Coral Disease Research Articles

Parasitic pathways and evaluation of non-specific parasitism of ciliate infected captive corals

Coral disease is a serious challenge for thesurvival of both wild and farmed corals. Ciliate infection causes severe damage on the coral health. The present study is the first report on the non-specific infection potential of ciliate parasites on four kinds of corals. The ciliates were isolated from an infected coral, Euphyllia glabrescens and re-infected to various coral species (Acropora muricata, Goniopora columna, Lemnalia fiava, Heteroxenia pinnata). This study aims to bring insights on ciliate infection rate, specific characteristics of infections, and infection pathway of ciliate in corals. In addition, the study also assessed the nature of parasitization in multiple corals, which could be helpful for a significant risk assessment on large-scale coral aquaculture. The 18S rRNA ciliate gene identification results showed about 99% sequence similarity with the Philaster lucinda found in Acropora coral. The purified ciliate was fed with 5 × 106 cell mL−1 of zooxanthellae and could achieve good proliferation. The specific growth rate of the ciliates was increased after 18 h of infection in the E. glabrescens, reaching 828.33 ± 26.10 cell mL−1. Subsequently, the atrophy of coral polyps was observed after 12 h. After 24 h of infection, the coral began to die as the amount/number of zooxanthellae and chlorophyll a were significantly decreased. The coral suffered with 100% mortality within 72 h of infection. The histological study revealed that ciliate parasitized to coral's endoderm while entering the coral coelenteron via its mouth. Tests of ciliate infection revealed that four types of cultured corals were infected by this ciliate and rapidly rot and die, which suggests its non-specific parasitism potential. Furthermore, this study confirmed their onset of infection on different corals simultaneously, which is an important aspect for future coral research, ensuring coral disease management and designing drugs for ciliate prevention.

Prevalence and extent of coral diseases in shallow and mesophotic reefs of the Southwestern Atlantic

Coral reef ecology has advanced in many fields, but disease patterns across depth gradients remain unclear. By comparing the prevalence and extent of bleaching and diseases in 160 colonies of Siderastrea stellata between shallow and mesophotic reefs, we observed that prevalence was high (75%) regardless of depth, but the extent was about two times greater in mesophotic than shallow reefs (14.4% vs. 6.6% of colony area, respectively). Across the shallow reefs, where S. stellata co-occurred with Montastraea cavernosa, M. cavernosa showed lower prevalence (27% of 30 colonies) and extent (1.8% of colony area) compared to S. stellata. Besides bleaching, five coral diseases afflicted S. stellata and two affected M. cavernosa. Because diseases are spread over the entire gradient of depth, any attempt of managing the diseases should consider both shallow and deep reefs to be effective.

The past, present, and future of coral reef growth in the Florida Keys.

Coral‐reef degradation is driving global‐scale reductions in reef‐building capacity and the ecological, geological, and socioeconomic functions it supports. The persistence of those essential functions will depend on whether coral‐reef management is able to rebalance the competing processes of reef accretion and erosion. Here, we reconstructed census‐based carbonate budgets of 46 reefs throughout the Florida Keys from 1996 to 2019. We evaluated the environmental and ecological drivers of changing budget states and compared historical trends in reef‐accretion potential to millennial‐scale baselines of accretion from reef cores and future projections with coral restoration. We found that historically, most reefs had positive carbonate budgets, and many had reef‐accretion potential comparable to the ~3 mm year−1 average accretion rate during the peak of regional reef building ~7000 years ago; however, declines in reef‐building Acropora palmata and Orbicella spp. corals following a series of thermal stress events and coral disease outbreaks resulted in a shift from positive to negative budgets for most reefs in the region. By 2019, only ~15% of reefs had positive net carbonate production. Most of those reefs were in inshore, Lower Keys patch‐reef habitats with low water clarity, supporting the hypothesis that environments with naturally low irradiance may provide a refugia from thermal stress. We caution that our estimated carbonate budgets are likely overly optimistic; comparison of reef‐accretion potential to measured accretion from reef cores suggests that, by not accounting for the role of nonbiological physical and chemical erosion, census‐based carbonate budgets may underestimate total erosion by ~1 mm year−1 (−1.15 kg CaCO3 m−2 year−1). Although the present state of Florida's reefs is dire, we demonstrate that the restoration of reef‐building corals has the potential to help mitigate declines in reef accretion in some locations, which could allow some key ecosystem functions to be maintained until the threat of global climate change is addressed.

