Metabolic and immune costs balance during natural acclimation of corals in fluctuating environments.

Epigenetic modifications based on DNA methylation can rapidly improve the potential of corals to adapt to environmental pressures by increasing their phenotypic plasticity, a factor important for scleractinian corals to adapt to future global warming. However, the extent to which corals develop similar adaptive mechanisms and their specific adaptation processes remain unclear. Here, to reveal the regulatory mechanism by which DNA methylation improves thermal tolerance in Pocillopora damicornis under fluctuating environments, we analyzed genome-wide DNA methylation signatures in P. damicornis and compared the differences in the methylation and transcriptional responses of P. damicornis from fluctuating and stable environments using whole-genome bisulfite sequencing and nanopore-based RNA sequencingtranscriptome sequencing. We discovered low methylation levels in P. damicornis (average methylation 4.14%), with CpG accounting for 74.88%, CHH for 13.27%, and CHG for 11.85% of this methylation. However, methylation levels did not change between coral samples from the fluctuating and stable environments. The varied methylation levels in different regions of the gene revealed that the overall methylation level of the gene body was relatively high and showed a bimodal methylation pattern. Methylation occurs primarily in exons rather than introns within the gene body In P. damicornis, there was only a weak correlation between methylation and transcriptional changes at the individual gene level, and the methylation and gene expression levels generally exhibited a bell-shaped relationship, which we speculate may be due to the specificity of cnidarian species. Correlation analysis between methylation levels and the transcriptome revealed that the highest proportion of the top 20 enriched KEGG pathways was related to immunity. Additionally, P. damicornis collected from a high-temperature pool had a lower metabolic rate than those collected from a low-temperature pool. We hypothesize that the dynamic balance of energy-expenditure costs between immunity and metabolism is an important strategy for increasing P. damicornis tolerance. The fluctuating environment of high-temperature pools may increase the heat tolerance in corals by increasing their immunity and thus lowering their metabolism.

Feeding responses of reef-building corals provide species- and concentration-dependent risk assessment of microplastic.

The negative impacts of microplastic on reef-building corals are often attributed to the feeding responses to these particles. Although reactions to and ingestion of microplastic are frequently reported, a quantitative comparison to natural particles and of the factors influencing these responses is largely missing. Thus, this study aims to compare the feeding rates of corals to microplastic and natural particles, considering factors influencing these responses. Specifically, we I) studied the feeding responses of corals to microplastic, natural food, and non-food particles, II) examined the influence of biotic factors (i.e., biofilm on the particles and presence of natural food), III) evaluated species-specific differences in feeding responses to microplastic particles, and IV) applied a toxicodynamic model for species- and concentration-dependent risk assessments. We assessed the feeding responses of 11 coral species, spanning different life-history strategies and growth forms in experimental feeding trials. The results showed that the feeding responses of corals to microplastic differ from those to naturally occurring particles. Reactions to microplastic and natural food occurred equally often, while sand was more frequently rejected. Yet, the ingestion process was much more selective, and microplastic was ingested less frequently than natural food. The presence of a biofilm and natural food had activating effects on the feeding behavior of the corals on microplastic. Generally, coral species that exhibit a higher degree of heterotrophic feeding also reacted more often to microplastic. The species- and concentration-dependent toxicodynamic risk model built on these data reveals that most tested coral species are unlikely to be at risk under present environmental concentration levels. However, highly heterotrophic feeders, such as Blastomussa merleti, or generally vulnerable species, such as Pocillopora verrucosa, need special consideration. These findings help to better evaluate the responses of corals to microplastic and their risk in an increasingly polluted ocean.

The trace metal economy of the coral holobiont: supplies, demands and exchanges.

