Infected Corals Research Articles

Northern coral triangle coral ciliates diseases and disease prevention: A first record

This study is the first to report ciliate infection on soft corals in the Northern Coral Triangle. Infected Briareum violacea will undergo tissue ulceration and death within a short period of time. This ciliate was identified as Scuticociliatia sp. through 18S rRNA gene identification. In this study, the body length of the ciliate was approximately 80–85 μm before parasitizing the B. violacea. After being parasitizing, the body length was approximately 200–250 μm, and the body width was 50 μm. Body size increased three times after parasitism. According to observations, ciliates will first parasitize the coral endoderm in the early stage of infection, and no ciliates were found in the ectoderm. Preliminary judgment suggests that it may invade the coral endoderm through the mouth for parasitism. After parasitism, the ciliate eats the coral tissue and zooxanthellae. The antioxidant enzymes SOD, CAT, and MDA of infected corals were significantly increased, which also means that the corals are in a stress response. Ciliates will eat the zooxanthellae in the coral body, resulting in a significant reduction in the number of zooxanthellae and chlorophyll a. To effectively prevent and treat this disease, Combretum indicum extract was used in this study. It is a tropical plant commonly used medicinally to treat roundworms, pinworms and parasitic diseases. The results showed that at a concentration of 1500–2500 ppm, Combretum indicum extract can be used to treat ciliates and can applied via medicinal bath therapy for long periods without causing coral stress reactions. The results of this study regarding coral disease prevention are in line with SDG 14 and promote the practical application of coral reef ecological sustainability and large-scale coral aquaculture.

Spatio-temporal variation in progression rates of black band disease between Pramuka Island and Pari Island of the Seribu Islands, Indonesia

Black band disease (BBD) is one of the oldest recognized diseases of scleractinian corals. This disease is little known on the variation of progression rates across relatively small spatial scales and how local variations in the environment can impact prevalence and spread. The purpose of this study was to explore the progression of BBD on genus Montipora in relation to spatio-temporal environmental parameters in two islands of the Seribu Islands, North Jakarta, Indonesia during dry season and rainy season. Monthly underwater pictures were taken for determining the progress of disease level. Interestingly, the progression rate of the disease recorded at Pramuka Island was higher (8.10 cm2 day-1) than the one at Pari Island (3.79 cm2 day-1). In Pramuka Island, the infected corals had almost 89% of the dead surface, compared to only 68% at Pari Island. Similar to other studies in the region, we confirmed that the disease progressed faster during the dry season, where the environmental parameters, such as temperature, light intensity, and phosphate, were starting to increase, while total organic matter, current flow rates, and turbidity were lower. Progression of the disease was significantly different between seasons (p<0.001), but not between sites (p=0.118). Therefore, the progress of BBD has a higher impact at the more populated Pramuka island than at the less populated Pari Island, in addition to the influence of environmental parameters on coral vulnerability to diseases.

Distinct patterns of coral lesion composition from national/quasi-national marine parks of Kerama and Yoron Islands, Ryukyu Archipelago

A wide variety of coral communities are found in the Ryukyu Archipelago in southern Japan. Although reports of coral diseases and lesions in this region have increased since the 2000's, the variations of coral diseases among islands are somewhat limited. In this study, we conducted surveys to reveal the coral lesion assemblage and patterns in the marine national park area of Kerama Island and the quasi-national park on Yoron Island. Both sites are located 150 km away apart in the Ryukyu Archipelago. In total, 12 gross lesions were found in 30 coral genera. Corals in Yoron Island had 22% greater gross lesion abundance than Kerama Island (13.40 ± 1.36%) with an overall mean lesion abundance of 16.83 ± 1.66% (mean ± SE). Each Island shows a distinct pattern and group of coral lesion compositions. The disease lesion group of 7.21 ± 1.37% was dominated by White Syndrome (WS) and Black Band Disease (BBD), which severely infected various coral genera in Yoron Island. Corals in Kerama Island were predominantly affected by non-disease group lesion (9.76 ± 1.33%), such as Chalinula nematifera (CN) sponge overgrowing on the coral surface. Corals in the genus Pachyseris were highly susceptible (17.79%) to the diseases on Yoron Island, while Acroporid corals were the most susceptible (8.32%) to the diseases on Kerama Island. In addition, Porites were affected by disease and non-disease lesions from all sites in both Kerama and Yoron. These findings highlight the emergence of potential threats to coral communities in these national/quasi-national marine parks in Kerama and Yoron Island, which may be a factor limiting the survival and growth of key Scleractinian coral taxa. In addition, immediate consideration of environmental monitoring may be required to prevent coral disease outbreaks in the future.

