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Biodiversity of coral reefs
\"Discusses the variety of living things in a coral reef's ecosystem\"--Provided by publisher.
Book
Coral reef spawning
Coral reefs regenerate themselves. Some corals are hermaphroditic, releasing packages of eggs and sperm. Somehow, it works out that dozens of different species release eggs and sperm at the same time. They float together and begin fertilization, creating larvae. The larvae then settles, and morphs into a polyp. The polyps secrete a hard skeleton of limestone. Slowly and gradually, a huge coral reef is formed. They are the largest structures built by living creatures in the world, and take millions of years to build. But it only takes a little time for careless divers, boaters, and global warming to destroy huge parts of them. Not only is this a problem for the coral, but also a quarter of all sea creatures call the reefs home.
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Microbial disease causation in marine invertebrates: problems, practices, and future prospects
Diseases of marine organisms appear to be increasing world-wide, but the causes of many of these remain a mystery. Here we outline steps that we have taken to identify various pathogens of marine invertebrates. These methods, however, rely on the successful cultivation of marine pathogens in the laboratory. Although Koch's postulates were established to generate evidence that a microorganism is the cause of an infectious disease, the limitations of these postulates in detecting microbes that are resistant to cultivation renders the sole use of them impossible in some situations. We, therefore, discuss some sensitive and comprehensive methods for detecting human-associated pathogens that can be adapted and applied to marine systems. A set of nucleic acid sequence-based approaches for establishing microbial disease causation in marine invertebrates is outlined that can be used in collaboration with traditional culture-based and histopathological methods to build a compelling case for microbial disease causation. In addition to providing potential evidence of causation, these same methods can add greatly to the current database of knowledge dealing with marine microbial communities and will ultimately enhance our understanding of emerging diseases in marine systems.[PUBLICATION ABSTRACT]
Journal Article
Ecosystem restructuring along the Great Barrier Reef following mass coral bleaching
Global warming is markedly changing diverse coral reef ecosystems through an increasing frequency and magnitude of mass bleaching events
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–
3
. How local impacts scale up across affected regions depends on numerous factors, including patchiness in coral mortality, metabolic effects of extreme temperatures on populations of reef-dwelling species
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and interactions between taxa. Here we use data from before and after the 2016 mass bleaching event to evaluate ecological changes in corals, algae, fishes and mobile invertebrates at 186 sites along the full latitudinal span of the Great Barrier Reef and western Coral Sea. One year after the bleaching event, reductions in live coral cover of up to 51% were observed on surveyed reefs that experienced extreme temperatures; however, regional patterns of coral mortality were patchy. Consistent declines in coral-feeding fishes were evident at the most heavily affected reefs, whereas few other short-term responses of reef fishes and invertebrates could be attributed directly to changes in coral cover. Nevertheless, substantial region-wide ecological changes occurred that were mostly independent of coral loss, and instead appeared to be linked directly to sea temperatures. Community-wide trophic restructuring was evident, with weakening of strong pre-existing latitudinal gradients in the diversity of fishes, invertebrates and their functional groups. In particular, fishes that scrape algae from reef surfaces, which are considered to be important for recovery after bleaching
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, declined on northern reefs, whereas other herbivorous groups increased on southern reefs. The full impact of the 2016 bleaching event may not be realized until dead corals erode during the next decade
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,
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. However, our short-term observations suggest that the recovery processes, and the ultimate scale of impact, are affected by functional changes in communities, which in turn depend on the thermal affinities of local reef-associated fauna. Such changes will vary geographically, and may be particularly acute at locations where many fishes and invertebrates are close to their thermal distribution limits
7
.
Fish and invertebrate communities transformed across the span of the Great Barrier Reef following the 2016 bleaching event due to a decline in coral-feeding fishes resulting from coral loss, and because of different regional responses of key trophic groups to the direct effect of temperature.
