Picture of Heidi Pearson

Heidi Pearson

Phone: 907-796-6271 (office)
Email: hcpearson@alaska.edu
Home: http://uashome.alaska.edu/~HCPEARSON
Office location: 205 C Anderson



"Blue carbon" is an emerging concept that describes how marine organisms can help to combat climate change by removing CO2 from the atmosphere. We are currently working on two projects to understand how the natural behaviors of marine mammals can aid in carbon sequestration. In particular, we are studying how the feeding behaviors of sea otters and humpback whales and can help to stimulate the growth of marine plants and contribute to the ocean’s ability to absorb carbon dioxide.

Sea otters help kelp forests to grow by feeding on organisms that graze on kelp, such as sea urchins. By keeping populations of kelp grazers low, sea otters allow kelp forests to flourish. In turn, kelp forests, like forests on land, absorb CO2 from the atmosphere. Thus, sea otters help in the formation of carbon sinks. We are measuring long-term changes in kelp forest canopy using NASA Landsat satellite imagery. For further information on how we can measure kelp from space, please read the Weblog from 3/11/2016. We are then correlating these changes in kelp forest canopy with changes in sea otter population during the same time period to identify the capacity for sea otters to promote kelp forest growth and in turn promote carbon sequestration. This work is part of our larger NSF-funded APECS project that is assessing the impact of sea otter recolonization on coastal sustainability in Southeast Alaska. For further information, go to the APECS page on the BREACH website and read this press release: https://www.nsf.gov/news/news_summ.jsp?cntn_id=189824&WT.mc_id=USNSF_8

In another Blue Carbon project, we are assessing how humpback whales can “fertilize” surface waters and stimulate the growth of phytoplankon. Humpback whales dive to depth to feed but then return to surface waters where they produce fecal plumes that are rich in limiting nutrients such as nitrogen and iron. These nutrients then stimulate the growth of phytoplankton, which stimulates the bottom of the food chain and absorbs CO2 from the atmosphere. We are comparing nitrogen concentration in humpback whale fecal plumes with control seawater samples to determine the extent to which humpback whales enrich Southeast Alaska waters.  

Taken together, these two projects will determine the positive effects these top predators can have on marine ecosystems. With the increasing populations of sea otters and humpback whales in Southeast Alaska, there is increasing potential for these marine mammals to help to reduce atmospheric CO2 levels. In climate action plans, it is thus important to consider these ecosystem services provided by marine mammals.