coral disease

Abstract: 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

Abstract

Coral reefsare experiencing large scale degradation. Motivated by the need for regular data monitoring and forquantification of the state and change of benthic and pelagic organisms,the Global Coral Reef Monitoring Networkprotocolwas executed on 18 dive sites in fished and unfished areasaround the island of Saba in the Saba National Marine Park (SNMP) in the Dutch Caribbean from March to May 2019. Pictures of the benthos were taken andanalysed with the Coral Point Count Excel extension software and fish biomass was calculated through the Bayesian length-weight-relationship. Although considerablybelow the Caribbean-wide average, coral cover around the island seems to be slowlyrecoveringfrom past diseasesand hurricane events. Coral species richnesspositively correlates with reef fish density and Serranidae species richness. As in other parts of the Caribbean, macroalgae in the SNMP arerapidly spreadingand increasingly competefor space with habitat-providing gorgonians, sponges and other benthic organisms. Incontrast toexpectations, fish density and biomass continue to increase, evenin zones where fishing is allowed. This mightbe explained by the higher availability of macroalgae that serve as food for variousherbivorous fish species, which in turn are, amongst others, the prey of predatory fish and thosehigher up in the trophic cascade. However, with the exception ofthe commercially important fish family Lutjanidae all key fish species have declinedin average size in recent years. Another findingis the increase of coral diseases. The results indicate the need for further species-specific research in order to identify the factorsthat arecausing the degradation ofthe reefs in the SNMP. A better understandingofthe interactions, ecological roles and functions of benthic and fish communities is therefore essential for the protection of reefs, that are of high value to Saba. The results of this study contribute to the adaptive management of the Saba Conservation Foundation that manages the SNMP.

Keywords: GCRMN, Reef Health Index, marine protected area, fish-benthos interaction, macroalgae, herbivory, trophic cascade, fishing, coral disease, Caribbean

Disease outbreaks have been involved in the deterioration of coral reefs worldwide and have been par- ticularly striking among crustose coralline algae (CCA). Although CCA represent important cues for coral settle- ment, the impact of CCA diseases on the survival and settlement of coral planulae is unknown. Exposing coral larvae to healthy, diseased, and recently dead crusts from three important CCA species, we show a negative effect of disease in the inductive CCA species Hydrolithon boergesenii on larval survivorship of Orbicella faveolata and settlement of O. faveolata and Diploria labyrinthi- formis on the CCA surface. No effect was found with the less inductive CCA species Neogoniolithon mamillare and Paragoniolithon accretum. Additionally, a majority of planulae that settled on top of diseased H. boergesenii crusts were on healthy rather than diseased/dying tissue. Our experiments suggest that CCA diseases have the po- tential to reduce the survivorship and settlement of coral planulae on coral reefs. 

In the 1970s, black band disease (BBD) emerged as a mass coral killer and caught the attention of scientists. Although BBD has been studied for more than thirty years, it continues to confound scientists due to the complexity and composition of the bacterial mat which varies among BBD cases. In previous studies, BBD was found in correlation with small environmental changes. Because the distribution of BBD has not been previously documented for Bonaire, I studied its distribution and measured environmental parameters (depth, temperature, pH, phosphate and nitrogen) at six sites. I also recorded the number of BBD incidents on 3 replicate transects, each 10 m 2 in area and 10 m apart at both 15 and 30 feet. BBD was found at Andrea II (both depths), Angel City (both depths) and Jeannie’s Glory (15 ft), but not at Karpata, Captain Don’s, or Yellow Submarine. Informal surveys at other dive sites on Bonaire and Klein Bonaire showed BBD cases at Monk’s Haven, Monte’s Divi, and Handsoff reef, but it was not present at Boca Bartol or Nukove. Most BBD cases were found shallower than 20 feet. I found no statistically significant differences between environmental parameters and observed BBD cases.

This student research was retrieved from Physis: Journal of Marine Science I (Fall 2006)19: 26-32 from CIEE Bonaire.