Journal Article
Coral cover a stronger driver of reef fish trophic biomass than fishing
An influential paradigm in coral reef ecology is that fishing causes trophic cascades through reef fish assemblages, resulting in reduced herbivory and thus benthic phase shifts from coral to algal dominance. Few long-term field tests exist of how fishing affects the trophic structure of coral reef fish assemblages, and how such changes affect the benthos. Alternatively, benthic change itself may drive the trophic structure of reef fish assemblages. Reef fish trophic structure and benthic cover were quantified almost annually from 1983 to 2014 at two small Philippine islands (Apo, Sumilon). At each island a No-Take Marine Reserve (NTMR) site and a site open to subsistence reef fishing were monitored. Thirteen trophic groups were identified. Large planktivores often accounted for >50% of assemblage biomass. Significant NTMR effects were detected at each island for total fish biomass, but for only 2 of 13 trophic components: generalist large predators and large planktivores. Fishing-induced changes in biomass of these components had no effect on live hard coral (HC) cover. In contrast, HC cover affected biomass of 11 of 13 trophic components significantly. Positive associations with HC cover were detected for total fish biomass, generalist large predators, piscivores, obligate coral feeders, large planktivores, and small planktivores. Negative associations with HC cover were detected for large benthic foragers, detritivores, excavators, scrapers, and sand feeders. These associations of fish biomass to HC cover were most clear when environmental disturbances (e.g., coral bleaching, typhoons) reduced HC cover, often quickly (1–2 yr), and when HC recovered, often slowly (5–10 yr). As HC cover changed, the biomass of 11 trophic components of the fish assemblage changed. Benthic and fish assemblages were distinct at all sites from the outset, remaining so for 31 yr, despite differences in fishing pressure and disturbance history. HC cover alone explained ~30% of the variability in reef fish trophic structure, whereas fishing alone explained 24%. Furthermore, HC cover affected more trophic groups more strongly than fishing. Management of coral reefs must include measures to maintain coral reef habitats, not just measures to reduce fishing by NTMRs.
Journal Article
The Tara Pacific expedition—A pan-ecosystemic approach of the “-omics” complexity of coral reef holobionts across the Pacific Ocean
Coral reefs are the most diverse habitats in the marine realm. Their productivity, structural complexity, and biodiversity critically depend on ecosystem services provided by corals that are threatened because of climate change effects-in particular, ocean warming and acidification. The coral holobiont is composed of the coral animal host, endosymbiotic dinoflagellates, associated viruses, bacteria, and other microeukaryotes. In particular, the mandatory photosymbiosis with microalgae of the family Symbiodiniaceae and its consequences on the evolution, physiology, and stress resilience of the coral holobiont have yet to be fully elucidated. The functioning of the holobiont as a whole is largely unknown, although bacteria and viruses are presumed to play roles in metabolic interactions, immunity, and stress tolerance. In the context of climate change and anthropogenic threats on coral reef ecosystems, the Tara Pacific project aims to provide a baseline of the \"-omics\" complexity of the coral holobiont and its ecosystem across the Pacific Ocean and for various oceanographically distinct defined areas. Inspired by the previous Tara Oceans expeditions, the Tara Pacific expedition (2016-2018) has applied a pan-ecosystemic approach on coral reefs throughout the Pacific Ocean, drawing an east-west transect from Panama to Papua New Guinea and a south-north transect from Australia to Japan, sampling corals throughout 32 island systems with local replicates. Tara Pacific has developed and applied state-of-the-art technologies in very-high-throughput genetic sequencing and molecular analysis to reveal the entire microbial and chemical diversity as well as functional traits associated with coral holobionts, together with various measures on environmental forcing. This ambitious project aims at revealing a massive amount of novel biodiversity, shedding light on the complex links between genomes, transcriptomes, metabolomes, organisms, and ecosystem functions in coral reefs and providing a reference of the biological state of modern coral reefs in the Anthropocene.
Journal Article
Coral reef restoration in Indonesia: lessons learnt from the world’s largest coral restoration nation
Indonesia is the global coral reef restoration leader by number of projects, yet these remain diverse and disparate. This study reviews the status of Indonesian coral reef restoration within a framework of international common best practice (CBP) that incorporates internationally-recognised Standards for Ecological Restoration (SER). This framework is used to formulate recommendations for a formal network of reef restoration practitioners with the purview to develop and implement a national restoration roadmap. Forty-five projects were surveyed to determine how projects have been planned and implemented. This was compared with recommendations from CBP. There is particular scope to increase quantitative data collection, reinforce community involvement, improve ecological data collection, and standardise monitoring protocols. While 84% of projects reported quantifiable goals, 64% did not quantify goals during planning and 61% did not incorporate climate-smart design features. Quantitative reef monitoring surveys were absent in 22% of projects. The majority of projects did not quantify important ecological metrics like coral community composition/diversity (96%), coral health/bleaching (89%), benthic community (62%), and coral survival (62%). Indonesia has the capacity, regulations, and networks to position itself as a reef restoration driver in the Coral Triangle region; this will require increased coordination, alignment, and quantification of restoration. A structured, collaborative, and iterative national network of various stakeholders would facilitate the development of a national restoration roadmap based on adaptive management strategies. This would aid in standardising project planning, monitoring, and reporting. Efforts should include an increased focus on climate change adaptation goals.