A global synthesis of the current knowledge on the taxonomic and geographic distribution of major coral diseases

Although knowledge on the diseases affecting corals has been accumulating exponentially since the 2000s, even more effort is required to summarize and guide further investigation. Here, we used the Web of Science database to review 226 studies published, between 2000 and 2020, to identify the major geographic and taxonomic gaps in the literature, and propose future directions for the study of coral diseases. We classified the studies according to the ocean, ecoregion, coral species, disease types, approach (e.g., observational or experimental), and depth. In total, 22 types of diseases were reported for 165 coral species. Acropora spp. was the most studied taxa with 12 types of diseases and 8.2% of the records. Black band, white plague, white syndromes, skeletal eroding, dark spot, and yellow band were the six most common diseases, accounting together for 76.8% of the records. As expected, most studies were conducted in the Caribbean and Indo-Pacific (34.0% and 28.7%, respectively), but only in 44 of the 141 global ecoregions that harbour corals. Observational approaches were the most frequent (75.6% of the records), while experimental approaches accounted for 19.9% and were mainly done on Acropora. The vast majority of studies (∼98%) were performed in shallow waters (<30 m depth). We conclude that over the past two decades, coral diseases have been assessed on a very small fraction of coral species, in very few locations around the globe, and at a limited range of their depth distribution. While monitoring bleaching is mandatory for reef ecology and conservation, the ecoepidemiology of coral diseases deserves more space in the research agenda of reef ecosystems.

The role of coral diseases in the flattening of a Caribbean Coral Reef over 23 years

Coral diseases acting synergistically with other environmental stressors are a growing problem for Caribbean reefs. Hard coral cover, coral traits, and coral diseases were examined from 1999 to 2021 for Akumal reef, located in the Northern Mexican Caribbean. The 45 recorded coral species were classified into life-history strategies: competitive, stress-tolerant, and weedy, associated with different framework-building capacities. Results indicate that cumulative impacts of coral diseases outbreaks in the last two decades, in synergy with the effects of coastal development and thermal stressors, have decreased significantly cover and abundance of major reef-building corals, shifting the dominance of the coral assemblage to species belonging to non-framework weedy life history strategy, corresponding to a low Reef Functional Index. Due to the relevant role of coral diseases in shaping coral assemblages, addressing current, and preventing future coral disease outbreaks through integrated management strategies, will be paramount to preserving physical functionality in Caribbean reefs.

Effect of Various Local Anthropogenic Impacts on the Diversity of Coral Mucus-Associated Bacterial Communities

The global continued decline in coral reefs is intensifying the need to understand the response of corals to local environmental stressors. Coral-associated bacterial communities have been suggested to have a swift response to environmental pollutants. This study aims to determine the variation in the bacterial communities associated with the mucus of two coral species, Pocillopora damicornis (Linnaeus, 1758) and Stylophora pistillata (Esper, 1792), and the coral-surrounding seawater from three areas exposed to contamination at the Jordanian coast of the Gulf of Aqaba (Red Sea), and also explores the antibacterial activity of these bacteria. Corals were collected from three contaminated zones along the coast, and the bacteria were quantified and identified by conventional morphological and biochemical tests, as well as 16S rRNA gene sequencing. The average number of bacteria significantly varied among the coral mucus from the sampling zones and between the coral mucus and the surrounding seawater. The P. damicornis mucus-associated bacterial community was dominated by members of the classes Gammaproteobacteria, Cytophagia, and Actinomycetia, while the mucus of S. pistillata represented higher bacterial diversity, with the dominance of the bacterial classes Gammaproteobacteria, Actinomycetia, Alphaproteobacteria, and Bacilli. The effects of local anthropogenic impacts on coral mucus bacterial communities were represented in the increased abundance of bacterial species related to coral diseases. Furthermore, the results demonstrated the existence of bacterial isolates with antibacterial activity that possibly acted as a first line of defense to protect and maintain the coral host against pathogens. Indeed, the dynamics of coral-associated microbial communities highlight the importance of holistic studies that focus on microbial interactions across the coral reef ecosystem.

