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| USGS Coral Microbial-Ecology Studies: |
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| Microbial Ecology of Deep-Sea Corals |
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Microbial Ecology of Deep-Sea Corals
[Christina Kellogg]
Most people are familiar with tropical coral reefs, located in warm, shallow waters. However, corals also exist hundreds and even thousands of meters below the ocean's surface where it is cold and completely dark. In the last few decades, scientists have discovered and photographed incredible gardens of deep-sea corals off the coasts of North America, Great Britain, Europe, Scandinavia, Australia, and New Zealand. These corals survive without algal symbionts (because there is no light for photosynthesis) and may take a long time to grow. Thus the potential role of coral-associated microbes is even more interesting. It is possible that the microbes are helping to feed these corals, similar to the chemosynthetic bacterial symbionts that feed hydrothermal-vent worms. The microbial communities of these coldadapted corals are also likely to contain novel organisms, which will not only increase our understanding of microbial diversity but could also be a source of new enzymes or pharmaceuticals.
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Left: The colorful landscape and incredible diversity of a deep-sea reef in the Aleutian Islands. Photo credit: Alberto Lindner, NOAA Fisheries. [larger version] |
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Above Left: Christina Kellogg collects samples of deep-sea corals for microbiological analysis as soon as they are brought to the surface. Photo credit: Anne Simpson, University of Maine. [larger version]
Above Right: Working in the high northern latitudes in the summer means it stays light all day and almost all night. This photo of the research ship Velero IV was taken at 10pm! Photo credit: Christina Kellogg, USGS. [larger version]
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Above Left: The volcano of Kanaga Island becomes visible through the fog as the Delta submersible prepares to dive for deep-sea corals. Photo credit: Christina Kellogg, USGS. [larger version]
Above Right: The Delta submersible was used to collect samples of deep-sea corals in the Aleutian Islands. [larger version]
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Above Left: Thouarella superba is one of the gorgonians (soft corals) that was sampled in the Aleutians for microbiological analyses. Photo credit: Robert Stone, NMFS/NOAA. [larger version]
Above Right: Paragorgea arborea, commonly known as bubblegum coral, was also collected for microbiological analyses. Photo credit: Robert Stone, NMFS/NOAA. [larger version]
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Study Site: Aleutian Islands
The Aleutian Islands are a string of volcanic islands stretching from Alaska toward Russia, dividing the North Pacific from the Bering Sea. Since 2002, National Oceanic and Atmospheric Administration (NOAA) fisheries scientists from the Auke Bay Laboratory have been documenting deep-water coral and sponge reefs in waters off these islands. The deep-sea corals that make up the Aleutian reefs are mainly gorgonians (soft corals). The diversity and abundance rival those seen in tropical coral reefs. During a 2004 cooperative research cruise, three types of gorgonians were collected with the Delta submersible for microbial analysis. Live bacteria and fungi have been cultured from these samples, and total microbial DNA was extracted so that molecular techniques could be employed to identify archaea and uncultured bacteria and fungi.
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Left: Bacteria, isolated from deep-sea corals, are grown on dishes of nutrient agar for identification and further study. Photo credit: Christina Kellogg, USGS. [larger version] |
Study Site: Gulf of Mexico
The deep-water coral Lophelia pertusa is globally distributed but is most common in the Atlantic Ocean. This hard branching coral forms bushes or thickets that provide extensive reef habitat for fishes and invertebrates. The USGS has partnered with the Minerals Management Service (MMS), NOAA, and the University of North Carolina to determine the biology and ecology of Lophelia reefs that have been discovered in the Gulf of Mexico. Using a submersible to collect samples and environmental data at depths to 800 meters, USGS scientists are determining the relationship between Lophelia and the reef's microbial flora; Lophelia's genetics, growth, metabolism, and reproduction; and food-web relationships of reef-associated organisms through the analysis of stable isotopes. Many of these Lophelia clumps are located near natural hydrocarbon seeps in the ocean floor, so it is of particular interest to determine if hydrocarbon-utilizing microorganisms are the link between the coral and the seeps. Samples of Lophelia were collected for microbial experiments in the summer of 2004, and additional samples will be collected in 2005.
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Above Left: Deep-sea coral samples were collected in the Gulf of Mexico using Harbor Branch Oceanographic Institute's Johnson-Sea-Link submersible. Photo credit: Cheryl Morrison, USGS. [larger version]
Above Right: Lophelia coral in the Gulf of Mexico provides a complex habitat for many organisms, including the rosefish, squat lobsters, and sea urchin seen here. Photo credit: Christina Kellogg, USGS. [larger version]
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Above Left: A small patch of Lophelia coral is surrounded by anemones. Photo credit: Christina Kellogg, USGS. [larger version]
Above Right: This close-up photo of a Lophelia branch shows the detail of a corallite-the small limestone cup the coral polyp secretes to protect itself. Photo credit: Cheryl Morrison, USGS. [larger version] |
Learn more about Lophelia at http://www.lophelia.org
This work continues as part of the DISCOVRE Project
continue to Microbial Wars: Mucus-Associated Bacteria Fend Off Coral Pathogens
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