Diseased Sea Fans Research Articles

Comparison of chemical compounds associated with sclerites from healthy and diseased sea fan corals (Gorgonia ventalina).

BackgroundThe roles of gorgonian sclerites as structural components and predator deterrents have been widely studied. Yet their role as barriers against microbes has only recently been investigated, and even less is known about the diversity and roles of the chemical compounds associated with sclerites.MethodsHere, we examine the semi-volatile organic compound fraction (SVOCs) associated with sclerites from healthy and diseased Gorgonia ventalina sea fan corals to understand their possible role as a stress response or in defense of infection. We also measured the oxidative potential of compounds from diseased and healthy G. ventalina colonies.ResultsThe results showed that sclerites harbor a great diversity of SVOCs. Overall, 70 compounds were identified, the majority of which are novel with unknown biological roles. The majority of SVOCs identified exhibit multiple immune-related roles including antimicrobial and radical scavenging functions. The free radical activity assays further confirmed the anti-oxidative potential of some these compounds. The anti-oxidative activity was, nonetheless, similar across sclerites regardless of the health condition of the colony, although sclerites from diseased sea fans display slightly higher anti-oxidative activity than the healthy ones.DiscussionSclerites harbor great SVOCs diversity, the majority of which are novel to sea fans or any other corals. Yet the scientific literature consulted showed that the roles of compounds found in sclerites vary from antioxidant to antimicrobial compounds. However, this study fell short in determine the origin of the SVOCs identified, undermining our capacity to determine the biological roles of the SVOCs on sclerites and sea fans.

Spatial variation in fungal communities isolated from healthy and diseased sea fans Gorgonia ventalina and seawater

Sea fans Gorgonia ventalina in the Caribbean are being infected by disease attributed to the fungus Aspergillus sydowii. Little is known about the natural fungal community in sea fans, including spatial variation in community composition and the source of inoculum. Patterns of spatial variation may provide important clues to the source of pathogens and etiology of the disease. The objectives of this study were: (1) to measure spatial variation in the mycoflora associated with dis- eased and healthy colonies of G. ventalina; and (2) to compare the mycoflora of sea fans with the mycoflora isolated from surrounding seawater. Samples of diseased and healthy sea fan tissue and seawater were collected from coral reefs in Puerto Rico. Fungi were isolated and identified by morphology and sequencing of the nuclear ribosomal internal transcribed spacer region. Twenty-six species of fungi were identified. A. flavus was the most common species isolated from both seawater and sea fan tissue. Higher species richness was found in seawater than in sea fans. Mycoflora of healthy and diseased sea fans differed among sites. Fungal species richness in seawater was higher nearshore than offshore. However, community composition in seawater did not vary spatially. The fungal community of sea fans was not different from that of the surrounding seawater, suggesting low specificity. Our data suggest that the source of offshore mycoflora is the nearshore fungal community, with richness diluted as a result of ocean circulation. Prevalence of aspergillosis was not correlated with fungal species richness but was positively correlated with the number of fungal strains isolated. The fact that diseased fans did not have lower species richness suggests that the disease is not due to a single pathogen, but rather to a variety of opportunistic pathogens.

Nitrogen source preference of Aspergillus sydowii, an infective agent associated with aspergillosis of sea fan corals

We attempt to identify the mechanism by which nitrogen enrichment increases the prevalence of aspergillosis, a disease caused by the terrestrial fungus Aspergillus sydowii, which infects sea fan corals (Gorgonia ventalina) throughout the Caribbean, by looking at the metabolic capabilities of the pathogen to (1) determine whether A. sydowii can catabolize sea fan‐derived nitrogen, (2) ascertain fungal preference for different nitrogen sources, and (3) determine whether fungi isolated from diseased sea fans preferentially assimilate sea fan‐derived nitrogen. Stable nitrogen isotope experiments demonstrated that A. sydowii is capable of assimilating and prefers sea fan‐ derived nitrogen (72% of available nitrogen) to nitrate and more readily assimilates nitrogen from coral tissue than gorgonin skeleton. Variation in the proportion of sea fan‐derived nitrogen assimilated by different fungal isolates was significant, with those from diseased sea fans showing greater nitrogen assimilation of sea fan tissue.

Fungi in healthy and diseased sea fans (Gorgonia ventalina): is Aspergillus sydowii always the pathogen?

