Coral Reef Ecology Research Articles

The Ecosystem Ecology of Coral Reefs Revisited

Early studies in coral reefs showed that simple measurements of ecosystem metabolism (primary production and ecosystem respiration) were useful for understanding complex reef dynamics at an ecosystem scale. These studies also helped establish the field of ecosystem ecology, but contemporary coral reef ecology has shifted away from these origins. In this manuscript, I describe the historical development of a theory of ecosystem metabolism that was foundational for the discipline of ecosystem ecology, and I update this theory to fully incorporate dynamics on coral reefs (and all ecosystems). I use this updated theory to (a) identify important controls on coral reef processes and (b) provide a rationale for patterns of coral reef carbon dynamics that allow me to generate hypotheses of coral reef ecosystem production. I then use existing data to broadly evaluate these hypotheses. My findings emphasize the importance of integrating measurements of ecosystem metabolism with current approaches to improve the development of theory and the efficacy of conservation and management of coral reefs.

Protection efforts have resulted in ~10% of existing fish biomass on coral reefs

The amount of ocean protected from fishing and other human impacts has often been used as a metric of conservation progress. However, protection efforts have highly variable outcomes that depend on local conditions, which makes it difficult to quantify what coral reef protection efforts to date have actually achieved at a global scale. Here, we develop a predictive model of how local conditions influence conservation outcomes on ~2,600 coral reef sites across 44 ecoregions, which we used to quantify how much more fish biomass there is on coral reefs compared to a modeled scenario with no protection. Under the assumptions of our model, our study reveals that without existing protection efforts there would be ~10% less fish biomass on coral reefs. Thus, we estimate that coral reef protection efforts have led to approximately 1 in every 10 kg of existing fish biomass.

Occurrence of plastic additives in coral-reef invertebrates on natural and plastic substrates

Numerous studies have investigated the occurrence of plastic additives in marine biota. Yet, their main vector of transfer into organisms tissues remains unknown. We explored seven common additives in benthic coral reef invertebrates residing on natural/plastic substrates in a protected marine reserve versus an unprotected reef to ascertain whether additives transfer by substrate leaching. Samples of three coral-reef species were extracted and analyzed by GCMS and HPLC. Of the seven chemical additives investigated, dibenzylamine and bis(2-ethylhexyl) phthalate were detected. No significant association was found between additives and substrate type, possibly because these plastics have been submerged for years, and the majority of additives within them have leached. The marine reserve had fewer samples with additives, highlighting the importance of active management. Understanding the transfer vectors of plastic additives into biota is essential for assessing the risk they pose and devising effective management tools for protecting coral reefs.

Coral reef protection is fundamental to human rights.

The intensifying loss of coral reefs from global climate change and local stressors has seen international commitments targeted at conservation and repair, for example the Kunming-Montreal Global Biodiversity Framework. Fulfilling these targets requires decisions to be made on where, when, and how to act, ultimately dictating where limited resources will be deployed. Every choice on action or inaction toward our ocean has direct and indivisible consequences not only for the health of marine ecosystems but also for the health of humans, particularly those who directly depend on marine habitats, both culturally and economically. The well-being of the environment, humans, and animals is interlinked, co-dependent, and even co-produced, as has already been acknowledged by One Health approaches, which endorse a cross- and trans-disciplinary view to health. Coral reefs epitomie how tightly intertwined ecosystem health and the fate of the human and nonhuman communities that depend on them are. A field that thus far remains poorly considered is a human rights-based approach to coral reef protection. A human rights-based approach implements human rights obligations, including the recently affirmed right to a clean, healthy, and sustainable environment, while embedding principles of accountability, nondiscrimination, participation, and empowerment for local and Indigenous communities that ensure effectiveness and meaningful stakeholder engagement. Tying the protection of coral reef ecosystems to human rights emphasises the importance of healthy ecosystems to human well-being and thus the inevitable connection between nonhuman and human life. The general failure to consider coral reef protection through a human rights-based approach is a missed opportunity to expedite reef protection while simultaneously advancing climate justice for both humans and nonhumans.

Biological control of ultra-skeleton mineralization in coral

Abstract Understanding the mineralization of coral is significant for the formation of coral reefs and paleoclimatic reconstructions. However, the fundamental mechanisms involved in biomineralization are poorly understood. A combination of Raman spectral and cross-polarized reflected light microscopy imaging was used to examine the three-dimensional spatial distribution of the skeletal ultrastructures and their associated mineral, organic, and water chemistry in coral, which enable insight into the spatial growth features of the ultrastructures and possible formation processes. A possible mechanism is proposed that controls the formation of skeletal ultrastructures, which likely involves compartmentalized calcifying cells and their related cellular activities. This could clarify the association between coral skeletal mineralization and biology, and it may be beneficial to better protection and application of coral reefs.