The juxtaposition of highly productive coral reef ecosystems in oligotrophic waters has spurred substantial interest and progress in our understanding of macronutrient uptake, exchange, and recycling among coral holobiont partners (host coral, dinoflagellate endosymbiont, endolithic algae, fungi, viruses, bacterial communities). By contrast, the contribution of trace metals to the physiological performance of the coral holobiont and, in turn, the functional ecology of reef-building corals remains unclear. The coral holobiont's trace metal economy is a network of supply, demand, and exchanges upheld by cross-kingdom symbiotic partnerships. Each partner has unique trace metal requirements that are central to their biochemical functions and the metabolic stability of the holobiont. Organismal homeostasis and the exchanges among partners determine the ability of the coral holobiont to adjust to fluctuating trace metal supplies in heterogeneous reef environments. This review details the requirements for trace metals in core biological processes and describes how metal exchanges among holobiont partners are key to sustaining complex nutritional symbioses in oligotrophic environments. Specifically, we discuss how trace metals contribute to partner compatibility, ability to cope with stress, and thereby to organismal fitness and distribution. Beyond holobiont trace metal cycling, we outline how the dynamic nature of the availability of environmental trace metal supplies can be influenced by a variability of abiotic factors (e.g. temperature, light, pH, etc.). Climate change will have profound consequences on the availability of trace metals and further intensify the myriad stressors that influence coral survival. Lastly, we suggest future research directions necessary for understanding the impacts of trace metals on the coral holobiont symbioses spanning subcellular to organismal levels, which will inform nutrient cycling in coral ecosystems more broadly. Collectively, this cross-scale elucidation of the role of trace metals for the coral holobiont will allow us to improve forecasts of future coral reef function.

Microeconomic adaptation to severe climate disturbances on Australian coral reefs.

Coral reefs are increasingly affected by climate-induced disturbances that are magnified by increasing ocean temperatures. Loss of coral reefs strongly affects people whose livelihoods and wellbeing depend on the ecosystem services reefs provide. Yet the effects of coral loss and the capacity of people and businesses to adapt to it are poorly understood, particularly in the private sector. To address this gap, we surveyed about half (57 of 109) of Australian reef tourism operators to understand how they were affected by and responded to severe impacts from bleaching and cyclones. Reef restoration and spatial diversification were the primary responses to severe bleaching impacts, while for cyclone-impacts coping measures and product diversification were more important. Restoration responses were strongly linked to the severity of impacts. Our findings provide empirical support for the importance of response diversity, spatial heterogeneity, and learning for social-ecological resilience.

The Costs and Benefits of Environmental Memory for Reef-Building Corals Coping with Recurring Marine Heatwaves.

Marine heatwaves are occurring more frequently as climate change intensifies, resulting in global mass coral bleaching events several times per decade. Despite the time between marine heatwaves decreasing, there is evidence that reef-building corals can develop increased bleaching resistance across repetitive marine heatwaves. This phenomenon of acclimatization via environmental memory may be an important strategy to ensure coral persistence; however, we still understand very little about the apparent acclimatization or, conversely, sensitization (i.e., stress accumulation or weakening) of reef-building corals to consecutive heatwaves and its implications for the trajectory and resilience of coral reefs. Here, we highlight that not only will some corals become stress hardened via marine heatwaves, but many other individuals will suffer sensitization during repeat heatwaves that further exacerbates their stress response during repeat events and depresses fitness. Under current and predicted climate change, it is necessary to gain a better understanding of the acclimatization vs. sensitization trajectories of different species and individuals on the reef, as well as identify whether changes in bleaching susceptibility relates to physiological acclimatization, trade-offs with other biological processes, and ultimately coral persistence in the Anthropocene.

A low-cost benthic incubation chamber for in-situ community metabolism measurements.