A health survey of the reef forming scleractinian cold-water corals Lophelia pertusa and Madrepora oculata in a remote submarine canyon on the European continental margin, NE Atlantic

Monitoring of cold-water corals (CWCs) for pathogens and diseases is limited due to the environment, protected nature of the corals and their habitat and as well as the challenging and sampling effort required. It is recognised that environmental factors such as temperature and pH can expedite the ability of pathogens to cause diseases in cold-water corals therefore the characterisation of pathogen diversity, prevalence and associated pathologies is essential. The present study combined histology and polymerase chain reaction (PCR) diagnostic techniques to screen for two significant pathogen groups (bacteria of the genus Vibrio and the protozoan Haplosporidia) in the dominant NE Atlantic deep-water framework corals Lophelia pertusa (13 colonies) and Madrepora oculata (2 colonies) at three sampling locations (canyon head, south branch and the flank) in the Porcupine Bank Canyon (PBC), NE Atlantic. One M. oculata colony and four L. pertusa colonies were collected from both the canyon flank and the south branch whilst five L. pertusa colonies were collected from the canyon head. No pathogens were detected in the M. oculata samples. Neither histology nor PCR detected Vibrio spp. in L. pertusa, although Illumina technology used in this study to profile the CWCs microbiome, detected V. shilonii (0.03%) in a single L. pertusa individual, from the canyon head, that had also been screened in this study. A macroborer was observed at a prevalence of 0.07% at the canyon head only. Rickettsiales-like organisms (RLOs) were visualised with an overall prevalence of 40% and with a low intensity of 1 to 4 (RLO) colonies per individual polyp by histology. L. pertusa from the PBC canyon head had an RLO prevalence of 13.3% with the highest detection of 26.7% recorded in the south branch corals. Similarly, unidentified cells observed in L. pertusa from the south branch (20%) were more common than those observed in L. pertusa from the canyon head (6.7%). No RLOs or unidentified cells were observed in corals from the flank. Mean particulate organic matter concentration is highest in the south branch (2,612 μg l−1) followed by the canyon head (1,065 μg l−1) and lowest at the canyon flank (494 μg l−1). Although the route of pathogen entry and the impact of RLO infection on L. pertusa is unclear, particulate availability and the feeding strategies employed by the scleractinian corals may be influencing their exposure to pathogens. The absence of a pathogen in M. oculata may be attributed to the smaller number of colonies screened or the narrower diet in M. oculata compared to the unrestricted diet exhibited in L. pertusa, if ingestion is a route of entry for pathogen groups. The findings of this study also shed some light on how environmental conditions experienced by deep sea organisms and their life strategies may be limiting pathogen diversity and prevalence.

Coral disease on fungiidae at Sop Island, Sorong, Papua Barat

This research is located at Sop Island, Sorong, West Papua. The data was collected using the Belt Transect method, stretching a line for 50 meters with a width of vision for 2.5 meters to the left and 2.5 meters to the right. The depth of the transect is 5 meters, recorded all genera from Family Fungiidae. Five genera were found on The Sop Island, namely Ctenactis, Fungia, Herpolitha, Polyphyllia, and Sandalolitha, but only Ctenactis, Fungia, and Sandalolitha were found on the three sites of observation. Fungia is the most abundant genera found at Sop Island. So, however, the study also found many unhealthy symptoms that infected Fungia. Of the three observation sites, six categories of unhealthy coral are found: Tissue Loss - non-predation - Coloured Band Disease, Tissue Discoloration - White, Tissue Discoloration non-white, Compromised Health Growth Anomalies, and Unknown. The most common categories infected with the Fungiidae at Sop Island are Tissue Loss - non-predation - Coloured Band Disease, Tissue Discoloration - White. Agonizingly, researchers found coral disease at every site.

Feeding Behavior of Coralliophila sp. on Corals Affected by Caribbean Ciliate Infection (CCI): A New Possible Vector?

