Ocean Acidifcation, Climate's Step Sister
Dr. J. Timothy Wootton, a professor in the Department of Ecology & Evolution at The University of Chicago began studying the ecological impacts of ocean acidification using data collected at Tatoosh Island, a group of small islands off the coast of Washington’s Olympic Peninsula over eight years ago. He and his colleagues collected data on pH, salinity, and temperature. Their results were disturbing.
“pH declines were occurring at a much faster rate than we expected,” said Dr. Wootton. The rate of decline of pH was more than an order of magnitude higher than the simulation models for the area had predicted – that is, the ocean around Tatoosh Island was become acidic ten times faster than hypothesized.
But the effects of pH decline are more subtle than the astronomical rate of change might suggest.
In a research paper published in 2008 by the National Academy of Sciences (NAS), Dr. Wootton noted that there is a “web of species interactions” that makes the ecological response to increased acidity far more complex than summary observation describes. His data showed a decrease in populations of two species of mussel, as well as in the abundance of a barnacle species. In contrast, the population of a second barnacle species, the acorn barnacle, and fleshy algae increased. In the Tatoosh Island ecosystem, Dr. Wootton and his and his colleagues observed that the pattern of species replacement changed in response to decreasing pH. Algae actually benefited. And algae remove CO2 from the atmosphere through photosynthesis.
“The emphasis has been on species with calciferous skeletons, exoskeletons,” said Dr. Wootton. “In truth, ecosystem response to changing pH is neither a simple function of having a certain kind of shell, or of decline in organism performance.”
We’d like solutions to complex problems to be simple. Often they aren’t. The overall effect on marine life of changing pH will have far-reaching consequences for the ocean ecosystem.