Benthic incubation chambers facilitate in-situ metabolism studies in shallow water environments. They are used to isolate the water surrounding a study organism or community so that changes in water chemistry can be quantified to characterise physiological processes such as photosynthesis, respiration, and calcification. Such field measurements capture the biological processes taking place within the benthic community while incorporating the influence of environmental variables that are often difficult to recreate in ex-situ settings. Variations in benthic chamber designs have evolved for a range of applications. In this study, we built upon previous designs to create a novel chamber, which is (1) low-cost and assembled without specialised equipment, (2) easily reproducible, (3) minimally invasive, (4) adaptable to varied substrates, and (5) comparable with other available designs in performance. We tested the design in the laboratory and field and found that it achieved the outlined objectives. Using non-specialised materials, we were able to construct the chamber at a low cost (under $20 USD per unit), while maintaining similar performance and reproducibility with that of existing designs. Laboratory and field tests demonstrated minimal leakage (2.08 ± 0.78% water exchange over 4 h) and acceptable light transmission (86.9 ± 1.9%), results comparable to those reported for other chambers. In the field, chambers were deployed in a shallow coastal environment in Akumal, Mexico, to measure productivity of seagrass, and coral-, algae-, and sand-dominated reef patches. In both case studies, production rates aligned with those of comparable benthic chamber deployments in the literature and followed established trends with light, the primary driver of benthic metabolism, indicating robust performance under field conditions. We demonstrate that our low-cost benthic chamber design uses locally accessible and minimal resources, is adaptable for a variety of field settings, and can be used to collect reliable and repeatable benthic metabolism data. This chamber has the potential to broaden accessibility and applications of in-situ incubations for future studies.

Effective asexual reproduction of a widespread soft coral: comparative assessment of four different fragmentation methods.

BACKGROUND: Many coral reefs worldwide are experiencing declines in hard corals, resulting in other benthic organisms, e.g., soft corals, becoming more dominant. As such, more studies on the ecophysiology of soft corals are needed. Despite many methods for asexual reproduction of hard corals, effective methods for soft corals, i.e., without a hard skeleton, are scarce. This study, thus, assessed four fragmentation methods, the glue, rubber band, tunnel mesh, and plug mesh method for the pulsating soft coral Xenia umbellata that is widely distributed in the tropical Indo-Pacific. METHODS: Methods were comparatively assessed by determining the required time and labor for the fragmentation plus the health status of the fragmented corals by measuring their oxygen fluxes and pulsation rates, i.e., a special feature of this soft coral that can be used as a proxy for its health. RESULTS: There were no significant health status differences between methods. This was indicated by similar gross photosynthesis (between 7.4 to 9.7 µg O2 polyp-1 h-1) and pulsating rates (between 35 and 44 pulses min-1) among methods. In terms of time/labor intensity and success rates, i.e., the percentage of fragments attached to the desired surface, the plug mesh method was the most efficient method with a significantly higher success rate (95 ± 5%), while the others had a success rate between 5 ± 5 and 45 ± 15%. The time needed for fragmentation, though not significant, was also the shortest (78 ± 11 s fragment-1), while other methods required between 84 ± 14 and 126 ± 8 s frag-1. The plug mesh method may thus be a valuable tool related to the reproduction of soft corals for use in subsequent experimental work.

Energetic and reproductive costs of coral recovery in divergent bleaching responses.

Mass thermal bleaching events are a primary threat to coral reefs, yet the sublethal impacts, particularly on energetics and reproduction, are poorly characterized. Given that the persistence of coral populations is contingent upon the reproduction of individuals that survive disturbances, there is an urgent need to understand the sublethal effects of bleaching on reproductive output to accurately predict coral recovery rates. In 2019, the French Polynesian island of Mo'orea experienced a severe mass bleaching event accompanied by widespread coral mortality. At the most heavily impacted sites, we observed Acropora hyacinthus individuals that were resistant to bleaching, alongside colonies that bleached but showed signs of symbiont recovery shortly after the bleaching event. We collected fragments from A. hyacinthus colonies five months post-bleaching and, using energetic assays and histological measurements, examined the physiological and reproductive consequences of these two distinct heat stress responses. Despite healthy appearances in both resistant and recovered corals, we found that recovered colonies had significantly reduced energy reserves compared to resistant colonies. In addition, we detected compound effects of stress on reproduction: recovered colonies displayed both a lower probability of containing gametes and lower fecundity per polyp. Our results indicate that bleaching inflicts an energetic constraint on the concurrent re-accumulation of energy reserves and development of reproductive material, with decreased reproductive potential of survivors possibly hampering overall reef resilience. These findings highlight the presence of intraspecific responses to bleaching and the importance of considering multiple trajectories for individual species when predicting population recovery following disturbance.

