11th ICRS Abstract book - Nova Southeastern University

7-13
Black Band Disease (BBD): A Possible Polymicrobial Disease
Orit BARNEAH 1 , Eitan BEN-DOV 1 , Esti KRAMARSKY-WINTER 2 , Yossi LOYA 2 ,
Ariel KUSHMARO* 1
1 Department of Biotechnology Engineering, Ben-Gurion University, Beer-Sheva, Israel,
2 Department of Zoology, Tel-Aviv University, Ramat Aviv, Tel Aviv, Israel
Microbial communities associated with black band disease (BBD) in massive stony
corals from the Northern Red Sea (Eilat) were examined for the first time using
microscopy, microbiological and molecular tools. A high microbial diversity was
revealed in the affected tissue in comparison with the healthy area of the same colony.
Microscopy revealed the penetration of cyanobacteria into the coral mesoglea and
adjacent tissues. Cyanobacterial sequences from Red Sea BBD-affected corals formed a
cluster with sequences previously identified from black band and red band diseased
corals from the Indo-Pacific and Caribbean. In addition, 11 sequences belonging to the
genus Vibrio, a group previously documented as being pathogenic to corals were
retrieved. The distribution and diversity of sulfate-reducing bacteria, a group known to be
associated with BBD and produce toxic sulfide, were studied using specific primers for
the amplification of the dissimilatory sulfite reductase gene (dsrA). This technique
facilitated and improved the resolution of the study of diversity of this group. All the
sequences obtained were closely related to sequences of the genus Desulfovibrio and
46% showed high homology to Desulfovibrio desulfuricans. The complex nature of BBD
and the lack of success in isolating a single causative agent suggest that BBD may be a
polymicrobial disease.
7-14
Black Band Disease Dynamics And Variation in The Pathogenic Microbial
Community
Joshua D. VOSS* 1 , DeEtta K. MILLS 2,3 , Sara E. EDGE 1 , Laurie L. RICHARDSON 2
1 Robertson Coral Reef Program, Harbor Branch Oceanographic Institute at Florida
Atlantic University, Fort Pierce, FL, 2 Biological Sciences, Florida International
University, Miami, FL, 3 International Forensic Research Institute, Florida International
University, Miami
Black band disease (BBD) is a pathogenic microbial assemblage that infects scleractinian
corals on reefs worldwide. After more than thirty years of BBD research, involving
multiple teams and approaches, the microbial composition of this assemblage, the
mechanisms of pathogenicity, and the environmental conditions that promote infection
remain elusive. A growing number of published studies report differences in the
microorganisms that comprise BBD assemblages. While some biogeographic trends
have emerged, relatively small sample sizes and differences in methodologies limit the
inferences that can be made from these divergent data sets. This study utilized length
heterogeneity polymerase chain reaction (LH-PCR) to provide robust, reproducible, and
efficient profiling of BBD microbial communities from various sites in the Caribbean.
LH-PCR differentiates organisms based on natural variation in the 16S rRNA gene and
allows more rapid comparisons of community structure among multiple samples as
compared to cloning and sequencing approaches, albeit with the associated limitation of
discriminating taxa more broadly. The goal of this study was to assess patterns of
variation in BBD microbial assemblages with respect to geographic location, host
species, and time. Multivariate ordination and nonparametric analyses of the LH-PCR
profiles revealed significantly distinct BBD microbial communities sampled from
different geographic regions of the Caribbean. Although significant variation also exists
between BBD infections on different coral species, geographic location appears to more
strongly influence microbial community structure than host species. Despite minor
temporal community variations within individual BBD infections, significant differences
between regions persist. Together with findings of previous and ongoing molecular
analyses of BBD bacterial communities, these results evidence the intrinsic complexity of
this dynamic microbial assemblage.
Oral Mini-Symposium 7: Diseases on Coral Reefs
7-15
The Origin Of Aspergillus Sydowii, An Opportunistic Pathogen Of Caribbean
Gorgonian Corals
Krystal RYPIEN* 1 , Jason ANDRAS 1 , Ginger GARRISON 2 , C. Drew HARVELL 1
1 2
Cornell University, Ithaca, NY, USGS Center for Coastal & Watershed Studies, St.
Petersburg, FL
Coral reefs are increasingly suffering outbreaks of disease, causing dramatic declines in
population abundance and diversity. One of the best-characterized coral diseases is
aspergillosis, caused by the fungus Aspergillus sydowii. A. sydowii is a globally distributed
saprophyte commonly found in soil, so its presence in marine systems raises questions about its
origin. Using microsatellite markers, I analyzed the population structure of A. sydowii from
diseased sea fans, diseased humans, and environmental sources worldwide. The results indicate
that A. sydowii forms a single global population, with low to moderate differentiation between
isolates from sea fans and those from environmental sources. Past researchers have suggested
that A. sydowii originates from African dust blown into the Caribbean, and have identified
Aspergillus from dust samples, although only to the genus level. To test this hypothesis, I
isolated fungi from dust samples collected in Mali and St. Croix. Although a diversity of fungi
were documented from African dust, including seven species of Aspergillus, none of the
samples contained A. sydowii. Taken in conjunction with recent molecular evidence suggesting
lack of a single point source of the fungus, these data indicate that there are likely multiple
sources and introductions of this pathogen into marine systems.
7-16
Fungi in Healthy And Diseased Sea Fans (Gorgonia Ventalina):
Carlos TOLEDO-HERNÁNDEZ* 1 , Adelmari BONES-GONZÁLEZ 1 , José RODRIGUEZ 1 ,
Anabella ZULUAGA-MONTERO 1 , Alberto SABAT 1 , Paul BAYMAN 1
1 Biology Department, University of Puerto Rico, San Juan, Puerto Rico
The coral disease literature has mostly focused on identifying causative agents. However, lack
of knowledge of microbes associated to healthy corals has undermined the ability to understand
the changes in composition of microbes and their roles when colonies become diseased. This
study addresses the following questions. Is the fungal community of healthy Gorgonia ventalina
colonies different in diversity and composition than that of diseased ones? Within colonies with
aspergillosis, does the fungal community of healthy tissue differ from that of diseased tissue? Is
A. sydowii part of the resident mycoflora of healthy sea fans? Can aspergillosis also be caused
by other species of Aspergillus, or by a consortium of fungi? Fungi were isolated from healthy
and diseased fans found in 15 reefs around Puerto Rico, and identified morphologically and by
DNA sequencing (the nuclear ribosomal ITS region) and BLAST searches in GenBank. Fungal
community of healthy fans is distinct and more diverse from diseased one, and within diseased
fans, fungi from diseased tissue is distinct and more diverse than from healthy tissue. Three
mechanisms may explain these results: host immune depression allows pathogens to increase
outcompiting other microbes; environmental factors favor some microbes over others; shift in
diversity is not a cause but a consequence. An unexpected result was that A. sydowii was found
in healthy sea fans and never in diseased one. A possible explanation is that the strains found in
healthy fans were not pathogenic. Or others fungi may be causing the diseases since no a single
fungus was consistently associated with diseased colonies. Given that it is not clear that
Aspergillus is the sole pathogen, calling this disease aspergillosis is an oversimplification at
best.
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