing alone. The growth of the short-term loser, P. damicornis, is not quantitatively affected by interactions although it does redirect growth away from the zone of interaction. These results suggest that fighting among corals is energetically costly. Although the response of C. ocellina to an interaction with another coral is the use of a specific aggressive mechanism that has a negative effect on its growth, this response allows C. ocellina to survive in the presence of a superior growth competitor. The response of P. damicornis, to redirect growth away from the zone of contact with C. ocellina, does not have a high energetic cost but it is sufficient for escaping an interaction. The high energetic cost of a specific aggressive mechanism may be used to explain how complicated, discriminatory hierarchical interactions can evolve among these relatively simple organisms.

Dascyllus aruanus (L.) and Pomacentrus amboinensis (Bleeker) are small and abundant planktivorous fishes that colonize small patch reefs in One Tree Lagoon (Great Barrier Reef, Australia). The former prefers a live Pocillopora damicornis (L.) coral substratum, and the latter is more common on Porites sp. reefs, whether live or dead. This paper describes an experiment which tests for effects of Pocillopora and Porites substrata on the survival and growth of juveniles of these two fish species. It also examines the outcomes of intra- and interspecific competition on these two coral types. Coral substratum was found to have much greater effects than competition on juvenile survival over a 1-yr period, with greater numbers of both fish species surviving on Pocillopora reefs. There were no indications of competitive dominance of one fish species over another, or a reversal of dominance in relation to substratum type. Slight positive effects of density on survival were obtained in P. amboinensis , and slight negative effects were apparent in D. aruanus . Effects of coral substratum on growth were less clear, although there is some suggestion that both species grow better on Pocillopora reefs. There were substantial effects of intraspecific competition on growth in P. amboinensis , but not in D. aruanus , and no effects of interspecific competition on growth in either species. Overall, the experiment suggests that the factors controlling growth and mortality are complex, and highlights the need for further multifactorial studies focused at the level of the species.

Several traits were examined in four potential coral prey species (colony form, organic matter content, caloric density, tissue accessibility, mucus release, cnidocyst composition, toxicity, and colony defense by crustacean coral guards) to help understand the feeding preference of the Hawaiian asteroid corallivore Culcita novaeguineae Muller & Troschel. In laboratory experiments, C. novaeguineae exhibits a preference for Pocillopora damicornis (L.) and Pocillopora meandrina Dana over Porites compressa Dana, Montipora verrucosa (Lamarck) and Fungia scutaria (Lamarck). The feeding rate of Culcita novaeguineae on Pocillopora damicornis was ≈ 28 cm 2 or 250 cm 3 per day. In limited field observations, a preference was shown by Culcita novaeguineae for small colonies of Pocillopora meandrina which were totally killed (all tissues removed from branches) after attack by the sea star. Although the organic matter content (mg dry wt/cm 3 ) of Pocillopora was the lowest of the four corals, the percent loss of organic matter after feeding (“utilization” by Culcita ) was the highest. This high intake of organic matter corresponds with the superficial location of the tissue layers and the ease of removal of tissues (by “water piking”) in Pocillopora compared with the other corals. Small colonies of Pocillopora are eaten more frequently than large colonies; the former harbor relatively low numbers of crustacean guards (crabs and shrimp) and their guards are small compared with large colonies. Coral mortality caused by Culcita ( 1.0 m 2 /yr) is only about one-fifth of that by Acanthaster (5.3 m 2 /yr), but the selective feeding of Culcita on Pocillopora , and its avoidance of nonpocilloporid corals, could affect significantly the relative abundance of corals in Hawaiian reef assemblages.