The cold dark expanses of the ocean floor may provide clues to the extent and effect of climate change on undersea ecosystems, said Ron Kaufmann, associate professor of marine science and environmental studies at the University of San Diego.
Kaufmann was one of the authors of a paper published this fall, in the Proceedings of the National Academy of Sciences (PNAS). The paper was based on analyzing data from nearly 20 years of research on the composition and functions of deep-sea communities in two widely separated locations, one in the northeast Pacific and one in the northeast Atlantic. The findings show how animal communities on the abyssal seafloor are affected by climate change.
These types of changes are expected to be part of the global discussion at the United Nations Climate Change Conference in Copenhagen, which opens Dec. 7.
Historically, marine scientists have considered abyssal plains, more than 2,000 meters below the sea surface, to be relatively isolated and stable ecosystems. But the study, led by the Monterey Bay Aquarium Research Institute, found that changes in the earth’s climate can cause unexpectedly large changes in deep-sea ecosytems. The PNAS paper covers two time-series studies, one at “Station M” about 220 kilometers off the central California coast, and another on the Porcupine Abyssal Plain, several hundred kilometers southwest of Ireland.
In these cold, dark environments, very little food is available. What food there is takes the form of bits of organic debris drifting down from the sunlit surface waters.
“The climate in the north Atlantic and north Pacific has been linked to the amount of and quality of food reaching the deep-sea floor in the form of sinking organic material that has its origins in the surface waters of the ocean,” Kaufmann explained. “Climate change could lead to a reduction in the food supply to deep-sea communities, as well as a decline in food quality. Changes in food supply could lead to shifts in the species that make up deep-sea communities. Larger organisms that require more food to sustain life could be replaced by small organisms that can survive on less.”
The authors of the PNAS paper conclude that long-term climate change is likely to influence deep-sea communities. Kaufmann said more work is needed to study ocean ecosystems. “If we hope to understand how the world’s largest ecosystem functions on long-time scales and in more than a few widely spaced locations, we need to establish programs to study the deep sea over long periods of time at a number of places. New technology in the form of ocean observatories could contribute greatly to this goal.”
The research at Station M was sponsored by grants from the National Science Foundation and the David and Lucille Packard Foundation. Research at the Porcupine Abyssal Plain Sustained Observatory site was supported by the European Union and the Natural Environment Research Council of the United Kingdom.
— Liz Harman
Image credit: © 2007 MBARI
A small grenadier fish swims over the seafloor at Station M. Between 1989 and 2004, the number of grenadier at Station M doubled. This photograph (above) was taken using an underwater camera whose time-lapse photographs show changes in the number and types of animals on the deep seafloor.