Long-term exposure to climbazole may affect the health of stress-tolerant coral Galaxea fascicularis

The persistence of coral reefs globally is threatened by various forms of chemical pollution. Climbazole, an azole antibacterial agent extensively utilized in pharmaceuticals and personal care products (PPCPs) in everyday life, has been detected in various environment media and proved to have significant adverse effects on aquatic organism. However, the effects of climbazole on coral remain largely unknown. Therefore, in this study, we conducted a 42-day investigation to examine the effects of varying concentrations of climbazole on Galaxea fascicularis (G. fascicularis), a stress-tolerant coral species. Our investigations included coral color observations, physiological experiments, and assessments of microbial diversity. The results showed that, after 42 days of exposure, the coral color in the treatment group exposed to 100 μg/L climbazole significantly decreased by one color category on the reference chart (D6 shifted to D5), while there was no change in the control group. This was accompanied by an increase in oxidative stress and a decrease in photosynthetic capacity in coral specimens. Additionally, there was a notable alteration in microbial diversity, resulting in reduced community stability. Elevated levels of climbazole (100 μg/L) stress led to an increased abundance of potentially pathogenic bacteria such as unclassified Erysipelotrichaceae. However, at an environmentally relevant concentration of 1 μg/L, climbazole decreased the photosynthetic efficiency and induced oxidative stress in the stress-tolerant coral G. fascicularis, while not significantly impacting the microbial community diversity of the coral. The findings of our study have important implications for the protection and management of nearshore coral reefs and offer essential data for ecological risk assessment of climbazole.

Cumulative risk of future bleaching for the world's coral reefs.

Spatial and temporal patterns of future coral bleaching are uncertain, hampering global conservation efforts to protect coral reefs against climate change. Our analysis of daily projections of ocean warming establishes the severity, annual duration, and onset of severe bleaching risk for global coral reefs this century, pinpointing vital climatic refugia. We show that low-latitude coral regions are most vulnerable to thermal stress and will experience little reprieve from climate mitigation. By 2080, coral bleaching is likely to start on most reefs in spring, rather than late summer, with year-round bleaching risk anticipated to be high for some low-latitude reefs regardless of global efforts to mitigate harmful greenhouse gasses. By identifying Earth's reef regions that are at lowest risk of accelerated bleaching, our results will prioritize efforts to limit future loss of coral reef biodiversity.

Coral Safe or Skin Safe?: Risk Information Behaviors and Green Purchase Decisions

Coral bleaching threatens coral safety and the marine environment. Coral-safe sunscreens are encouraged as a green product to protect coral reefs by many U.S. states and other nations. This study cited key variables from the planned risk information seeking and processing (PRISM) model to explore the connection between risk information behaviors and pro-environmental purchase decisions. We surveyed a sample of 409 U.S. respondents, and employed structural equation modeling for analysis. Results showed that both information seeking and processing were precursors to consumers’ product information seeking during purchasing, thereby impacting the purchase intent of coral-safe sunscreens. Systematic processing is also directly related to the purchase intent. Implications are further discussed.

Evidence for the production of asexual resting cysts in a free-living species of Symbiodiniaceae (Dinophyceae)