Species sensitivity assessment of five Atlantic scleractinian coral species to 1-methylnaphthalene.

Coral reefs are keystone coastal ecosystems that are at risk of exposure to petroleum from a range of sources, and are one of the highest valued natural resources for protection in Net Environmental Benefit Analysis (NEBA) in oil spill response. Previous research evaluating dissolved hydrocarbon impacts to corals reflected no clear characterization of sensitivity, representing an important knowledge gap in oil spill preparedness related to the potential impact of oil spills to the coral animal and its photosymbiont zooxanthellae. This research addresses this gap, using a standardized toxicity protocol to evaluate effects of a dissolved reference hydrocarbon on scleractinian corals. The relative sensitivity of five Atlantic scleractinian coral species to hydrocarbon exposure was assessed with 48-h assays using the reference polycyclic aromatic hydrocarbon 1-methylnaphthalene, based on physical coral condition, mortality, and photosynthetic efficiency. The threatened staghorn coral Acropora cervicornis was found to be the most sensitive to 1-methylnaphthalene exposure. Overall, the acute and subacute endpoints indicated that the tested coral species were comparatively more resilient to hydrocarbon exposure than other marine species. These results provide a framework for the prediction of oil spill impacts and impact thresholds on the coral animal and related habitats, essential for informing oil spill response in coastal tropical environments.

In vivo assessment of mitochondrial respiratory alternative oxidase activity and cyclic electron flow around photosystem I on small coral fragments.

The mutualistic relationship existing between scleractinian corals and their photosynthetic endosymbionts involves a complex integration of the metabolic pathways within the holobiont. Respiration and photosynthesis are the most important of these processes and although they have been extensively studied, our understanding of their interactions and regulatory mechanisms is still limited. In this work we performed chlorophyll-a fluorescence, oxygen exchange and time-resolved absorption spectroscopy measurements on small and thin fragments (0.3 cm2) of the coral Stylophora pistillata. We showed that the capacity of mitochondrial alternative oxidase accounted for ca. 25% of total coral respiration, and that the high-light dependent oxygen uptake, commonly present in isolated Symbiodiniaceae, was negligible. The ratio between photosystem I (PSI) and photosystem II (PSII) active centers as well as their respective electron transport rates, indicated that PSI cyclic electron flow occurred in high light in S. pistillata and in some branching and lamellar coral species freshly collected in the field. Altogether, these results show the potential of applying advanced biophysical and spectroscopic methods on small coral fragments to understand the complex mechanisms of coral photosynthesis and respiration and their responses to environmental changes.

The importance of coastal gorgonians in the blue carbon budget.

Terrestrial (trees, shrubs) and marine (seaweeds and seagrasses) organisms act as carbon (C) sinks, but the role of benthic suspension feeders in this regard has been largely neglected so far. Gorgonians are one of the most conspicuous inhabitants of marine animal forests (mainly composed of sessile filter feeders); their seston capture rates influence benthic-pelagic coupling processes and they act as C sinks immobilizing carbon in their long-living structures. Three gorgonian species (Paramuricea clavata, Eunicella singularis and Leptogorgia sarmentosa) were studied coupling data of population size structure, biomass and spatial distribution in a NW Mediterranean area (Cap de Creus, Spain) with feeding, respiration and growth rates. In the study area, we calculated that P. clavata sequestered 0.73 ± 0.71 g C m-2 year-1, E. singularis 0.73 ± 0.89 g C m-2 year-1 and L. sarmentosa 0.03 ± 0.02 g C m-2 year-1. To our knowledge, this is the first attempt to calculate the importance as C sinks of gorgonian species that we consider as a starting point to estimate the importance of marine animal forests in C sequestration, and to ensure appropriate management and protection especially in areas and at depths where they are concentrated.

