11th ICRS Abstract book - Nova Southeastern University

8-35
Tissue Loss And Tropical Storms: An Investigation Of Bacterial Community
Dynamics in montastraea Annularis Corals in St. Croix, Usvi
Paige ROTHENBERGER* 1,2 , Masoumeh SIKAROODI 3 , Geoffrey COOK 3 , Patrick
GILLEVET 3 , Esther PETERS 3,4 , Robert JONAS 3
1 Division of Coastal Zone Management, U.S. Virgin Islands Department of Planning and
Natural Resources, Frederiksted, Virgin Islands (U.S.), 2 Department of Environmental
Science and Policy, George Mason University, Fairfax, 3 Department of Environmental
Science and Policy, George Mason University, Fairfax, VA, 4 Tetra Tech, Inc., Fairfax
Tissue loss, consistent with white plague type II (WPII), affects at least 18 species of reef
building corals throughout the Caribbean and Western Atlantic. This disease destroys
apparently healthy tissue rapidly thus having the potential to dramatically alter coral
composition on large reef tracts. This investigation examined bacterial communities on
diseased and apparently healthy Montastraea annularis (complex) colonies at Sprat Hole
in St. Croix, U.S. Virgin Islands. Triplicate core samples from multiple pairs of healthy
and diseased colonies were collected in August 2002 and September 2004, immediately
following the passage of Tropical Storm Jeanne to the southwest of St. Croix. Tissue loss
on colonies exhibiting signs of WPII was at epizootic levels at this site during the
summer of 2004. However after the storm only one diseased colony, of five sampled,
appeared to be actively losing tissue. Three of the sampled colonies were accumulating
sediment at the apparent recent disease margin suggesting no active tissue loss, and one
colony had a bleaching margin. Samples were analyzed using microbial culturing,
molecular fingerprinting and partial 16S rRNA gene sequencing. Amplicon Length
Heterogeneity PCR (LH-PCR) fingerprints indicated that bacterial communities differed
significantly between healthy tissue and recently diseased margin samples. There was no
evidence that a specific bacterial taxon dominated any of the tissue types sampled.
Neither cultures nor the amplicon characteristic of Aurantimonas coralicida were found
in any samples, although it might have been present at levels below the method’s limit of
resolution (e.g. 1%). Results of this study highlight the role of local environmental
conditions in the WPII disease process and provide an important description of bacterial
community composition and dynamics in this reef system.
8-36
Heat-Induced Toxin Production in Vibrio Species Associated With Yellow Band Disease
James CERVINO 1,2 , Elizabeth LORENCE* 3 , Fabiano THOMPSON 4 , Konrad HUGHEN 5 ,
Jessie KNEELAND 5 , Garriet SMITH 6
1 Geochemistry, Woods Hole Oceanographic Inst., MA, MA, 2 Biological Sciences, Pace
University, NY, 3 Biological Sciences, Pace University, NY, NY, 4 Department of Genetics,
Federal University of Rio de Janeiro, Ilha do Fundão, Brazil, 5 Geochemistry, Woods Hole
Oceanographic Inst., Woods Hole, MA, 6 Biological Sciences, University of South Carolina,
Aiken, SC
The expression of virulence factors induced from heat stressed yellow band Vibrio pathogens
were investigated by infecting Symbiodinium zooxanthellae CLADES A, B1, C1, and D1
subtypes in vivo. Heat treatments were performed on both the bacteria and the algae at 33C for
three hours. A supernatant was subsequently extracted after centrifugation at 12,000 RPM for 10
minutes. The isolated toxin was then purified using a 2.2 mm millipore filter and re-introduced
to non-heat-treated zooxanthellae CLADE subtype cultures at 26C. Exposure times of 8, 24, 48,
72, 96 and 120hrs to the purified supernatant isolated from the Vibrio bacteria, indicate that the
most severe algal cell necrosis was evident in CLADE subtype C1. However, all heat treated
Symbiodinium in the presence of Vibrio bacteria show severe necrotic cell-death pathways
compared to non-heat treated Symbiodinium. Supernatant toxin was also inoculated onto Aptasia
pallida during high temperature exposure of 33C and low temperature exposure of 26C to
determine the different cell-death mechanisms during toxin exposure. Aptasia pallida death was
detected after exposure to purified toxins at ambient temperatures following 96 hr. However,
when Symbiodinium subtypes were exposed to thermal stress coupled with Vibrio toxin,
morphological and cellular dysfunction occured at 48hr. Cytological analysis and TEM analysis
indicate that the initiation of YBD infection in symbiotic algae may not be exclusively caused
by the weakened state of heat-stressed zooxanthellae. To the contrary, infection seems to be
independent of environmental stress. Rising temperatures also are associated with lesion
advancement that leads to a much faster cell-death in all Symbiodinium CLADE subtypes. In
addition, we found that instead of Symbiodinium being wholly expelled from the gastroderm of
A. pallida, internal cell-death occurs rather than expulsion from the gastrodermal tissues as seen
in thermal coral bleaching.
Oral Mini-Symposium 8: Coral Microbial Interactions
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