Coral reefs in the Caribbean are known to be affected by many coral diseases, yet the ecology and etiology of most diseases remain understudied. The Caribbean ciliate infection (CCI) caused by ciliates belonging to the genus Halofolliculina is a common disease on Caribbean reefs, with direct contact considered the most likely way through which the ciliates can be transmitted between infected and healthy colonies. Here we report an observation regarding a Coralliophila sp. snail feeding in proximity to a cluster of ciliates forming the typical disease band of CCI. The result of this observation is twofold. The feeding behavior of the snail may allow the passive attachment of ciliates on the body or shell of the snail resulting in indirect transport of the ciliates among colonies, which makes it eligible as a possible disease vector. Alternatively, the lesions created from snail feeding may enhance the progression of the ciliates already present on the coral as well as promoting additional infections allowing pathogens to enter through the feeding scar.

Small no‐take areas benefit hard corals more than regulation through fishing permits

Abstract Situated in the coral triangle, the Philippines hosts some of the world's most diverse coral reefs. Yet there are few national marine protected areas (MPAs) in place that coincide with these reefs. Municipal MPAs partially alleviate this issue but a controlled comparison of the effects of different small‐scale management strategies on coral reefs is lacking. Danjugan Island Marine Reserve and Sanctuaries (DIMRS) is one of these community‐based MPAs that encompasses a collection of small (0.3–0.34 km2) marine reserves situated in a larger MPA where fishing is regulated through permits. The unique juxtaposition of different management strategies within DIMRS was used as a model system to test whether reserves are better for corals than limited fishing permits by comparing ecosystem indicators (coral cover, bleaching, disease, and morphological diversity). Total and live hard corals were 169% and 204% more abundant inside than outside no‐take zones in 2016. This distinction increased between 2002 and 2016 as a result of a more marked decrease in coral cover over time in the partially protected zones. A 70% higher coral community evenness outside the reserves further suggests that scleractinian coral communities on fished reefs are more disturbed. Live coral cover within the MPAs of DIMRS in 2016 (39 ± 4%) is above the current mean for Philippine reefs (23%) and is comparable with the long‐term average for reefs situated within Philippine MPAs (36%). This study suggests that exceptionally small reserves may benefit hard corals more than regulation via fishing permits.

CORAL DISEASES IN NORTHEASTERN BRAZILIAN REEFS

In the last decade, corals from northeastern Brazil have experienced bleaching events linked to thermal anomalies, the consequences of which have been the appearance of disease outbreaks affecting different species. As a way to explain and monitoring diseases progression and other characteristics regarding the identification in the field for coral diseases, this article aimed to demonstrate the particularities that follows each diseases symptom. This study presents the results of an assessment of the presence of coral diseases on six coastal reefs in northeastern Brazil, including marine protected areas. After 300 hours of visual censuses, a total of 875 colonies were observed; of these, 114 colonies had some disease, representing 13.02% of the colonies analyzed. Five diseases/syndromes were recorded in four host coral species: white syndrome, white plague, red band, dark spots, and white band. This is the first record of white band on the Brazilian coast. The massive coral Siderastrea stellata showed colonies with all registered diseases, which arouses great concern for conservation of the Brazilian coast.

Phosphate enrichment induces increased dominance of the parasite Aquarickettsia in the coral Acropora cervicornis.

Nutrient pollution is linked to coral disease susceptibility and severity, but the mechanism behind this effect remains underexplored. A recently identified bacterial species, ‘Ca. Aquarickettsia rohweri,’ is hypothesized to parasitize the Caribbean staghorn coral, Acropora cervicornis, leading to reduced coral growth and increased disease susceptibility. Aquarickettsia rohweri is hypothesized to assimilate host metabolites and ATP and was previously demonstrated to be highly nutrient-responsive. As nutrient enrichment is a pervasive issue in the Caribbean, this study examined the effects of common nutrient pollutants (nitrate, ammonium, and phosphate) on a disease-susceptible genotype of A. cervicornis. Microbial diversity was found to decline over the course of the experiment in phosphate-, nitrate-, and combined-treated samples, and quantitative PCR indicated that Aquarickettsia abundance increased significantly across all treatments. Only treatments amended with phosphate, however, exhibited a significant shift in Aquarickettsia abundance relative to other taxa. Furthermore, corals exposed to phosphate had significantly lower linear extension than untreated or nitrate-treated corals after 3 weeks of nutrient exposure. Together these data suggest that while experimental tank conditions, with an elevated nutrient regime associated with coastal waters, increased total bacterial abundance, only the addition of phosphate significantly altered the ratios of Aquarickettsia compared to other members of the microbiome.