Different disease inoculations cause common responses of the host immune system and prokaryotic component of the microbiome in Acropora palmata.

Reef-building corals contain a complex consortium of organisms, a holobiont, which responds dynamically to disease, making pathogen identification difficult. While coral transcriptomics and microbiome communities have previously been characterized, similarities and differences in their responses to different pathogenic sources has not yet been assessed. In this study, we inoculated four genets of the Caribbean branching coral Acropora palmata with a known coral pathogen (Serratia marcescens) and white band disease. We then characterized the coral's transcriptomic and prokaryotic microbiomes' (prokaryiome) responses to the disease inoculations, as well as how these responses were affected by a short-term heat stress prior to disease inoculation. We found strong commonality in both the transcriptomic and prokaryiomes responses, regardless of disease inoculation. Differences, however, were observed between inoculated corals that either remained healthy or developed active disease signs. Transcriptomic co-expression analysis identified that corals inoculated with disease increased gene expression of immune, wound healing, and fatty acid metabolic processes. Co-abundance analysis of the prokaryiome identified sets of both healthy-and-disease-state bacteria, while co-expression analysis of the prokaryiomes' inferred metagenomic function revealed infected corals' prokaryiomes shifted from free-living to biofilm states, as well as increasing metabolic processes. The short-term heat stress did not increase disease susceptibility for any of the four genets with any of the disease inoculations, and there was only a weak effect captured in the coral hosts' transcriptomic and prokaryiomes response. Genet identity, however, was a major driver of the transcriptomic variance, primarily due to differences in baseline immune gene expression. Despite genotypic differences in baseline gene expression, we have identified a common response for components of the coral holobiont to different disease inoculations. This work has identified genes and prokaryiome members that can be focused on for future coral disease work, specifically, putative disease diagnostic tools.

Evaluation of Forsythia suspensa extract for drug therapy of ciliate infection in coral (Goniopora columna)

Coral aquaculture is an emerging aquaculture industry. In recent years, ciliate infestation has become a serious hazard to wild and captive corals. Our previous research found that infected corals can fester or die within 72 h, posing a serious threat to large-scale coral aquaculture. Little research has been done on the treatment of coral ciliate disease. Therefore, drugs that seek effective treatment and avoid stress responses to corals will be applied to large-scale coral aquaculture. Forsythia suspensa is a common traditional Chinese medicine with anti-inflammatory, anticancer, antibacterial, antiviral, and insecticidal functions. In this study, the F. suspensa extract at concentrations of 0.5%, 1%, 1.25%, 1.75%, 2.25%, and 2.75% was used to conduct a virulence test on ciliates and evaluate the therapeutic effect on Goniopora columna. The uninfected ciliates are the N-group, and the infected ciliates without drug treatment, the control group, are the C-group. After the experiment, the effects of the F. suspensa extract on the ciliate stress response of corals were evaluated by using the virulence test and calculating damage to histopathology, zooxanthellae, chlorophyll a, and three antioxidant enzymes, namely, superoxide dismutase (SOD), catalase (CAT) and malondialdehyde (MDA). The results showed that the LC50 value of the F. suspensa extract was approximately 1.52%, and when the concentration was increased to 1.75%, the ciliates could be completely killed within 10 min of medicated bathing. The SOD, CAT, and MDA of G. columna under the 1.75% treatment were lower than those of the other treatment groups and higher than only those of the N-group. The zooxanthellae, chlorophyll a, and survival rate were not significantly different from those in the N-group. Upon histological examination, no ciliates or vacuum were found in coral tissue 72 h after treatment. In conclusion, 1.75% Forsythia suspensa extract is effective in the treatment of G. columna ciliate infection without causing a strong stress response in corals. Forsythia suspensa can be effectively applied in the prevention of ciliate diseases in large-scale coral aquaculture.