Journal Article
Microbial indicators of environmental perturbations in coral reef ecosystems
Background
Coral reefs are facing unprecedented pressure on local and global scales. Sensitive and rapid markers for ecosystem stress are urgently needed to underpin effective management and restoration strategies. Although the fundamental contribution of microbes to the stability and functioning of coral reefs is widely recognised, it remains unclear how different reef microbiomes respond to environmental perturbations and whether microbiomes are sensitive enough to predict environmental anomalies that can lead to ecosystem stress. However, the lack of coral reef microbial baselines hinders our ability to study the link between shifts in microbiomes and ecosystem stress. In this study, we established a comprehensive microbial reference database for selected Great Barrier Reef sites to assess the diagnostic value of multiple free-living and host-associated reef microbiomes to infer the environmental state of coral reef ecosystems.
Results
A comprehensive microbial reference database, originating from multiple coral reef microbiomes (i.e. seawater, sediment, corals, sponges and macroalgae), was generated by 16S rRNA gene sequencing for 381 samples collected over the course of 16 months. By coupling this database to environmental parameters, we showed that the seawater microbiome has the greatest diagnostic value to infer shifts in the surrounding reef environment. In fact, 56% of the observed compositional variation in the microbiome was explained by environmental parameters, and temporal successions in the seawater microbiome were characterised by uniform community assembly patterns. Host-associated microbiomes, in contrast, were five-times less responsive to the environment and their community assembly patterns were generally less uniform. By applying a suite of indicator value and machine learning approaches, we further showed that seawater microbial community data provide an accurate prediction of temperature and eutrophication state (i.e. chlorophyll concentration and turbidity).
Conclusion
Our results reveal that free-living microbial communities have a high potential to infer environmental parameters due to their environmental sensitivity and predictability. This highlights the diagnostic value of microorganisms and illustrates how long-term coral reef monitoring initiatives could be enhanced by incorporating assessments of microbial communities in seawater. We therefore recommend timely integration of microbial sampling into current coral reef monitoring initiatives.
Journal Article
Toxic effects of UV filters from sunscreens on coral reefs revisited: regulatory aspects for “reef safe” products
BackgroundTropical coral reefs have been recognized for their significant ecological and economical value. However, increasing anthropogenic disturbances have led to progressively declining coral reef ecosystems on a global scale. More recently, several studies implicated UV filters used in sunscreen products to negatively affect corals and possibly contribute to regional trends in coral decline. Following a public debate, bans were implemented on several organic UV filters and sunscreen products in different locations including Hawaii, the U.S. Virgin Islands and Palau. This included banning the widely used oxybenzone and octinoxate, while promoting the use of inorganic filters such as zinc oxide even although their toxicity towards aquatic organisms had been documented previously. The bans of organic UV filters were based on preliminary scientific studies that showed several weaknesses as there is to this point no standardized testing scheme for scleractinian corals. Despite the lack of sound scientific proof, the latter controversial bans have already resulted in the emergence of a new sunscreen market for products claimed to be ‘reef safe’ (or similar). Thus, a market analysis of ‘reef safe’ sunscreen products was conducted to assess relevant environmental safety aspects of approved UV filters, especially for coral reefs. Further, a scientifically sound decision-making process in a regulatory context is proposed.ResultsOur market analysis revealed that about 80% of surveyed sunscreens contained inorganic UV filters and that there is a variety of unregulated claims being used in the marketing of ‘reef safe’ products with ‘reef friendly’ being the most frequently used term. Predominantly, four organic UV filters are used in ‘reef safe’ sunscreens in the absence of the banned filters oxybenzone and octinoxate. Analysis of safe threshold concentrations for marine water retrieved from existing REACH registration dossiers could currently also safeguard corals.ConclusionThere is a substantial discrepancy of treatments of organic versus inorganic UV filters in politics as well as in the ‘reef safe’ sunscreen market, which to this point is not scientifically justified. Thus, a risk-based approach with equal consideration of organic and inorganic UV filters is recommended for future regulatory measures as well as a clear definition and regulation of the ‘reef safe’ terminology.
Journal Article
Coral microbiome dynamics, functions and design in a changing world
Corals associate not only with dinoflagellates, which are their algal endosymbionts and which have been extensively studied over the past four decades, but also with a variety of other microorganisms. The coral microbiome includes dinoflagellates, viruses, fungi, archaea and bacteria, with knowledge of the latter growing rapidly. This Review focuses on the bacterial members of the coral microbiome and draws parallels with better-studied microbiomes in other biological systems. We synthesize current understanding of spatial, temporal and host-specific patterns in coral-associated bacterial communities, the drivers shaping these patterns, and the role of the microbiome in acclimatization and adaptation of the host to climate warming. We discuss how this knowledge can be harnessed to assist the future persistence of coral reefs and provide novel perspectives for the development of microbiome engineering and its implications for coral reef conservation and restoration.
Journal Article