Decreased Photosynthetic Efficiency in Response to Site Translocation and Elevated Temperature Is Mitigated with LPS Exposure in Porites astreoides Symbionts

Coral reefs have been detrimentally impacted causing health issues due to elevated ocean temperatures as a result of increased greenhouse gases. Extreme temperatures have also exacerbated coral diseases in tropical reef environments. Numerous studies have outlined the impacts of thermal stress and disease on coral organisms, as well as understanding the influence of site-based characteristics on coral physiology. However, few have discussed the interaction of all three. Laboratory out-planting restoration projects have been of importance throughout impacted areas such as the Caribbean and southern Florida in order to increase coral cover in these areas. This study analyzes photosynthetic efficiency of Porites astreoides from the lower Florida Keys after a two-year reciprocal transplant study at inshore (Birthday reef) and offshore (Acer24 reef) sites to understand acclimation capacity of this species. Laboratory experiments subjected these colonies to one of three treatments: control conditions, increases in temperature, and increases in temperature plus exposure to an immune stimulant (lipopolysaccharide (LPS)) to determine their influence on photosynthetic efficiency and how stress events impact these measurements. In addition, this study is a continuation of previous studies from this group. Here, we aim to understand if these results are static or if an acclimation capacity could be found. Overall, we observed site-specific influences from the Acer24 reef site, which had significant decreases in photosynthetic efficiencies in 32 °C treatments compared to Birthday reef colonies. We suggest that high irradiance and lack of an annual recovery period from the Acer24 site exposes these colonies to significant photoinhibition. In addition, we observed significant increases in photosynthetic efficiencies from LPS exposure. We suggest host-derived antioxidants can mitigate the negative impacts of increased thermal stress. Further research is required to understand the full complexity of host immunity and symbiont photosynthetic interactions.

The role of predators in coral disease dynamics

AbstractCoral disease is becoming increasingly problematic on reefs worldwide. However, most coral disease research has focused on the abiotic drivers of disease, potentially overlooking the role of species interactions in disease dynamics. Coral predators in particular can influence disease by breaking through protective tissues and exposing corals to infections, vectoring diseases among corals, or serving as reservoirs for pathogens. Numerous studies have demonstrated the relationship between corallivores and disease in certain contexts, but to date there has been no comprehensive synthesis of the relationships between corallivores and disease, which hinders our understanding of coral disease dynamics. To address this void, we identified 65 studies from 26 different ecoregions that examine this predator–prey-disease relationship. Observational studies found over 20 positive correlations between disease prevalence and corallivore abundance, with just four instances documenting a negative correlation between corallivores and disease. Studies found putative pathogens in corallivore guts and experiments demonstrated the ability of corallivores to vector pathogens. Corallivores were also frequently found infesting disease margins or targeting diseased tissues, but the ecological ramifications of this behavior remains unknown. We found that the impact of corallivores was taxon-dependent, with most invertebrates increasing disease incidence, prevalence, or progression; fish showing highly context-dependent effects; and xanthid crabs decreasing disease progression. Simulated wounding caused disease in many cases, but experimental wound debridement slowed disease progression in others, which could explain contrasting findings from different taxa. The negative effects of corallivores are likely to worsen as storms intensify, macroalgal cover increases, more nutrients are added to marine systems, and water temperatures increase. As diseases continue to impact coral reefs globally, a more complete understanding of the ecological dynamics of disease—including those involving coral predators—is of paramount importance to coral reef conservation and management.

Transforming Palmyra Atoll to native-tree dominance will increase net carbon storage and reduce dissolved organic carbon reef runoff.