Prevalence and abundance of coral disease in Aceh Besar regency Aceh, Indonesia

The aims of this research was to knew the prevalence, abundance and types of coral diseases detected in Peukan Bada Aceh Besar Regency. Method used in this research was a 20x2m belt transect with 3 replicates. Results show that the prevalence value was between 27,94% – 58,25%. The value was quite higher if compared with other prevalence on some place in indonesia. Average value of coral disease abundance in this research was 0,23 ind/m2. There was 13 types of coral disease found during sampling, including Fish Bite, Drupella Predation, Acanthaster planci Predation, White Syndrome, Ulcerative White Spot, Focal Bleaching, Non-Focal Bleaching, Invertebrate Galls, Sponge Overgrowth, Cyanobacteria, Pigmentation Response, Sedimentation Damage, Algae Overgrowth. The most infected coral genus was Acropora with branching growth form.Keywords:AbundanceConditionCoral diseasePrevalence

Prevalence of differential microbiome in healthy, diseased and nipped colonies of corals, Porites lutea in the Gulf of Kachchh, north-west coast of India

Coral reefs are constantly subjected to multiple stresses like diseases and fish predation, which can profoundly influence the coral microbiome. This study investigated the differences in bacterial community structure of healthy, white syndrome affected and blenny nipped coral colonies of Porites lutea, collected from the coral reefs of Gulf of Kachchh, north-west coast of India. Present study observed that the stressed coral colonies harbored more OTUs and contained higher diversity values compared to healthy corals colonies. Similarly, beta diversity analysis indicated the dissimilarities among the three coral samples analyzed. Though the taxonomy analysis indicated bacterial phyla like Proteobacteria, Firmicutes, Bacteroidetes, and Actinobacteria among the entire coral samples studied, there was a variation in their relative abundances. Huge variations were observed in the relative dominance at the bacterial genera level. About 13phyla and 11 genera was identified in healthy coral. The PBN sample was found to contain Proteobacteria, Cyanobacteria, Verrucomicrobia, and Lentisphaerae as dominant phyla and Endozoicomonas, Dyella, Woeseia, and Winogradskyella as dominant genera. The PWS sample contained Proteobacteria, Lentisphaerae, Spirochaetes, and Tenericutes as dominant phyla and Endozoicomonas, Arcobacter, Sunxiuqinia, and Carboxylicivirgia as dominant genera. Among the healthy samples, sequences belonging to Uncultured Rhodospirillaceae were dominant, while Woeseia and sequences belonging to Uncultured Rhodovibrionaceae were dominant among the blenny nipped white syndrome infected corals. Although any previously established pathogen was not identified, present study revealed the presence of a potentially pathogenic bacterium, Arcobacter, among the diseased corals. It also demonstrated a dynamic microbiome among the Porites lutea colonies on subjecting to various stresses.

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.

Evaluation of Clove Extract for Drug Therapy of Ciliate Infection in Coral (Goniopora columna).

Simple SummaryIn recent years, studies have found that coral infectious diseases are gradually spreading. Ciliate disease poses a serious threat to corals, and infected corals will fester and die within a short period of time. Clove is a traditional Chinese medicine. In this study, Clove extract was used to evaluate the treatment of ciliate diseases to achieve safety and to reduce the stress response of corals. Studies have shown that 1500 ppm clove extract can effectively treat ciliate parasitism, and does not affect coral zooxanthellae, chlorophyll a, or stress response. This extract has been successfully applied to a Taiwan coral king coral farm, which will have great significance for large-scale coral aquaculture.In recent years, ciliate infections have caused serious casualties to corals in the ocean. Infected corals die within a short period of time, which not only poses a threat to wild coral reefs, but also has a major impact on large scale aquaculture of coral. Clove is a kind of Chinese medicine with antifungal, antibacterial, antiviral, insecticidal, and other functions. Clove is a natural product. If it can be used in the treatment of coral ciliates, it will reduce this threat to the environment. The clove extract was diluted with sterile seawater to 500 ppm, 1500 ppm, 2500 ppm, 5000 ppm, 7500 ppm, and 10,000 ppm to carry out virulence test on ciliates. The results show that the LC50 value is 1500 ppm, which can cause the death of ciliates in 10 min without causing significant changes in G. columna SOD, CAT, chlorophyll a, and zooxanthellae. In addition, observation of tissue slices revealed that no ciliates and vacuum were found in the G. columna tissue after 10 min of medicated bathing. In summary, 1500 ppm of clove extract can be used for the treatment of coral ciliates.

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.

The abundance of coral disease and compromise health in Sabu Raijua Waters, East Nusa Tenggara

Coral die-offs can be caused by several factors, one of which is the infectious coral disease. Currently, limited data and information are available regarding coral diseases abundance and distribution in Indonesia including Sabu Raijua waters, East Nusa Tenggara. This research aimed to investigate the types and abundance of coral disease and determine the compromise health condition on 12 sites in Sabu-Raijua waters on Sawu Marine National Park. The research showed coral conditions varied from bad to poor. There were eight coral disease types, the highest abundance found atromentous necrosis (0.12 col/m2) in station 11 (Menia 1), and nine compromise health with the highest number of CH types was found at station 12 with its abundance from 0.02 to 0.33 col/m2. The disease abundance were classified as low on the sites, no evidence due to environmental factors. However, a regular survey has to be carried out in the area to monitor the progress and incidence of the coral diseases and measure their future impacts on the coral reef ecosystem of the national park.

