11th ICRS Abstract book - Nova Southeastern University

8-9
Milkfish Feces Share Common Bacteria With Coral Holobiont
Steven SMRIGA* 1,2 , Melissa GARREN 1,2 , Farooq AZAM 1
1 Marine Biology Research Division, Scripps Institution of Oceanography, La Jolla, CA,
2 Marine Biology Research Division, Scripps Institution of Oceanography, La Jolla
Effluent from intensive milkfish (Chanos chanos) aquaculture is among several
environmental stressors that may impact coral reefs near Bolinao, Pangasinan,
Philippines. Fish feces are part of this effluent, and since the effects of effluents on coralassociated
microbial communities may provide a mechanistic link between fish farms and
coral reefs, it is of interest to consider the potential effects of fish feces on corals. We
hypothesized that distinct bacterial groups found in fish feces can also be found on corals.
Feces were collected from the distal intestines of milkfish, bacterial isolates were
obtained from water samples, and coral tissue slurries were collected from diverse coral
genera along a quantifiable gradient of effluent. Community 16S rDNA gene profiles
from feces were dominated by Vibrio sp., while profiles from each of four coral samples
were considerably more diverse. Despite these differences, some 16S rDNA genes from
feces and corals were >99% similar including Ralstonia sp. and Acinetobacter sp..
Furthermore, some Vibrio sp. sequences were >99% similar among feces, corals, and
isolated bacteria. The findings suggest that among these diverse sample types, specific
microenvironments may select for the same microbial phylotypes. Alternatively, fish
feces may select for specific microbial phylotypes that are then transported into coral
ecosystems via water effluents and introduced into the coral holobiont. Fish feces should
be considered within conceptual and experimental approaches that address coralmicrobial
interactions, including those that address coral disease.
8-10
Functional Change in Microbial Communities On Four Coral Atolls
Elizabeth DINSDALE* 1 , Olga PANTOS 2 , Robert EDWARDS 3 , Steven SMRIGA 4 ,
Florent ANGLY 3 , Dana HALL 3 , Linda WEGLEY 3 , Enric SALA 4 , Stuart SANDIN 4 ,
Rebecca VEGA THURBER 3 , Bette WILLIS 5 , Farooq AZAM 4 , Nancy KNOWLTON 4 ,
Forest ROHWER 3
1 Biology Department, San Diego State University, San Diego, CA, 2 University of
Queensland, Brisbane, Australia, 3 San Diego State University, San Diego, CA, 4 Scripps
Institution of Oceanography, San Diego, CA, 5 James Cook University, Townsville,
Australia
Replacement of corals by algae is a reoccurring trend on today’s coral reefs. The role of
microbes in these phase shifts is unknown. Microbial communities were quantified in the
water column across four coral atolls displaying different levels of coral cover, using
metagenomic, microscopic, and culturing techniques. A 10-fold increase in abundance of
virus-like particles, Bacteria, and Archaea and a doubling of the number of protists in the
overlying waters occurred from the coral reefs with the highest coral cover to the coral
reefs with the lowest coral cover. The metagenomic taxonomic analysis showed that
Bacteria and Archaea changed from a balanced community of autotrophs and
heterotrophs to a predominantly heterotrophic community where coral cover was low. On
the coral reefs with the lowest coral cover the heterotrophic microbes were dominated by
potentially pathogenic strains. The relative proportions of the functional genes on each
atoll confirmed the non-linear change in the microbial community. On the coral reef with
the highest coral cover, the proportion of genes associated with photosynthesis was 3.4
%; they increased to 44.3 % on the coral reef with a moderate coral cover; and decreased
to only 0.3 % on the reef with the lowest coral cover. In contrast, genes associated with
carbon utilization comprised 24 % on the impacted reef. Where coral cover was high,
microbial numbers were low and metabolically providing a diverse range of functions,
including photosynthesis and nutrient recycling. Conversely, where coral cover was low,
microbial numbers were high and restricted to functions that focused on consuming
carbon and nutrients. Corals that remain alive on algae dominated reefs are bathed in
water that contains high numbers of heterotrophic microbes. Not surprisingly the health
of many of these remaining corals was compromised.
Oral Mini-Symposium 8: Coral Microbial Interactions
8-11
Exploring Bacterial Community Dynamics in Early Life Stages Of The Caribbean Corals
porites Astreoides And montastrea Faveolata
Koty SHARP* 1
1 Smithsonian Marine Station, Fort Pierce, FL
Like other marine invertebrates, scleractinian corals have been shown to harbor diverse
assemblages of microbes, but neither the specificity of these associations nor the mechanisms
that maintain them across host generations is well understood. Bacterial communities in
planula larvae of the Caribbean coral Porites astreoides were characterized in this study.
Molecular techniques were used to identify bacteria associated with P. astreoides larvae, and
sequence-specific oligonucleotide primers were designed to survey multiple samples for the
presence of particular bacterial species. Fluorescence in situ hybridization (FISH) and
microscopy revealed the presence of particular localizations of specific bacteria within the
larvae, and the relative abundance of various groups of bacteria in the larvae was estimated. In
contrast, gamete bundles from the mass-spawning corals Montastrea spp. and Acropora spp.
did not contain bacteria or archaea. Molecular analysis on post-settlement stages of M.
faveolata was used to characterize the bacterial communities present in juvenile feeding polyps.
This study reveals new insights into mechanisms by which microbial assemblages associated
with corals are maintained and regulated during host embryogenesis and early development. In
addition, these results present the possibility for a bacterial role in larval ecology of some coral
species.
8-12
Dom Assimilation By A Coral Reef Sponge And Its Associated Prokaryotes: A Carbon
Isotope Tracer Study
Jasper DE GOEIJ 1,2 , Leon MOODLEY 3 , Nestor CARBALLEIRA 4 , Fleur VAN DUYL* 1,5
1 Royal Netherlands Institute for Sea Research, Den Burg, Netherlands, 2 The Carmabi
Foundation, Curacao, Netherlands Antilles, 3 Netherlands Institute of Ecology, Yerseke,
Netherlands, 4 University of Puerto Rico, San Juan, Puerto Rico, 5 Royal Netherlands Institute for
Sea Research, Texel, Netherlands
We studied the dissolved organic matter (DOM) assimilation by the common encrusting coral
reef sponge Halisarca caerulea. H. caerulea is found predominantly on the walls and ceilings
of coral cavities in the fore reef slope of the coral reefs of Curaçao (Netherlands Antilles) and
harbors sponge associated prokaryotes (2.1 *109 prokaryotes.cm-3 sponge). The assimilation
and respiration of 13C-enriched glucose and diatom derived dissolved organic matter was
followed in incubations. DOM was readily processed by the sponge with assimilation being the
major fate. The 13C- enrichments patterns in fatty acid biomarkers revealed that the dissolved
organic 13C assimilation by H. caerulea was both direct and mediated by sponge associated
prokaryotes. Tracer carbon was recovered both in bacteria-specific and non-bacteria specific
fatty acids. Phytanic acid was ascribed to the sponge. This is the first direct evidence of DOM
incorporation by sponge cells. The sponge-microbe consortium of H. caerulea processes bulk
dissolved organic matter, meeting up to 90% of their organic carbon demand. Because sponges
dominate live cover in cryptic habitats on coral reefs, DOM assimilation by cryptic reef sponges
represents an important, largely overlooked, ecological function of coral reefs.
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