Native forests on tropical islands have been displaced by non-native species, leading to calls for their transformation. Simultaneously, there is increasing recognition that tropical forests can help sequester carbon that would otherwise enter the atmosphere. However, it is unclear if native forests sequester more or less carbon than human-altered landscapes. At Palmyra Atoll, efforts are underway to transform the rainforest composition from coconut palm (Cocos nucifera) dominated to native mixed-species. To better understand how this landscape-level change will alter the atoll's carbon dynamics, we used field sampling, remote sensing, and parameter estimates from the literature to model the total carbon accumulation potential of Palmyra's forest before and after transformation. The model predicted that replacing the C. nucifera plantation with native species would reduce aboveground biomass from 692.6 to 433.3 Mg C. However, expansion of the native Pisonia grandis and Heliotropium foertherianum forest community projected an increase in soil carbon to at least 13,590.8 Mg C, thereby increasing the atoll's overall terrestrial carbon storage potential by 11.6%. Nearshore sites adjacent to C. nucifera canopy had a higher dissolved organic carbon (DOC) concentration (110.0 μMC) than sites adjacent to native forest (81.5 μMC), suggesting that, in conjunction with an increase in terrestrial carbon storage, replacing C. nucifera with native forest will reduce the DOC exported from the forest into in nearshore marine habitats. Lower DOC levels have potential benefits for corals and coral dependent communities. For tropical islands like Palmyra, reverting from C. nucifera dominance to native tree dominance could buffer projected climate change impacts by increasing carbon storage and reducing coral disease.

Combining tangential flow filtration and size fractionation of mesocosm water as a method for the investigation of waterborne coral diseases.

The causative agents of most coral diseases today remain unknown, complicating disease response and restoration efforts. Pathogen identifications can be hampered by complex microbial communities naturally associated with corals and seawater, which create complicating "background noise" that can potentially obscure a pathogen's signal. Here, we outline an approach to investigate waterborne coral diseases that use a combination of coral mesocosms, tangential flow filtration, and size fractionation to reduce the impact of this background microbial diversity, compensate for unknown infectious dose, and further narrow the suspect pool of potential pathogens. As proof of concept, we use this method to compare the bacterial communities shed into six Montastraea cavernosa coral mesocosms and demonstrate this method effectively detects differences between diseased and healthy coral colonies. We found several amplicon sequence variants (ASVs) in the diseased mesocosms that represented 100% matches with ASVs identified in prior studies of diseased coral tissue, further illustrating the effectiveness of our approach. Our described method is an effective alternative to using coral tissue or mucus to investigate waterborne coral diseases of unknown etiology and can help more quickly narrow the pool of possible pathogens to better aid in disease response efforts. Additionally, this versatile method can be easily adapted to characterize either the entire microbial community associated with a coral or target-specific microbial groups, making it a beneficial approach regardless of whether a causative agent is suspected or is completely unknown.

Bacterial Metabolic Potential and Micro-Eukaryotes Enriched in Stony Coral Tissue Loss Disease Lesions

The epizootic disease outbreak known as stony coral tissue loss disease (SCTLD) is arguably the most devastating coral disease in recorded history. SCTLD emerged off the coast of South Florida in 2014 and has since moved into the Caribbean, resulting in coral mortality rates that have changed reef structure and function. Currently, the cause of SCTLD is unknown, but there is evidence from 16S rRNA gene sequencing and bacterial culture studies that the microbial community plays a role in the progression of SCTLD lesions. In this study, we applied shotgun metagenomics to characterize the potential function of bacteria, as well as the composition of the micro-eukaryotic community, associated with SCTLD lesions. We re-examined samples that were previously analyzed using 16S rRNA gene high-throughput sequencing from four coral species: Stephanocoenia intersepta, Diploria labyrinthiformis, Dichocoenia stokesii, and Meandrina meandrites. For each species, tissue from apparently healthy (AH) corals, and unaffected tissue (DU) and lesion tissue (DL) on diseased corals, were collected from sites within the epidemic zone of SCTLD in the Florida Keys. Within the micro-eukaryotic community, the taxa most prominently enriched in DL compared to AH and DU tissue were members of Ciliophora. We also found that DL samples were relatively more abundant in less energy-efficient pathways like the pentose phosphate pathways. While less energy-efficient processes were identified, there were also relatively higher abundances of nucleotide biosynthesis and peptidoglycan maturation pathways in diseased corals compared to AH, which suggests there was more bacteria growth in diseased colonies. In addition, we generated 16 metagenome-assembled genomes (MAGs) belonging to the orders Pseudomonadales, Beggiatoales, Rhodobacterales, Rhizobiales, Rs-D84, Flavobacteriales, and Campylobacterales, and all MAGs were enriched in DL samples compared to AH samples. Across all MAGs there were antibiotic resistance genes that may have implications for the treatment of SCTLD with antibiotics. We also identified genes and pathways linked to virulence, such as nucleotide biosynthesis, succinate dehydrogenase, ureases, nickel/iron transporters, Type-1 secretion system, and metalloproteases. Some of these enzymes/pathways have been previously targeted in the treatment of other bacterial diseases and they may be of interest to mitigate SCTLD lesion progression.