Coral reef ecosystems are the most productive and biodiverse marine ecosystems, with their productivity levels highly dependent on the symbiotic dinoflagellates belonging to the family Symbiodiniaceae. As a unique life history strategy, resting cyst production is of great significance in the ecology of many dinoflagellate species, those HABs-causing species in particular, however, there has been no confirmative evidence for the resting cyst production in any species of the family Symbiodiniaceae. Based on morphological and life history observations of cultures in the laboratory and morpho-molecular detections of cysts from the marine sediments via fluorescence in situ hybridization (FISH), cyst photography, and subsequent singe-cyst PCR sequencing, here we provide evidences for the asexual production of resting cysts by Effrenium voratum, the free-living, red tide-forming, and the type species of the genus Effrenium in Symbiodiniaceae. The evidences from the marine sediments were obtained through a sequential detections: Firstly, E. voratum amplicon sequence variants (ASVs) were detected in the cyst assemblages that were concentrated with the sodium polytungstate (SPT) method from the sediments collected from different regions of China Seas by high-throughput next generation sequencing (NGS); Secondly, the presence of E. voratum in the sediments was detected by PCR using the species-specific primers for the DNA directly extracted from sediment; Thirdly, E. voratum cysts were confirmed by a combined approach of FISH using the species-specific probes, light microscopic (LM) photography of the FISH-positive cysts, and a subsequent single-cyst PCR sequencing for the FISH-positive and photographed cysts. The evidences from the laboratory-reared clonal cultures of E. voratum include that: 1) numerous cysts formed in the two clonal cultures and exhibited a spherical shape, a smooth surface, absence of ornaments, and a large red accumulation body; 2) cysts could maintain morphologically intact for a storage of two weeks to six months at 4 °C in darkness and of which 76–92 % successfully germinated through an internal development processes within a time period of 3–21 days after being transferred back to the normal culturing conditions; 3) two or four germlings were released from each cyst through the cryptopylic archeopyle in all cysts with continuous observations of germination processes; and 4) while neither sexual mating of gametes nor planozygote (cells with two longitudinal flagella) were observed, the haploidy of cysts was proven with flow cytometric measurements and direct LM measurements of fluorescence from cells stained with either propidium iodide (PI) or DAPI, which together suggest that the cysts were formed asexually. All evidences led to a conclusion that E. voratum is capable of producing asexual resting cysts, although its sexuality cannot be completely excluded, which guarantees a more intensive investigation. This work fills a gap in the knowledge about the life cycle, particularly the potential of resting cyst formation, of the species in Symbiodiniaceae, a group of dinoflagellates having unique life forms and vital significance in the ecology of coral reefs, and may provide novel insights into understanding the recovery mechanisms of coral reefs destructed by the global climate change and suggest various forms of resting cysts in the cyst assemblages of dinoflagellates observed in the field sediments, including HABs-causing species.

Coral-reef ecology: Expanding urchin disease threatens ecosystem balance

Sea urchins are critically important herbivores on coral reefs. A new study shows that a disease that decimated sea urchins in the Caribbean in 2022 has spread to the Red Sea, further threatening coral ecosystems.

Synthesizing the Ecological and Societal Ramifications of Environmental Stressors on Philippine Marine Ecosystems: A Comprehensive Literature Review

Coral reefs, which serve as essential ecosystems that support marine biodiversity and coastal populations, are declining at an alarming rate worldwide, including in the Philippines. This study explores the specific effects of overfishing, the causes, and effects of pollution on Philippine waters to understand better rising sea levels, ocean acidification, the overall impact of climate change on coral reefs, and the value of these coral habitats to local communities. Data were acquired using a qualitative approach through literature reviews of secondary sources. The findings show that overfishing, pollution, climate change, and habitat destruction are major causes of coral reef decline in the Philippines. These factors have resulted in severe reductions in coral cover, biodiversity loss, and decreased ecosystem services. Furthermore, coral reef decline has far-reaching consequences for Philippine biodiversity, including decreased resistance to environmental stressors and greater vulnerability of coastal people. This study highlights the urgency for coordinated conservation initiatives, such as enhanced management tactics, sustainable fishing practices, and climate change mitigation measures. Recommendations include creating marine protected areas, stronger coastal development rules, and public awareness programs to support coral reef protection. Addressing coral reef loss is crucial for protecting Philippine biodiversity and ensuring the long-term viability of marine ecosystems.

Rehabilitating coral reefs in the Anthropocene

Coral reefs provide food and livelihoods for hundreds of millions of coastal people in over 100 countries. Recent global estimates for the total value of goods and services that they can generate indicate around US$ 105,000-350,000 per hectare per year, but local estimates of current total economic value can be one to two orders of magnitude lower. Unfortunately, coral reefs are under threat both from local human stressors (for example, sediment and nutrient run-off from agriculture, sewage discharges, dredging, destructive fishing, land 'reclamation', overfishing) and, increasingly, from stressors related to global climate change (not only El Niño Southern Oscillation-related marine heatwaves, which cause mass bleaching and mortality of corals, but also more frequent and powerful tropical cyclones and ocean acidification). Four successive mass-bleaching events on Australia's iconic Great Barrier Reef between 2016 and 2022 (plus another one currently underway) have focused world attention on the need for urgent action to protect coral reefs. It is clear that coral reef ecosystems will continue to decline unless anthropogenic greenhouse gas emissions are reduced and innovative management strategies are developed to assist adaptation.

Reduce pollution, establish protected areas, manage fisheries properly? How to protect coral reefs based on carbon trading

As coral reefs around the world have suffered serious damage, it is necessary to protect them. Common modes of coral reef protection include reducing pollution, setting up reserves and managing fisheries rationally. In order to derive the applicable scope of various protection modes for coral reefs, this article constructs three differential game models and compares and analyzes the equilibrium results obtained by the models. Finally, the study shows that whether for developed or developing countries, when the benefits of coral reef treatment are small, the mode of reducing pollution can achieve the maximum benefit. As the benefits of coral reef treatment gradually increase, the mode of setting up nature reserves can achieve the maximum benefit. It is worth noting that the greater the carbon emission rights obtained by the number of coral reefs, the greater the benefits of coral reef treatment, the more likely developed countries will adopt the mode of setting up reserves.