Coral reefs worldwide are currently jeopardized by anthropogenic factors such as land-based pollution, coastal development, and sediment erosion. In the Caribbean alone, nearly two-thirds of coral reefs have been deemed as threatened. This study investigated the potential negative effects of water quality and eutrophication, Enterococci bacteria (found in human gut), and sedimentation on coral disease, bleaching, and macroalgal growth on the near shore reefs of Bonaire, N.A. Monitoring sites were defined according to their proximity to anthropogenic activity: “more impacted” or “less impacted” (< 200 m and > 200 m from coastal development, respectively). Water samples at 5 m were collected weekly and at 12 m biweekly from each site and tested for nutrient concentrations (NO3, NO2 - , NH4-N, PO4), Most Probable Number of Enterococci bacteria, sedimentation rates, and particle size distributions. Video transects (100 m) were also taken at defined depths and analyzed for live coral cover and diversity, percent disease and bleaching, and macroalgal cover. Data showed elevated NH4-N levels at all sites, Enterococci bacteria present at 3 of the 4 sites (mainly at 5 m), and sediment particle counts showed significant differences among sizes at both depths and between the interaction of size and impact at 12 m. There was also a strong trend of finer grained sediments at high impact sites and coarser grained sediments at low impact sites. Very little overall coral disease (1.105 ± 1.563 % at more impacted sites and 0.400 ± 0.566 % at less impacted sites in 12 m) and bleaching (3.245 ± 0.615 % at more impacted sites and 1.390 ± 1.966 % at less impacted sites in 12 m) was found on the reefs however, neither were present at 5 m. There was significantly more macroalgae at 12 m and a strong trend of more macroalgae at the deeper, more impacted sites. This study suggests that increased anthropogenic activity on Bonaire is contributing to the increased NH4- N levels, Enterococci bacteria presence, and finer particle sediments, which future studies may correlate significant interactions between these parameters and coral disease, bleaching, and macroalgal growth.

This student research was retrieved from Physis: Journal of Marine Science VI (Fall 2009)19: 35-43 from CIEE Bonaire.

Anthropogenically induced stressors are degrading coral reefs globally. Nutrients and bacteria present in wastewater increase the frequency and severity of coral disease. As a result of the lack of sewage treatment and poor sewage containment in Bonaire, N.A., the surrounding coastal marine environment is likely the endpoint of sewage-contaminated groundwater, especially near resort areas where water use is high and only a small portion of sewage is trucked away. This study compared the frequency of coral disease at three sites adjacent to resorts (with >100 beds) with three sites in the same region of the leeward coast that are not adjacent to resorts. Because areas where groundwater is entering the near-shore environment have not been identified; physical parameters of the seawater (temperature, specific conductivity, dissolved oxygen, and pH) at the six sites were measured using a YSI multiparameter probe held directly above the substrate in areas 100 m wide along depths of 3, 6, 9, 12, and 18 m. To detect the presence of enterococci, a fecal indicator bacteria, six water samples were collected at 3, 9, and 18 m isobaths, 0.5 m below the surface and above the substrate. Additionally, water samples were collected twice at 3, 6, 9, 12, and 18 m to determine ammonia concentrations at each site. To determine the frequencies of disease in hard coral (≥20 cm) and soft corals (sea fans, sea rods, sea plumes), three 10 x 1 m transects were surveyed at 3, 6, 9, and 18 m at all sites. The relationship between depth and specific conductivity, temperature, dissolved oxygen, and pH were similar for all sites except 18th Palm. Significantly higher concentrations of ammonia were found at resort sites (p=0.016). Enterococci was detected at the three resort sites in greater concentrations than at non-resort sites. Disease in hard and soft corals did not differ between site types. This study suggests that coral reefs adjacent to resorts have greater concentrations of ammonia and enterococci, common wastewater indicators. Although the frequencies of soft and hard coral disease were not significant between sites, the abundance of hard corals was significantly lower at resort than at nonresort sites (p=0.010). Soft corals were less abundant at resort sites than at non-resort sites, but the difference was not statistically significant (p=0.059).

This student research was retrieved from Physis: Journal of Marine Science VII (Spring 2010)19: 1-11 from CIEE Bonaire.