Four-Year Field Survey of Black Band Disease and Skeletal Growth Anomalies in Encrusting Montipora spp. Corals around Sesoko Island, Okinawa

The Indo-Pacific zooxanthellate scleractinian coral genus Montipora is the host of many coral diseases. Among these are cyanobacterial Black Band Disease (BBD) and Skeletal Growth Anomalies (GAs), but in general data on both diseases are lacking from many regions of the Indo-Pacific, including from Okinawa, southern Japan. In this study, we collected annual prevalence data of Black Band Disease (BBD) and Skeletal Growth Anomalies (GAs) affecting the encrusting form of genus Montipora within the shallow reefs of the subtropical Sesoko Island (off the central west coast of Okinawajima Island) from summer to autumn for four years (2017 to 2020). In 2020 Montipora percent coverage and colony count were also assessed. Generalized Linear Models (GLM) were used to understand the spatial and temporal variation of both BBD and GAs in the nearshore (NE) and reef edge (RE) sites, which revealed higher probability of BBD occurrence in RE sites. BBD prevalence was significantly higher in 2017 in some sites than all other years with site S12 having significant higher probability during all four surveyed years. In terms of GAs, certain sites in 2020 had higher probability of occurrence than during the other years. While the general trend of GAs increased from 2017 to 2020, it was observed to be non-fatal to colonies. In both diseases, the interaction between sites and years was significant. We also observed certain BBD-infected colonies escaping complete mortality. BBD progression rates were monitored in 2020 at site S4, and progression was related to seawater temperatures and was suppressed during periods of heavy rain and large strong typhoons. Our results suggest that higher BBD progression rates are linked with high sea water temperatures (SST &gt; bleaching threshold SST) and higher light levels (&gt;1400 µmol m−2 s−1), indicating the need for further controlled laboratory experiments. The current research will help form the basis for continued future research into these diseases and their causes in Okinawa and the Indo-Pacific Ocean.

Short communication: Algal genotypes in White Syndrome infected coral Acropora muricata from the Karimunjawa Islands, Indonesia

Abstract. Wijayanti DP, Nadia M, Indrayanti E, Haryanti D, Bachtiar M. 2021. Short communication: Algal genotypes in White Syndrome infected coral Acropora muricata from the Karimunjawa Islands, Indonesia. Biodiversitas 23: 415-423. The physiological equilibrium of the coral holobiont may help the corals to survive under various environmental threats. The symbiont genotype is thought to play an important role in the host's susceptibility to thermal stress and coral disease incidence. We identified the Symbiodiniaceae diversity of coral Acropora muricata infected by White Syndrome (WS). Samples were collected from Cemara Kecil Island and Barakuda Beach, Kemujan Island, Karimunjawa Islands. We applied DNA barcoding of 28S nuclear ribosomal RNA gene of the healthy colonies, healthy tissue, and lesions of diseased colonies to perform their symbiont type identification. There were two different symbiont types observed from the phylogenetic analysis, which formed two clades. A clade consisting all Cemara Kecil Island samples while the other with all Barakuda Beach samples except for one. All samples harbored symbiont types from the genus Cladocopium. The members of the genus were reported to have various physiological properties which may support the host resilience when facing the disease. A robust study is needed to reveal the influence of symbiont genotypes on the occurrence of coral disease and the susceptibility of the coral host.

