15 December 2000

American Geophysical Union Fall Meeting
Media Contact: Debbie Meyer, AGU press room, Dec. 15-19,
(415) 905-1007 or at MBARI (831) 775-1807, pressroom@mbari.org

SAN FRANCISCO, California—Scientists at the Monterey Bay Aquarium Research Institute (MBARI) have recently begun a series of novel experiments to address the potential biological impacts of deep-sea carbon dioxide sequestration. Initial results of these studies will be presented by MBARI scientist Mario Tamburri at the Fall 2000 meeting of the American Geophysical Union in San Francisco.

As international political interest increases for disposing of human-generated excess carbon dioxide in the ocean, scientists play a critical role for decision-makers in providing the necessary experimental data on its impacts. Previously, only theoretical models and shallow water studies have been available for estimating the possible effects of carbon dioxide storage on deep-sea biota. Tamburri and his colleagues have devised new field experiments, using MBARI's remotely operated vehicles, to make the first empirical observations.

The first field experiments were conducted in the summer of 1998 on the Monterey Canyon seafloor at a depth of 625 meters. MBARI's ROV Ventana was instrumented with a pH sensor and a special odor/carbon dioxide release rig that were used to test the responses of mobile animals to dissolving carbon dioxide hydrates—an ice-like form of the gas that occurs naturally at low temperatures and high pressures. The researchers created these hydrates by injecting liquid CO2 into a beaker. The ROV released an odor solution to attract mobile deep-sea animals to the beaker and its dissolving hydrates. The interactions of animals—sablefish, hagfish, dover sole, urchin, and snail—were recorded on video and analyzed in the laboratory. The tests revealed some surprises.

"Previous work assumed that animals encountering the carbon dioxide-rich waters would avoid the solution due to the correspondingly low pH of the water," said Tamburri. "Instead, the animals continued to be attracted by the odor solution."

Testing another possible carbon dioxide disposal scenario, the scientists repeated similar experiments at a depth of 250 meters using a carbon dioxide-saturated solution. An instrument on Ventana released a fish odor solution into the water to attract fish. In this study, the animals would come in brief contact with the CO2-saturated odor solution, back away, then return.

To address questions about the effects of carbon dioxide disposal on deep-sea benthic communities, MBARI scientists began new experiments last spring using ROV Tiburon at a depth of 2,995 meters. Their preliminary tests have helped them develop the tools that will be used for follow-on studies next year.

While many of the initial results in these experiments were unexpected, the biological impacts of carbon dioxide disposal on the deep sea may be relatively benign, according to Tamburri, particularly when compared to other human impacts on the ocean. But clearly there is much more work to be done.

"Our initial work has established the methodologies needed to examine questions about the ecological effects of deep sea carbon dioxide disposal options. We've gained important new insight into the factors that must be considered before the feasibility of ocean CO2 disposal can be evaluated completely," said Tamburri.

Related sessions at AGU 2000 Fall Meeting
B11D-07, Monday 10:20, MC 103
Brewer, et al. Progress in direct experiments on the ocean disposal of fossil fuel CO_2.

B22C-08, Tuesday 15:45, MC 103
Tamburri, et al. Determining the effects of carbon dioxide ocean disposal on deep-sea organisms.

Related publications
Tamburri, et al. A field study of the effects of CO₂ ocean disposal on mobile deep-sea animals. Marine Chemistry 72 (2000) 95-101.

Brewer, et al. Direct Experiments on the Ocean Disposal of Fossil Fuel CO₂. Science, 7 May 1999, 284: 943-945.

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