Trying to understand the extent to which anthropogenic stressors impact coral reefs globally has led to an increase in studies which analyze the effects of nutrient enrichment on the frequency and severity of coral disease. Bonaire, Dutch Caribbean currently has no sewage treatment facility in place, resulting in the percolation of wastewater to the surrounding coastal marine environment. On the reefs near resorts, there is a large volume of groundwater used and subsequently discharged into the ocean. As a result, the reefs directly in front of major resorts are likely to have higher disease levels than reefs without resorts nearby. The goal of this study was to evaluate the difference in prevalence of coral disease between sites located in close proximity to groundwater discharge and sites located further away. In order to achieve this objective, six sites with varying gradients of exposure to sewage discharge were surveyed by laying down 1 m x 30 m transect belts parallel to the shore at 6 m, 12 m and 18 m depths. During each survey, nutrient enrichment, macroalgal cover, water depth and coral colonies displaying signs of disease were recorded. Water quality was assessed using a number of parameters including nutrients (ammonium, ammonia, phosphate and dissolved oxygen), Enterococci bacteria and sedimentation. At sites closer to resorts there were higher nutrient levels and percent cover macroalgae, however sedimentation rates and mean percent coral disease frequency were highest at medium impacted sites. Low impacted sites had a greater presence of coral disease at shallower depths, compared to high impacted sites. This data will be used to illustrate a relationship between coral disease and anthropogenic stressors and provide a baseline for future studies.

This student research was retrieved from Physis: Journal of Marine Science IX (Spring 2011)19: 1-11 from CIEE Bonaire.

Coral reefs have existed for thousands of years and are currently subjected to many threats. Coral disease is of particular concern because of its increasing prevalence; because they reduce coral cover, diseases are likely to affect fish assemblages. This study looks at the factors of coral disease and fish species richness on Bonaire, Dutch Caribbean. The study tests the hypotheses that (1) the amount of coral disease present in Bonaire has increased since 2007 and (2) the species richness of fish assemblages decreases with increasing presence of coral disease. Coral disease prevalence and live coral cover was assessed using an adaptation of the AGRRA benthic methodology by laying 10 m transects at depths of 10 and 12.5 m at Cliff and Windsock, areas that are closed and opened to fishing respectively. In addition, fish species richness was assessed using the roving diver technique by REEF. There was a significant difference between coral disease, as well as live coral cover, between sites and years. Species richness had a significant weak but not significant correlation with coral disease and live coral cover. However, no significant difference was found in the fish species richness between sites or between years.

This student research was retrieved from Physis: Journal of Marine Science X (Fall 2011)19: 40-46 from CIEE Bonaire.

Sponges are important to reef health, fulfilling a number of structural and functional roles. Despite the wide range of functions they provide, limited research on sponges has been conducted. Their ability to filter the water column of nutrients is essential to keeping the water around reefs clean. Coral reef diseases are becoming more widespread due to multiple factors such as pollution and eutrophication. This study assessed the possible relationship between sponge abundance and disease prevalence in Bonaire, Dutch Caribbean, by using 10 m x 2 m belt transects photographed into 1 m x 1 m quadrats. Per transect, 10 randomly selected photographs were analyzed using Image J to find the total area of sponges and live and diseased coral. Less than 1% disease was found at the study sites because the majority of the coral in the quadrats was partially or completely dead. No correlation was found between disease and sponge coverage. However, a significant correlation was found between percent sponges and live coral coverage. Although there was no correlation found between sponge cover and disease prevalence, the relationship between live coral and sponge is of particular importance for reef health monitoring across the Caribbean.

This student research was retrieved from Physis: Journal of Marine Science X (Fall 2011)19: 35-39 from CIEE Bonaire.

Coral reefs are one of the most diverse ecosystems found on earth, and are home to many habitat-specific fish. The Gobiidae family is known to be one of the most habitat-specific groups. Two common gobies found in the Caribbean are Coryphopterus lipernes and Gobiosoma evelynae, and both species rest on live coral heads. This study was conducted to determine if C. lipernes and G. evelynae show a preference for certain coral species and if the presence of disease affects this selection. A benthic survey was performed using video transects and CPC data analysis, allowing calculation of percent frequency for each coral species and frequency of diseased corals. Goby searches were conducted using SCUBA within a depth range of 10 - 15 m along the reef, recording the coral of choice and its disease status. The results showed that C. lipernes selected for 3 coral species and against 5, favoring Colpophyllia natans and Montastraea cavernosa. G. evelynae selected for 3 coral species and against 5, favoring M. cavernosa and Stephanocoenia spp. Both goby species selected significantly against coral disease, C. lipernes had a mean disease selection ratio of 0.39, and G. evelynae showed a complete selection against disease. Coral reefs are important ecosystems that are currently under significant abiotic and biotic stressors. It is important to understand the influence that an increase in disease and reduction in coral abundance may have on habitat-specific fish.

This student research was retrieved from Physis: Journal of Marine Science XI (Fall 2012)19: 96-102 from CIEE Bonaire.