Development and application of a low-cost rapid assessment system for coastal benthic habitats.

Information on community structure and spatial distribution of benthic habitats are important in marine conservation and management. Coral areas, often monitored by trained scuba divers, are of importance for the ecosystem goods and services they provide. The data gathered may, however, be limited due to cost and time constraints. These restrictions and the continuing decline in coral reef health contribute to the need to develop rapid methods to efficiently document the distribution and status of coral reefs. A Rapid Assessment Instrument for Coastal Benthic Habitats (ARAICoBeH) System was developed to enable large-scale but low-cost coastal benthic habitat characterization and mapping without compromising accuracy. Inquiries on community structure and status in coral-dominated areas are also possible with the data collected using the method. The instrument, as well as the data processing and mapping algorithm are described in detail in this paper. A comparative study was conducted between ARAICoBeH and the frequently used underwater photo transect method. Variables compared were percent coral cover, functional group diversity, community structure as well as time and monetary requirements. There were no significant differences in estimates of percent coral cover and diversity of benthic functional groups for majority of sites while estimates of community structure were very similar. ARAICoBeH is cheaper and requires less time to gather the same amount of data as that of the photo transect method. The spatial distribution of coastal benthic habitats and community structure of coral-dominated areas in El Nido, Palawan, Philippines, are included to illustrate the application of the method.

Drivers of sociality in Gobiodon fishes: An assessment of phylogeny, ecology and life-history.

What drives the evolution of sociality in animals? Many robust studies in terrestrial organisms have pointed toward various kinship-based, ecological and life-history traits or phylogenetic constraint which have played a role in the evolution of sociality. These traits are not mutually exclusive and the exact combination of traits is likely taxon-specific. Phylogenetic comparative analyses have been instrumental in identifying social lineages and comparing various traits with non-social lineages to give broad evolutionary perspectives on the development of sociality. Few studies have attempted this approach in marine vertebrate systems. Social marine fishes are particularly interesting because many have a pelagic larval phase and non-conventional life-history strategies (e.g. bi-directional sex-change) not often observed in terrestrial animals. Such strategies provide novel insights into terrestrially-derived theories of social evolution. Here, we assess the strength of the phylogenetic signal of sociality in the Gobiodon genus with Pagel's lambda and Blomberg's K parameters. We found some evidence of a phylogenetic signal of sociality, but factors other than phylogenetic constraint also have a strong influence on the extant social state of each species. We then use phylogenetic generalized least squares analyses to examine several ecological and life-history traits that may have influenced the evolution of sociality in the genus. We found an interaction of habitat size and fish length was the strongest predictor of sociality. Sociality in larger species was more dependent on coral size than in smaller species, but smaller species were more social overall, regardless of coral size. Finally, we comment on findings regarding the validity of the species G. spilophthalmus which arose during the course of our research. These findings in a group of marine fishes add a unique perspective on the evolution of sociality to the excellent terrestrial work conducted in this field.

Massive corals maintain a positive carbonate budget of a Maldivian upper reef platform despite major bleaching event.

Coral reefs experienced the third global bleaching event in 2015-2016 due to high sea-surface temperature (SST) anomalies. Declines in net carbonate production associated with coral bleaching are implicated in reef structural collapse and cascading impacts for adjacent coral reef islands. We present the first carbonate budget study of a reef platform surface (reef crest and reef flat) in the southern Maldives and the first record of upper reef flat condition in the central Indian Ocean post the 2015-2016 coral bleaching event. Scleractinian corals were the primary carbonate producers, with live coral cover averaging between 11.1 ± 6.5 and 31.2 ± 21.8% and dominated by massive corals. Gross carbonate production rates averaged 5.9 ± 2.5 G (kg CaCO3 m2 yr-1). Bioerosion was estimated at 3.4 ± 0.4 G, resulting in an average net carbonate production rate of 2.5 ± 2.4 G. Comparison of results with a study of the fore-reef slope highlights major differences in post-bleaching carbonate budget state between the fore-reef slope and the reef platform surface. The positive reef flat carbonate budget is attributed to the persistence of massive corals (Porites spp. and Heliopora spp.) through the bleaching event.

