Ocean acidification

The Environmental Data from Tatoosh Island

As carbon dioxide concentrations in the atmosphere increase, the pH of ocean water is expected to decrease. Our long-term research on Tatoosh Island supports a scenario of decreasing pH through time, and the declines we have measured are greater than those predicted by models (Wootton, Pfister & Forester 2008, Wootton & Pfister 2012).  Ongoing work is continuing to quantify this pattern as well as understand the implications for calcium-bearing organisms and their role in the nearshore community.

nat geo Dec2016
From National Geographic Magazine, December 2016


California Mussels Provide an Archive for Change

With funding from the SeaDoc Society, we used the shells of California mussels, both ancient and modern, to document rapid changes over the past decade in the stable carbon isotopes of shell material (Pfister et al. 2011). In collaboration with a number of colleagues, we also show that mussel shells are thinner today than they were in the past (Pfister et al. 2016, Proceedings Royal Society B).

Coralline Algae Reveal a Changing Environment

Sophie McCoy, a graduate of the lab and now faculty at Florida State University, has been studying the effects of ocean pH changes on crustose coralline algae. She finds crust thinning in the previous dominant competitor (McCoy 2013), as well as a reversal of fortune for the top competitor. Compared with Bob Paine’s experimental investigations of coralline overgrowth in the 1980s, Sophie has documented increased losses by the top competitor and a quantitatively changed interaction network in nature (McCoy & Pfister 2014, Ecology Letters) and in silico (McCoy et al. 2016, Proceedings of the Royal Society B).


Seaweeds Interact with Seawater Chemistry

The vast kelp forests, dense macrophytes and calcifying animals and plants likely have important feedbacks with seawater.

koitlahjul2016With funding from the NOAA Climate Change Program, I am investigating how kelp beds in Washington state interact with carbon and nitrogen cycling. Vast kelp forests of Nereocystis and Macrocystis occur on the shores of Washington state. We are asking when these kelp act as carbons sinks or sources, what their role is  for nitrogen cycling, and about the nature of their interaction with phytoplankton and microbes.

Courtney Stepien, former PhD student in the lab,  documented the range of carbon use patterns in seaweeds (2015, Journal of Ecology) and the strong effects that seaweeds can exert on the pH and buffering capacity of seawater around them (Stepien, Pfister, Wootton 2016, PloSONE).


Will species adapt to changing ocean pH?

Graduate student Mark Bitter is investigating the capacity for mussels to deal with decreasing pH. By contrasting areas with variable versus constant pH, both in the field and in controlled mesocosms, Mark is asking whether species from variable environments will be at an advantage in a changing ocean. Some of Mark’s research is hosted by Drs. Jean-Pierre Gattuso and Lydia Kapsenberg at the Laboratoire d’Océanographie de Villefranche-sur-Mer in France. We thank the France and Chicago Collaborating in the Sciences (FACCTS) program for support.


See The New York Times article about our work related to climate change

See a video about our research about ocean acidification made by Oregon Public Broadcasting

Link to a University of Chicago blog about our work demonstrating rapid decline in the stable carbon isotope value of mussels shells on Tatoosh Island

For more about this important topic, see the Ocean Carbon and Biogeochemistry site for the Ocean Acidification subcommittee.

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