Christopher Wilmers, UC Santa Cruz
We combine data collected over the last 40 years to estimate the indirect effects of sea otters on ecosystem carbon production and storage across their North American range from Vancouver Island to the western edge of the Aleutian Islands. We find that sea otters, by suppressing sea urchins, substantially increase kelp ecosystem productivity and have a strong influence on kelp carbon flux and storage. Over an ecosystem area of approximately 5.1 x 1010 meters, the effect of sea otter predation on living kelp biomass alone is approximate to 5.6-11% of the carbon contained in the volume of atmosphere above the North American sea otter range; 21-42% of the increase in atmospheric carbon since pre-industrial times in that same volume of atmosphere; or the carbon emissions from 5 million cars in an average year. This stored carbon would be valued at $304-603 million on the European Carbon Exchange. Results support evidence that predator-driven ecosystem changes influence the rates of carbon flux and storage in many other species and ecosystems.
Journal article in Frontiers in Ecology and the Environment: Christopher C Wilmers, James A Estes, Matthew Edwards, Kristin L Laidre, and Brenda Konar. 2012. Do trophic cascades affect the storage and flux of atmospheric carbon? An analysis of sea otters and kelp forests. Frontiers in Ecology and the Environment 10: 409–415. http://dx.doi.org/10.1890/110176