Identifying indicators of aesthetics in the Great Barrier Reef for the purposes of management.

The aesthetic appreciation of natural places is one of the most fundamental ways in which people relate to their environment. It provides wellbeing, an opportunity for recreation and reflection, a sense of place, and cultural enrichment. It also motivates people to take care of natural places and to conserve them for current and future appreciation. Aesthetically valuable places also support significant economic activity. However, there is little guidance available to assist environmental managers and policy-makers to consider and integrate aesthetic values into decision-making processes. In this study, we present an approach for developing robust and practical indicators of aesthetic value to enable environmental managers to consider, assess and report on aesthetic condition and trend. We demonstrate its utility using the case of the Great Barrier Reef, a region currently undergoing significant social, economic and environmental change and an area formally protected, in part, for its aesthetic values. A qualitative scoping study with 30 key informants identified over 180 potential qualities contributing to reef aesthetics. We tested five for their utility in capturing key aspects of the coral reef aesthetic: (i) coral cover, (ii) coral pattern, (iii) coral topography, (iv) fish abundance, and (v) visibility. We asked 1,417 online Australians to aesthetically rate 50 out of 181 underwater coral reef images that varied in relation to these five attributes. Coral topography, fish abundance, and visibility were significantly correlated with aesthetic ratings, whilst coral cover and coral pattern were not. We also tested for demographic patterns in aesthetic ratings. Our pilot study has demonstrated that readily measurable characteristics of coral reefs can provide useful indicators of aesthetic quality, opening up opportunities for coral reef managers and policymakers to assess and track changes in aesthetics in ways that are relevant to the public. There is considerable scope to further advance capacity for monitoring and managing aesthetic values of coral reefs through additional research that resolves nuances in the meanings associated with aesthetics in coral reef settings.

What can South African reefs tell us about the future of high-latitude coral systems?

Coral communities are found at high latitude on the East Coast subtropical reefs of South Africa. They are biodiverse, economically important, and afforded World Heritage Site status in the iSimangaliso Wetland Park where some are subjected to recreational use. While the Park's unique coral reefs have, to date, suffered little bleaching from climate change, they are susceptible to the phenomenon and provide a natural laboratory for the study of its effects at high latitude. This review covers recent advances in the regional oceanography; coral community dynamics and the underpinning reef processes, including minor bleaching events; the incidence of coral disease; and coral genetic connectivity. The effects of human activity (SCUBA diving, recreational fishing, pesticide use) were assessed, as well as the nursery benefits of Acropora austera, a coral which provides the reefs with much structure and is vulnerable to damage and climate change. The reefs were valued in terms of human use as well as services such as sediment generation and retention. The results have provided valuable information on relatively pristine, high-latitude reefs, their socio-economic benefits, and the anticipated effects of climate change.

Repeated cyclone events reveal potential causes of sociality in coral-dwelling Gobiodon fishes.

Social organization is a key factor influencing a species' foraging and reproduction, which may ultimately affect their survival and ability to recover from catastrophic disturbance. Severe weather events such as cyclones can have devastating impacts to the physical structure of coral reefs and on the abundance and distribution of its faunal communities. Despite the importance of social organization to a species' survival, relatively little is known about how major disturbances such as tropical cyclones may affect social structures or how different social strategies affect a species' ability to cope with disturbance. We sampled group sizes and coral sizes of group-forming and pair-forming species of the Gobiid genus Gobiodon at Lizard Island, Great Barrier Reef, Australia, before and after two successive category 4 tropical cyclones. Group sizes of group-forming species decreased after each cyclone, but showed signs of recovery four months after the first cyclone. A similar increase in group sizes was not evident in group-forming species after the second cyclone. There was no change in mean pair-forming group size after either cyclone. Coral sizes inhabited by both group- and pair-forming species decreased throughout the study, meaning that group-forming species were forced to occupy smaller corals on average than before cyclone activity. This may reduce their capacity to maintain larger group sizes through multiple processes. We discuss these patterns in light of two non-exclusive hypotheses regarding the drivers of sociality in Gobiodon, suggesting that benefits of philopatry with regards to habitat quality may underpin the formation of social groups in this genus.