Laboratory Investigation of Energy Dissipation and Turbulent Mixing During Internal Solitary Wave Breaking on the Rough Shelf Slope

AbstractWhen internal solitary waves (ISW) propagate to the continental shelf, they typically runup and break on the forereef. This process might lead to periodic temperature drops at the reef slope, which has potential to protect coral reefs from bleaching threats. A series of laboratory experiments were conducted to investigate turbulence characteristics and energy dissipation during the ISW breaking events on the shelf slope with different bottom roughness to mimic the forereef environment. Particle image velocimetry (PIV) and planar laser‐induced fluorescence (PLIF) were coupled to obtain simultaneous high‐resolution velocity and density fields, based on which we then calculate the energy budget and turbulent dissipation rate. We found that the ISW breaking can be divided into two turbulent processes, the production of shear instability and coherent structures. Ratio of energy loss is weakened with the increase of bottom roughness and the collapse height, while the rough structure substantially enhanced the turbulent dissipation rate. The mixing efficiency is between 0.1 and 0.3, close to its maximal rate at 0.25. Our results reveal that the bottom roughness has impact on the mixing efficiency and turbulent process during the ISW breaking events. We found that rough structures at the shelf slope inhibit the mixing efficiency, especially in cases with small amplitude incline ISW. This finding may help us to better understand the reef damage and coral reef decline and support the management of coral protection strategy.

Environmental Concentrations of Herbicide Prometryn Render Stress-Tolerant Corals Susceptible to Ocean Warming.

Global warming has caused the degradation of coral reefs around the world. While stress-tolerant corals have demonstrated the ability to acclimatize to ocean warming, it remains unclear whether they can sustain their thermal resilience when superimposed with other coastal environmental stressors. We report the combined impacts of a photosystem II (PSII) herbicide, prometryn, and ocean warming on the stress-tolerant coral Galaxea fascicularis through physiological and omics analyses. The results demonstrate that the heat-stress-induced inhibition of photosynthetic efficiency in G. fascicularis is exacerbated in the presence of prometryn. Transcriptomics and metabolomics analyses indicate that the prometryn exposure may overwhelm the photosystem repair mechanism in stress-tolerant corals, thereby compromising their capacity for thermal acclimation. Moreover, prometryn might amplify the adverse effects of heat stress on key energy and nutrient metabolism pathways and induce a stronger response to oxidative stress in stress-tolerant corals. The findings indicate that the presence of prometryn at environmentally relevant concentrations would render corals more susceptible to heat stress and exacerbate the breakdown of coral Symbiodiniaceae symbiosis. The present study provides valuable insights into the necessity of prioritizing PSII herbicide pollution reduction in coral reef protection efforts while mitigating the effects of climate change.

Exploring benthic habitat assessments on coral reefs: a comparison of direct field measurements versus remote sensing

Coral reefs are spatially variable ecosystems that form biogenic structures ranging in size from 10 to 1000s of meters. Their changes in response to anthropogenic stress are occurring across increasingly broad scales, yet our ability to detect, understand and respond to these changes at relevant scales is limited. Traditional in-water observation-based coral reef ecology and remote sensing-based methods both offer valuable insights into benthic change, but their relative scalability and use to-date must be understood to inform optimal future research approaches. We conducted a systematic literature review comparing the approaches used to quantify benthic habitat, through traditional in-water ecological studies and remote sensing studies, with respect to: (a) their geographic distribution, (b) reef zone selection, and c) their focal questions. Among the 199 studies reviewed, traditional ecological studies primarily concentrated on community composition (89%), using high-detail direct measurements, especially from the reef slope (80%). By contrast, remote sensing studies provided spatially explicit datasets at coarser spatial and thematic resolutions, with a predominant focus on benthic mapping (72%) across entire reef systems. Only 3% of studies integrated both approaches, combining comprehensive in-situ observations with broadscale remote sensing. As anthropogenic stressors continue to increase in scale, bridging these scientific disciplines offers a promising way to upscale observations to entire reef-scape scales. We identify steps to harness the strengths of both fields and integrate multiple tools at various levels of resolution and scale. Such bridging approaches offer a way forward in understanding and managing coral reef functioning in the Anthropocene.