珊瑚礁生态系统病毒研究进展

PDF HTML阅读 XML下载 导出引用 引用提醒 珊瑚礁生态系统病毒研究进展 DOI: 10.5846/stxb202005021086 作者: 作者单位: 作者简介: 通讯作者: 中图分类号: 基金项目: 国家自然科学基金重大项目（42090041）；国家自然科学基金重点项目（42030502）；广西南海珊瑚礁研究重点实验室自主基金项目（GXLSCRSCS2021103） A review of recent researches on viruses in coral reef ecosystem Author: Affiliation: Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:病毒对珊瑚礁生态系统中的生物进化、生物地球化学循环、珊瑚疾病等方面具有重要的生态影响。随着珊瑚礁的全球性退化，病毒在珊瑚礁生态系统中的功能与危害日益显现。综述了珊瑚礁生态系统中病毒的研究现状与进展，包括：（1）珊瑚礁病毒的多样性与分布特征（水体、宿主、核心病毒组）；（2）珊瑚礁病毒的生态功能（感染方式、促进生物进化、生物地球化学循环）；（3）珊瑚礁病毒对全球气候变化的响应（热压力、珊瑚疾病）。总体而言，珊瑚礁生态系统具有极高的病毒多样性，所发现的60个科占已知所有病毒科数量的58%。珊瑚的核心病毒组主要由双链DNA病毒、单链DNA病毒、单链逆转录病毒所组成，珊瑚黏液层对病毒具有富集作用。"Piggyback-the-Winner"（依附-胜利）是病毒在珊瑚礁中主要的生物动力学模式，其可通过水平基因迁移的方式促进礁区生物进化。病毒可通过裂解细菌与浮游藻类的途径参与珊瑚礁的生物地球化学循环，尤其是碳循环与氮循环过程。此外，病毒还具有介导珊瑚热白化与直接引发珊瑚疾病的能力，这会影响珊瑚礁生态系统应对气候变化的适应性与恢复力。基于国际上的研究进展综述，结合南海珊瑚礁生态现状提出以下研究方向，以期促进我国珊瑚礁病毒学的发展：（1）开展南海珊瑚礁中病毒多样性的识别及其时-空分布特征研究；（2）探索病毒对南海珊瑚热白化、珊瑚疾病的介导作用及其与气候变化的关系；（3）揭示病毒对南海珊瑚礁生物地球化学循环的贡献。 Abstract:Viruses have an important ecological impact on the biological evolution, biogeochemical cycle, and coral diseases in coral reef ecosystems. With the global degradation of coral reefs, the functions and hazards of viruses in coral reef regions have become increasingly prominent. In this article, recent researches on viruses in coral reef ecosystems were reviewed, which included:(1) The diversity and distribution characteristics of viruses in coral reef ecosystem (sea water, host and core coral virome); (2) Ecological function of viruses in coral reef ecosystem (infection pattern, promoting biological evolution, and biogeochemical cycle); (3) Viruses response to global climate change in coral reef ecosystem (thermal stress and coral diseases). Accordingly, coral reef ecosystems have an extremely high viral richness and diversity. About 60 virus families are reported in coral reef ecosystems around the world, which account for 58% of all known viral families. Also, the core coral virome is manly composed of double-stranded DNA virus (dsDNA virus), single-stranded DNA virus (ssDNA virus) and retrovirus. The viruses in coral surface mucus layer are more abundant and diverse, due to enrichment with viruses from around environment in coral reef ecosystem. "Piggyback-the-Winner" is the main biodynamic mode of viruses in coral reefs, which indicates that viruses can promote the evolution of organisms by horizontal gene transduction in reef regions. In addition, viruses can participate in the carbon and nitrogen cycles of coral reefs by lysing bacteria and planktonic algae, respectively, which plays an important role in biogeochemical cycles of coral reef ecosystem. It's worth noting that viruses have ability to mediate coral thermal bleaching, which has closely associations with Phycodnaviridae and Herpesviridae. Moreover, viruses can also lead to coral diseases (e.g., white plague, white band disease and yellow blotch), which can affect the adaptability and resilience of coral reefs to global climate change. Herein, based on a systematic review of international research progress and current ecological status of coral reefs in the South China Sea, this article proposes the following research directions, in order to promote the development of coral reef virology:(1) The diversity and spatial-temporal distribution characteristics of viruses in coral reefs from the South China Sea; (2) The mediation effect of viruses on coral thermal bleaching and diseases in the South China Sea, and their relationship with intensified global climate change; (3) The contribution of viruses in biogeochemical cycles (e.g., carbon and nitrogen cycles) of coral reef ecosystems in the South China Sea. 参考文献 相似文献 引证文献