Effects of Ciliate Infection on the Activities of Two Antioxidant Enzymes (SOD and CAT) in Captive Coral (Goniopora columna) and Evaluation of Drug Therapy.

Simple SummaryIn recent years, corals have been subjected to severe parasitic ciliates that have led to coral ulceration, bleaching or death. No previous studies have shown a treatment for ciliate infection of coral. In this study, two antioxidant enzymes (SOD and CAT) were used to judge the stress response in Goniopora columna after infection, and KCl and H2O2 were used to evaluate the therapeutic effect. According to the results, KCl 1.5% can effectively treat ciliate parasitism. This research has been successfully applied to the TCK Coral Farm to achieve effective treatment. It is very important for large-scale coral aquaculture.Ciliate infection is a serious parasitic disease of coral. Infected coral rots and dies in a short time. In addition to killing corals by infecting them in the oceans, ciliate infection also poses a threat to corals farmed on a large scale. In this study, two antioxidant enzymes (SOD and CAT) were used to judge the stress response in Goniopora columna after infection, and KCl and H2O2 were used to evaluate the therapeutic effect. The results showed that SOD and CAT increased during the early stage of infection but decreased with the extension of infection time. In terms of drug therapy, it was found that the treatment of ciliate infection with 1.5% of KCl had no significant effect on SOD and CAT of G. columna. The morphological changes of zooxanthellae, chlorophyll a, and coral were not significant. H2O2 leads to a stress response and polyp contraction. In conclusion, 1.5% of KCl can be used in the selection of drugs to treat ciliate infection.

Antipathogenic Activity of Acroporid Bacterial Symbionts Against Brown Band Disease-Associated Bacteria

The coral reefs’ condition in most regions in Indonesia has been declining due to coral diseases, such as Brown Band Disease (BrBD). A treatment for BrBD involves the use of biological control agents that have antagonistic properties against disease-causing agents. This study aimed to isolate bacteria from healthy hard coral, those associated with BrBD, and those that had bioactivities against BrBD. Sampling and identification of corals and BrBD were carried out in March 2015 at the Marine National Park of Karimunjawa. Bacteria from healthy and infected corals were isolated and purified. The isolates were subjected to antipathogenic assay using overlay and agar diffusion methods. Finally, molecular identification of active bacteria was carried out using the 16S rRNA gene amplification. As many as 57 bacterial isolates were obtained from healthy coral, as well as four bacterial isolates from coral with BrBD symptoms. A total of 15 bacterial isolates (26%) showed antipathogenic activity against BrBD-associated bacteria. Three isolates with the strongest antipathogenic activities, i.e., GAMSH 3, KASH 6, and TAPSH 1 were identified by 16S rRNA gene sequences. The results showed that they were aligned to Virgibacillus marismortui (97%), Oceanobacillus iheyensis (97%), and Bacillus cereus (96%), respectively.

Quantifying impacts of stony coral tissue loss disease on corals in Southeast Florida through surveys and 3D photogrammetry.

Since 2014, stony coral tissue loss disease (SCTLD) has contributed to substantial declines of reef-building corals in Florida. The emergence of this disease, which impacts over 20 scleractinian coral species, has generated a need for widespread reef monitoring and the implementation of novel survey and disease mitigation strategies. This study paired SCTLD prevalence assessments with colony-level monitoring to help improve understanding of disease dynamics on both individual coral colonies and at reef-wide scales. Benthic surveys were conducted throughout the northern Florida Reef Tract to monitor the presence/absence of disease, disease prevalence, and coral species affected by SCTLD. Observed SCTLD prevalence was lower in Jupiter and Palm Beach than in Lauderdale-by-the-Sea or St. Lucie Reef, but there were no significant changes in prevalence over time. To assess colony-level impacts of the disease, we optimized a low-cost, rapid 3D photogrammetry technique to fate-track infected Montastraea cavernosa coral colonies over four time points spanning nearly four months. Total colony area and healthy tissue area on fate-tracked colonies decreased significantly over time. However disease lesion area did not decrease over time and was not correlated with total colony area. Taken together these results suggest that targeted intervention efforts on larger colonies may maximize preservation of coral cover. Traditional coral surveys combined with 3D photogrammetry can provide greater insights into the spatiotemporal dynamics and impacts of coral diseases on individual colonies and coral communities than surveys or visual estimates of disease progression alone.