First observations of coral spawning at the Banda Islands, Maluku, Indonesia

Abstract. Novriansyah A, Huhn M, Wicaksono H, Senen B, Subhan B, Fenner D, Madduooa H, Dias PJ. 2023. First observations of coral spawning at the Banda Islands, Maluku, Indonesia. Biodiversitas 24: 6082-6091. Due to their high diversity and productivity, their socio-economic value to coastal communities and their crucial role in coastal protection, coral reefs belong to the most important marine ecosystems in the world. Understanding and protecting coral reefs has never been so important, given the unprecedented anthropogenic pressures they face. Indonesia holds 18% of the world’s coral reefs and is home to some of the richest marine biodiversity on the planet. However, with over 17,000 islands scattered across 86,700 km2, marine monitoring and conservation remains challenging. The Banda Sea (Maluku, Indonesia) ecoregion ranks as a high priority for marine conservation. The present study reports on the first observations of coral spawning at the Banda Islands from 2016 to 2019. Ad-hoc opportunistic monitoring was carried out to identify patterns of coral spawning. Our results suggest the sharpest temperature increases and full moon timing have the biggest influence on the month and day of coral spawning, whereas the tidal cycle influences the hour when gametes are released. Coral spawning peaks were observed to occur in two seasons, April and October-November, 5-7 days after full moon and 2-3 hours after sunset during falling tides. The presence of two spawning seasons may provide coral reefs at the Banda Islands with an advantage to recover from potential impacts, such as storms, bleaching or destructive fishing.

Close-range underwater photogrammetry for coral reef ecology: a systematic literature review

Close-range underwater photogrammetry for coral reef ecology: a systematic literature review

Marine protected areas are a useful tool to protect coral reef fishes but not representative to conserve their functional role

Anthropogenic actions have direct and indirect impacts on natural systems, leading to significant alterations in marine ecosystems worldwide. One of the most notable problems is species loss, as the disappearance of species from an area can compromise ecological functions. This is at the core of a severe biodiversity crisis. To address and reverse these processes, marine protected areas (MPAs) have been utilized as a crucial tool to mitigate species loss, increase biomass, and serve as a fisheries management tool. However, there is a lack of information assessing MPAs from the perspective of their contribution to maintaining ecological functions. In recent decades, functional diversity (FD) indices have been widely used to assess ecosystem functioning. In this paper, we conducted an assessment using a global database of reef fish abundance to analyze the effect of No-Take Zones (NTZ) on the FD and “true” diversity (TD) indices of tropical reef fish assemblages in seven tropical biogeographic regions. We found a significant protective effect for some indices, although these responses were dependent on the bioregion. At the bioregional level, NTZs included lower numbers of species and functional entities than open access areas. Consequently, the functional richness protected within these zones partially represented the functional diversity in each biogeographic province. However, smaller-scale functional diversity indices responded to NTZ protection depending on the bioregion. Therefore, these results reinforce that the assessed NTZs are responsive to the protection of functional diversity, although they are not sufficient for safeguarding ecosystem functions in tropical reefs. This highlights the importance of expanding the number of protection entities worldwide with management strategies focused on coral reef fish functionality, as well as effective local/regional assessments. Thus, a new paradigm is necessary in the planning and creation of MPAs to safeguard ecosystem functions, with a priority given to the protection of ecosystem functions and habitats.

Impact of Ocean Acidification on Coral Reefs and the Marine Ecosystems in Phillipines

Purpose: The aim of the study was to investigate the impact of ocean acidification on coral reefs and the marine ecosystems in phillipines
 Methodology: The study adopted a desktop methodology. Desk research refers to secondary data or that which can be collected without fieldwork. Desk research is basically involved in collecting data from existing resources hence it is often considered a low cost technique as compared to field research, as the main cost is involved in executive’s time, telephone charges and directories. Thus, the study relied on already published studies, reports and statistics. This secondary data was easily accessed through the online journals and library
 Findings: Ocean acidification reduces the density and growth of coral skeletons, making them more vulnerable to erosion. This threatens coral reefs and the marine life that depends on them. It also affects human benefits from coral reefs, such as fisheries, tourism and storm protection.
 Unique Contribution to Theory, Practice and Policy: Theory of Ocean Acidification and Coral Calcification, Theory of Ocean Acidification and Biodiversity Loss and Theory of Adaptation and Resilience of Coral Reefs may be used to anchor future studies on impact of ocean acidification on coral reefs and the marine ecosystems in Philippines. Philippine government should actively participate in global climate agreements and implement policies to reduce carbon emissions at the domestic level. The Philippine government should integrate ocean acidification considerations into national environmental policies and action plans, such as the Philippine Coral Reef Protection Program.