Caribbean corals, including sea fans (Gorgonia spp.), are being affected by severe and apparently new diseases. In the case of sea fans, the pathogen is reported to be the fungus Aspergillus sydowii, and the disease is named aspergillosis. In order to understand coral diseases and pathogens, knowledge of the microbes associated with healthy corals is also necessary. In this study the fungal community of healthy Gorgonia ventalina colonies was contrasted with that of diseased colonies. In addition, the fungal community of healthy and diseased tissue within colonies with aspergillosis was contrasted. Fungi were isolated from healthy and diseased fans from 15 reefs around Puerto Rico, and identified by sequencing the nuclear ribosomal ITS region and by morphology. Thirty fungal species belonging to 15 genera were isolated from 203 G. ventalina colonies. Penicillum and Aspergillus were the most common genera isolated from both healthy and diseased fans. However, the fungal community of healthy fans was distinct and more diverse than that of diseased ones. Within diseased fans, fungal communities from diseased tissues were distinct and more diverse than from healthy tissue. The reduction of fungi in diseased colonies may occur prior to infection due to environmental changes affecting the host, or after infection due to increase in dominance of the pathogen, or because of host responses to infection. Data also indicate that the fungal community of an entire sea fan colony is affected even when only a small portion of the colony suffers from aspergillosis. An unexpected result was that A. sydowii was found in healthy sea fans but never in diseased ones. This result suggests that A. sydowii is not the pathogen causing aspergillosis in the studied colonies, and suggests several fungi common to healthy and diseased colonies as opportunistic pathogens. Given that it is not clear that Aspergillus is the sole pathogen, calling this disease aspergillosis is an oversimplification at best.

Isolation and characterization of microsatellite loci in Aspergillus sydowii, a pathogen of Caribbean sea fan corals

Here we report on nine microsatellite loci designed for Aspergillus sydowii, a widely distributed soil saprobe that is also the pathogenic agent of aspergillosis in Caribbean sea fan corals. Primers were tested on 20 A. sydowii isolates from the Caribbean, 17 from diseased sea fans and three from environmental sources. All loci were polymorphic and exhibited varying degrees of allelic diversity (three to nine alleles). Gene diversity (expected heterozygosity) ranged from 0.353 to 0.821. These primers will enable future research into the epidemiology of A. sydowii as an emergent infectious disease.

Longitudinal study of aspergillosis in sea fan corals

Aspergillosis (a fungal disease) is affecting sea fan corals Gorgonia spp. throughout the Caribbean. To measure the impact of this disease, we established longitudinal, or in other words individual-based, monitoring studies on 3 reefs in the Florida Keys, USA, to obtain estimates of incidence, rates of disease progress, recovery, and mortality. At Western Dry Rocks (near Key West), 40 Gorgonia ventalina colonies (20 initially healthy and 20 initially diseased) were photo-monitored between June 1996 and May 1998. Additional sea fans were visually monitored during 2 localized outbreaks at Conch (May 1998 to September 1999) and Carysfort (July 2000 to May 2001) reefs located in the Upper Keys. Data from Western Dry Rocks showed that over a 2 yr period, the incidence rate was 0.58 sea fans yr(-1) and that tissue purpling can lead to tissue loss and subsequently to mortality, albeit at low frequencies. Most sea fans, once infected, maintained a low level of damage over time. Only 3 fans recovered from the disease; however 2 were subsequently re-infected. Case fatality rate was 10% (2 of 20 initially infected died), which is equivalent to 5% yr(-1). However, mortality can increase during localized outbreaks. At Conch, mortality was 46% yr(-1) among infected sea fans (compared to 8% yr(-1) at Carysfort, a less impacted site, during the same period). During an outbreak at Carysfort, mortality was 95% yr(-1) among diseased sea fans. These data clearly demonstrate the significant role aspergillosis plays in the population ecology of sea fan corals.

The Relationship Between Gorgonian Coral (Cnidaria: Gorgonacea) Diseases and African Dust Storms

The number of reports of coral diseases has increased throughout the world in the last 20 years. Aspergillosis, which primarily affects Gorgonia ventalina and G. flabellum, is one of the few diseases to be characterized. This disease is caused by Aspergillus sydowii, a terrestrial fungus with a worldwide distribution. Upon infection, colonies may lose tissue, and ultimately, mortality may occur if the infection is not sequestered. The spores of A. sydowii are <5 μm, small enough to be easily picked up by winds and dispersed over great distances. Aspergillosis is prevalent in the Caribbean, and it appears that this primarily terrestrial fungus has adapted to a marine environment. It has been proposed that dust storms originating in Africa may be one way in which potential coral pathogens are distributed and deposited into the marine environments of the Caribbean. To test the hypothesis that African dust storms transport and deposit pathogens, we collected air samples from both dust storms and periods of non-dust in St. John, U.S. Virgin Islands. Because we focused on fungal pathogens and used A. sydowii as a model, we isolated and cultured fungi on various types of media. Fungi including Aspergillus spp. were isolated from air samples taken from dust events and non-dust events. Twenty-three separate cultures and seven genera were isolated from dust event samples whereas eight cultures from five genera were isolated from non-dust air samples. Three isolates from the Virgin Islands dust event samples morphologically identified as Aspergillus spp. produced signs of aspergillosis in seafans, and the original pathogens were re-isolated from those diseased seafans fulfilling Koch's Postulates. This research supports the hypothesis that African dust storms transport across the Atlantic Ocean and deposit potential coral pathogens in the Caribbean.