Transmission of Desulfovibrio salexigens DSM2638 bacteria in Pachyseris involuta-infection rate and changes in coral morphology at different temperatures

Desulfovibrio salexigens is one of the bacteria that infect corals with black band disease (BBD). These bacteria develop fast and cause damage to corals. Therefore, there is a monitor disease transmissinon, especially BBD, in healthy corals to determine the extent to which pathogens can infect coral tissue and the impact of these bacteria on infected coral populations. This study was conducted at the Marine Station Laboratory on Barrang Lompo Island, South Sulawesi, Indonesia. Bacteria were cultured in the Laboratory of Microbiology, Faculty of Medicine, Hasanuddin University. Corals were acclimatised in controlled containers, followed by transmission tests using aquaria (24 units, 45cm×30 cm ×30 cm) filled with 15 litres of sterile seawater. A multifactorial approach was used with treatments comprising different incubation temperature (29°C and 31°C) and different bacterial concentration in the maintenance media (102, 104, and 106 UNIT), as well as the interaction between the effects of temperature and bacterial concentration. Trial parameters were observed every day at intervals of 5 hours. Changes in the appearance diameter of corals infected with pathogenic bacteria were analysed descriptively using underwater photography (Nikon Collfix P7100 camera) and the corals were measured with callipers (precision 0.1 mm). The study concluded that the infection rate of the bacterium D. salexigens strain DSM 2638 in Pachyseris involuta was higher at 31°C-29°C. There was no interaction between the effects of temperature and bacterial concentration on the infection rate of infected coral fragments. Bacterial attack was more severe on Pachyseris involuta fragments maintained at 31°C than at 29°C.

Transcriptome Analyses of Immune System Behaviors in Primary Polyp of Coral Acropora digitifera Exposed to the Bacterial Pathogen Vibrio coralliilyticus under Thermal Loading.

Elevated sea surface temperature associated with global warming is a serious threat to coral reefs. Elevated temperatures directly or indirectly alter the distribution of coral-pathogen interactions and thereby exacerbate infectious coral diseases. The pathogenic bacterium Vibrio coralliilyticus is well-known as a causative agent of infectious coral disease. Rising sea surface temperature promotes the infection of corals by this bacterium, which causes several coral pathologies, such as bacterial bleaching, tissue lysis, and white syndrome. However, the effects of thermal stress on coral immune responses to the pathogen are poorly understood. To delineate the effects of thermal stress on coral immunity, we performed transcriptome analysis of aposymbiotic primary polyps of the reef-building coral Acropora digitifera exposed to V. coralliilyticus under thermal stress conditions. V. coralliilyticus infection of coral that was under thermal stress had negative effects on various molecular processes, including suppression of gene expression related to the innate immune response. In response to the pathogen, the coral mounted various responses including changes in protein metabolism, exosome release delivering signal molecules, extracellular matrix remodeling, and mitochondrial metabolism changes. Based on these results, we provide new insights into innate immunity of A. digitifera against pathogen infection under thermal stress conditions.

Antibacterial activity of acroporid bacterial symbionts against White Patch Disease in Karimunjawa Archipelago, Indonesia

White Patch Disease (WPD), also known as White Pox, is a coral disease common in the Caribbean. Recently, it was observed for the first time in the Karimunjawa Archipelago, Indonesia. The lethal disease is characterized by patchy necrosis found all over the coral colony. We screened and characterized 87 isolates derived from 9 species of healthy coral-associated bacteria for their anti-pathogenic activity against WPD. Forty-nine out of 87 strains inhibited the growth of Halomonas meridiana and Virgibacillus salarius, the WPD associated bacteria isolated from infected Acropora muricata coral. The antipathogenic activity was re-screened using the disc diffusion method. BMT4 and BAF4 isolates displayed the strongest antibacterial activity and thus studied further. Partial sequencing of 16S rDNA showed that BMT4 and BAF4 isolates have a strong relationship with Bacillus flexus strain NBRC15715 and Lysobacter arseniciresistens strain ZS79. In addition, different types of WPD-associated bacteria were investigated. Various bacterial phylotypes of Acropora demonstrated antipathogenic ability thus indicating their potential role as bio-control agents against WPD from the Karimunjawa Archipelago.

