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Scientist Spotlight: Brendan Roark

November 15, 2010

Dr. Brendan Roark

Dr. Brendan Roark

Brendan Roark is a biogeochemist with Texas A & M University. He completed his undergraduate degree in environmental conservation at the University of Colorado Boulder, and his Ph. D. in geography at the University of California at Berkley.

Brendan is participating in the Deep Corals Expedition because he hopes to obtain samples of black, gold, pink, red, and bamboo corals. He studies these corals because samples of these species have been collected from the Pacific and Gulf of Mexico, the black and gold coral species are amongst the longest-lived deep sea corals, and they are the best suited for paleo-oceanographic reconstruction, which is modeling past ocean environmental conditions.

Brendan scrapes a black coral for tissue samples for age determination

Brendan scrapes a black coral for tissue samples: Photo by R. Peyton Hale

During this mission some tissue samples will be collected, but the bottom-most portion of the coral, where it attaches to the ocean floor, is of primary interest because this is the part of the coral that can be used to determine how old the coral is and how fast it grows. A variety of instruments are used to take sub-samples. He works from the outside to the center of the coral. Once the samples are taken, an accelerator mass spectrometer (AMS) is used to measure the amount of radiocarbon present in each coral sample, which allows researcher to determine the age of the coral specimens. This radiocarbon dating technique is also used by geologists and paleontologists to determine the age of rock layers and fossils. All living things contain carbon and constantly exchange carbon with the atmosphere or ocean. When an organism dies, it no longer exchanges carbon, and the carbon begins decaying. Radiocarbon dating is used for specimens up to 50,000 years old.

Knowing the age and growth rates of deep sea corals is important for the management and conservation of these organisms and their habitats. Deep sea coral age and growth rate data can also help scientists track changes in climate over time. Ocean sediment cores help reconstruct climate change over hundreds of thousands of years. Tropical corals can be used for short-term (a few hundred years) climate changes in surface conditions at tropical latitudes. The oldest black coral life span scientists have dated was 4200 years. Bamboo and pink corals sampled so far indicate a much shorter life span of a few hundred years. Using deep sea coral to reconstruct past climate changes fills in the gap between the long time frames of ocean sediment cores, and short time span of tropical corals. This helps to build a better picture of how climate has changed throughout earth’s history.

Brendan enjoys his field research in the ocean — collecting samples via submersibles and remotely operated vehicles (ROVs). He also enjoys using the scientific instruments utilized for analytical research, and the time spent collaborating with colleagues.

Interview with Brendan Roark (mp3)

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