Cause of sea fan death in the West Indies

A fungus from the genus Aspergillus is the probable agent of epizootic infections that have caused mass mortality of sea fan corals (Gorgonia ventalina) over the past 15 years1,2. Here we show that four strains of the fungus involved in these infections are members of the species Aspergillus sydowii, a common saprobe (an organism that lives on decaying matter) that is found in both terrestrial and marine environments. Isolates of A. sydowii taken from diseased sea fans caused new infections of sea fans in inoculation experiments, whereas isolates taken from elsewhere did not.

Widespread disease in Caribbean sea fans:II. Patterns of infection and tissue loss

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 160:255-263 (1997) - doi:10.3354/meps160255 Widespread disease in Caribbean sea fans: II. Patterns of infection and tissue loss I. Nagelkerken1,*, K. Buchan2, G. W. Smith3,4, K. Bonair5, P. Bush6, J. Garzón-Ferreira7, L. Botero7, P. Gayle8, C. D. Harvell9, C. Heberer10, K. Kim9, C. Petrovic11, L. Pors1, P. Yoshioka10 1Carmabi Foundation, PO Box 2090, Piscaderabaai z/n, Curaçao, Netherlands Antilles 2Saba Marine Park, Fort Bay, PO Box 18, The Bottom, Saba, Netherlands Antilles 3Department of Biology, University of South Carolina -Aiken, 171 University Parkway, Aiken, South Carolina 29801, USA 4Bahamian Field Station, PO Box 2488, Port Charlotte, Florida 33949, USA 5Institute of Marine Affairs, Hilltop Lane, Chaguaramas, PO Box 3160, Carenage Post Office, Trinidad and Tobago, West Indies 6Cayman Islands Natural Resources Unit, PO Box 486, George Town, Grand Cayman, British West Indies 7Instituto de Investigaciones Marinas y Costeras, INVEMAR, Apartado 1016, Santa Marta, Colombia 8Discovery Bay Marine Lab, PO Box 35, Discovery Bay, St. Ann, Jamaica 9Section of Ecology and Systematics, Cornell University, Ithaca, New York 14853, USA 10Department of Marine Sciences, University of Puerto Rico, Mayagüez Campus, PO Box 5000, Mayagüez, Puerto Rico 11H. Lavity Stoutt Community College, Paraquita Bay Campus, PO Box 3097, Road Town, Tortola, British Virgin Islands *E-mail: inagelk@ibm.net Large lesions and widespread tissue loss in the sea fans Gorgonia ventalina and G. flabellum L. occurred throughout most of the Caribbean during 1995 and 1996. An earlier study identified the putative pathogen as a fungus in the genus Aspergillus (Smith et al. 1996). Repeated surveys showed that in the Bahamas the incidence (= % of diseased sea fans) and virulence (= % tissue loss per diseased colony) of the disease increased rapidly from 1995 to 1996. Repeated surveys in Curaçao and Saba showed little variation in incidence and virulence. Incidence of the disease was higher on larger than on smaller colonies. On sheltered or moderately exposed shallow reefs (<12 m), both incidence and virulence were positively correlated with water depth. The number of lesions on diseased sea fans, measured only in Curaçao, also increased with depth. These patterns may result from a decrease in wave action, which usually declines with water depth, and the consequent reduction in the swaying motion of the sea fans, thus affecting success of pathogen attachment and establishment. The sea fan predator snail Cyphoma gibbosum was more abundant on diseased than on healthy colonies but its density appears to have been too low to contribute significantly to infection and tissue loss. Algal tumors were found on both healthy and diseased colonies and showed no clear association with the disease. Disease · Fungal pathogen · Aspergillus · Tissue loss · Mortality · Sea fan · Gorgonia ventalina · Gorgonia flabellum · Cyphoma gibbosum · Algal tumors Full text in pdf format PreviousNextExport citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 160. Publication date: December 15, 1997 Print ISSN:0171-8630; Online ISSN:1616-1599 Copyright © 1997 Inter-Research.