Transmission of Desulfovibrio salexigens DSM2638 Bacteria in Pachyseris involuta-Infection Rate and changes in Coral Morphology at different temperatures

Desulfovibrio salexigens is one of the bacteria that infect corals with black band disease (BBD). These bacteria develop fast and cause damage to corals. Therefore, there is a monitor disease transmissinon, especially BBD, in healthy corals to determine the extent to which pathogens can infect coral tissue and the impact of these bacteria on infected coral populations. This study was conducted at the Marine Station Laboratory on Barrang Lompo Island, South Sulawesi, Indonesia. Bacteria were cultured in the Laboratory of Microbiology, Faculty of Medicine, Hasanuddin University. Corals were acclimatised in controlled containers, followed by transmission tests using aquaria (24 units, 45cmx30 cm x30 cm) filled with 15 litres of sterile seawater. A multifactorial approach was used with treatments comprising different incubation temperature (29⁰C and 31⁰C) and different bacterial concentration in the maintenance media (102, 104, and 106 UNIT), as well as the interaction between the effects of temperature and bacterial concentration. Trial parameters were observed every day at intervals of 5 hours. Changes in the appearance diameter of corals infected with pathogenic bacteria were analysed descriptively using underwater photography (Nikon Collfix P7100 camera) and the corals were measured with callipers (precision 0.1 mm). The study concluded that the infection rate of the bacterium D. salexigens strain DSM 2638 in Pachyseris involuta was higher at 31⁰C-29⁰C. There was no interaction between the effects of temperature and bacterial concentration on the infection rate of infected coral fragments. Bacterial attack was more severe on Pachyseris involuta fragments maintained at 31⁰C than at 29⁰C.

Comparative analysis of bacterial communities associated with healthy and diseased corals in the Indonesian sea.

Coral reef ecosystems are impacted by climate change and human activities, such as increasing coastal development, overfishing, sewage and other pollutant discharge, and consequent eutrophication, which triggers increasing incidents of diseases and deterioration of corals worldwide. In this study, bacterial communities associated with four species of corals: Acropora aspera, Acropora formosa, Cyphastrea sp., and Isopora sp. in the healthy and disease stages with different diseases were compared using tagged 16S rRNA sequencing. In total, 59 bacterial phyla, 190 orders, and 307 genera were assigned in coral metagenomes where Proteobacteria and Firmicutes were pre-dominated followed by Bacteroidetes together with Actinobacteria, Fusobacteria, and Lentisphaerae as minor taxa. Principal Coordinates Analysis (PCoA) showed separated clustering of bacterial diversity in healthy and infected groups for individual coral species. Fusibacter was found as the major bacterial genus across all corals. The lower number of Fusibacter was found in A. aspera infected with white band disease and Isopora sp. with white plaque disease, but marked increases of Vibrio and Acrobacter, respectively, were observed. This was in contrast to A. formosa infected by a black band and Cyphastrea sp. infected by yellow blotch diseases which showed an increasing abundance of Fusibacter but a decrease in WH1-8 bacteria. Overall, infection was shown to result in disturbance in the complexity and structure of the associated bacterial microbiomes which can be relevant to the pathogenicity of the microbes associated with infected corals.

Increases and decreases in marine disease reports in an era of global change.

Outbreaks of marine infectious diseases have caused widespread mass mortalities, but the lack of baseline data has precluded evaluating whether disease is increasing or decreasing in the ocean. We use an established literature proxy method from Ward and Lafferty (Ward and Lafferty 2004 PLoS Biology2, e120 (doi:10.1371/journal.pbio.0020120)) to analyse a 44-year global record of normalized disease reports from 1970 to 2013. Major marine hosts are combined into nine taxonomic groups, from seagrasses to marine mammals, to assess disease swings, defined as positive or negative multi-decadal shifts in disease reports across related hosts. Normalized disease reports increased significantly between 1970 and 2013 in corals and urchins, indicating positive disease swings in these environmentally sensitive ectotherms. Coral disease reports in the Caribbean correlated with increasing temperature anomalies, supporting the hypothesis that warming oceans drive infectious coral diseases. Meanwhile, disease risk may also decrease in a changing ocean. Disease reports decreased significantly in fishes and elasmobranchs, which have experienced steep human-induced population declines and diminishing population density that, while concerning, may reduce disease. The increases and decreases in disease reports across the 44-year record transcend short-term fluctuations and regional variation. Our results show that long-term changes in disease reports coincide with recent decades of widespread environmental change in the ocean.