The global flood protection savings provided by coral reefs.

Coral reefs can provide significant coastal protection benefits to people and property. Here we show that the annual expected damages from flooding would double, and costs from frequent storms would triple without reefs. For 100-year storm events, flood damages would increase by 91% to $US 272 billion without reefs. The countries with the most to gain from reef management are Indonesia, Philippines, Malaysia, Mexico, and Cuba; annual expected flood savings exceed $400 M for each of these nations. Sea-level rise will increase flood risk, but substantial impacts could happen from reef loss alone without better near-term management. We provide a global, process-based valuation of an ecosystem service across an entire marine biome at (sub)national levels. These spatially explicit benefits inform critical risk and environmental management decisions, and the expected benefits can be directly considered by governments (e.g., national accounts, recovery plans) and businesses (e.g., insurance).

Benefits of biodiverse marine resources to child nutrition in differing developmental contexts in Hispaniola.

There is an urgent need for an improved empirical understanding of the relationship among biodiverse marine resources, human health and development outcomes. Coral reefs are often at this intersection for developing nations in the tropics-an ecosystem targeted for biodiversity conservation and one that provides sustenance and livelihoods for many coastal communities. To explore these relationships, we use the comparative development contexts of Haiti and the Dominican Republic on the island of Hispaniola. We combine child nutrition data from the Demographic Health Survey with coastal proximity and coral reef habitat diversity, and condition to empirically test human benefits of marine natural resources in differing development contexts. Our results indicate that coastal children have a reduced likelihood of severe stunting in Haiti but have increased likelihoods of stunting and reduced dietary diversity in the Dominican Republic. These contrasting results are likely due to the differential in developed infrastructure and market access. Our analyses did not demonstrate an association between more diverse and less degraded coral reefs and better childhood nutrition. The results highlight the complexities of modelling interactions between the health of humans and natural systems, and indicate the next steps needed to support integrated development programming.

Assessment of Cu sub-lethal toxicity (LC50) in the cold-water gorgonian Dentomuricea meteor under a deep-sea mining activity scenario.

Previous aquaria-based experiments have shown dissolution and leaching of metals, especially copper (Cu), from the simulated sediment plumes generated during mining activities resulting in a pronounced increase of Cu contamination in the surrounding seawater. Metals are bioavailable to corals with food, through ingestion (particulate phase) and through tissue-facilitated transport (passive diffusion). With corals being particularly vulnerable to metal contamination, resuspension of metal-bearing sediments during mining activities represents an important ecological threat. This study was undertaken to evaluate the impact of acute copper exposure (LC50;96 h) on the survival of the cold-water octocoral Dentomuricea aff. meteor. The experimental design was divided in two stages. In stage one, a Cu range-finding toxicity test was performed using Cu dilutions in filtered seawater with concentrations of 0 (control); 60; 150; 250; 450; 600 µg/L. Coral mortality was investigated visually based on the percent surface area of tissue changing from natural yellow colour to black colour indicative of tissue necrosis and death. In stage two, we used the results obtained in the range-finding experiment, to define sub-lethal Cu exposure treatments and exposed D. meteor to Cu concentration of 0 (control); 50; 100; 150; 200; 250 µg/L for 96 h. The corals physical conditions were inspected daily and seawater conditions recorded. Corals were considered dead when all of their tissue turned black. The LC50 value was calculated with regression analysis following Probits methodology. Our results indicate that Cu LC50;96 h for the octocoral D. meteor is 137 µg/L.