Harley, Christopher - University of British Columbia

个人简介

I study climate change impacts on rocky coasts. I’m interested in how climatic factors, such as temperature, CO2, and pH, and biological relationships, such as predation and facilitation, interact to create ecological patterns in time and space. Sarah Nienhuis (MSc student) Sarah is using her background in chemistry to explore the effects of carbon dioxide enrichment / acidification on marine trophic pairs. She is conducting laboratory studies on the feeding and assimilation rates of sea urchins, and will soon begin working on potential changes in algal palatability in the lab and community level change in the field. Penny White (MSc student) Penny is interested in the ecology and cultural value of Porphyra abbotti, a seaweed that is harvested by First Nation communities in British Columbia. Her thesis combines genetics, sociology, and ecology to understand recent changes in the species’ distribution, and how local harvesters are responding. Penny is co-supervised with Sandra Lindstrom in UBC’s Botany Department.

研究领域

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Temperature, carbon dioxide, and interspecific interactions As I see it, there are two major challenges in figuring out how marine ecosystems will be affected by climate change. First, although most scientists study one variable at a time, temperature and carbon dioxide concentrations (and thus the pH of seawater) are changing simultaneously. For physiological reasons, it is likely that changes in both temperature and pH together will be worse than predicted from change in either factor along. Second, although a great deal of research has shown how climate variables affect individuals, much less is known about how climate change will impact communities. Thus, research on interactions among species is badly needed. I have recently received funding for a system of mesocosms (fancy fish tanks) in which temperature, carbon dioxide, and species interactions can be simultaneously manipulated. I hope to use this system to see how climate change may impact organisms directly, by changing growth and mortality rates, and indirectly, by changing the effectiveness of predators or the palatability and accessibility of prey. The thermal ecology of a marine symbiosis One of my ongoing projects involves the relationship between the mussel Mytilus californianus and a cyanobacterial parasite that bores into its shell. The parasite is bad news, because it causes the shell to become weak and brittle. Eventually, the shell may break, which leads to the death of the mussel. Death is bad for mussels. But the news isn’t all bad. As the shell erodes, the black periostracum (the outer layer of the shell) sloughs away, and the resulting shell color is light gray. Light gray shells absorb less solar energy than black ones, and therefore stay cooler. This is interesting because the relationship between the mussel and the “parasite” changes from parasitic to mutualistic depending on the thermal environment. For example, the mussels that survived a major heat wave tended to be more parasitized (i.e. had less black surface area on their shells) than mussels that died. Intriguingly, this relationship and its obvious implications for global warming may also depend on CO2. Increasing CO2 concentrations reduce the pH of seawater, which in turn makes it more difficult for mussels to repair their shells. I plan to further investigate the role of temperature and CO2 in determining the ecological consequences of this important symbiosis. Simulating global warming on rocky shores Comparative studies of increasing temperature across spatial gradients are great, and at large scales, they are the only option short of waiting for climate change to occur. However, I am also beginning to directly manipulate temperature in marine systems. Sarah Nienhuis and are planning on manipulating temperature in experimental tidepools to address the influence of temperature on community structure. Darwin’s barnacle and the invasion of Argentina I have a long history of research projects on the barnacle Balanus glandula, a species first described by Charles Darwin. Balanus is an important ecosystem engineer, because it creates habitat (nooks and crannies between barnacles) for many other species. Balanus has recently invaded Argentina, and has spread over ~20 degrees of latitude in under 40 years. I am working with Evangelina Schwindt at the Patagonian National Center to determine the rate of spread, to compare population dynamics between hemispheres, and to determine the community level impacts of Balanus in its recently invaded range. Other projects In addition to the research described above, I am actively collaborating on heat budget modeling and other biophysical approaches (with Mark Denny at Stanford), on regional-scale patterns of thermal stress in mussel beds (with Brian Helmuth at the University of South Carolina), on the mechanisms underlying the color polymorphism in Pisaster (with Mirjam Held, an undergraduate student at UBC), and on long-term biological change on rocky shores (with Bob Paine at the University of Washington). Information for prospective students In general, I hope to accept one or possibly two graduate students every fall. If you are interested in working in my lab, here are a few useful pieces of information. First, UBC is great, Vancouver is great, and marine ecology in British Columbia is especially great. Next, I am still relatively new here, and my level of funding is still relatively low. Thus, at this stage, it will be very difficult for me to accept students who do not have their own funding (NSERC fellowships for Canadians, NSF fellowships for Americans, or similar support). To discuss the possibilities of joining my lab, please send me an email. Emails that contain research interests, a CV, and unofficial transcripts are particularly helpful.