Ocean acidification is one of the most pressing marine science issues of our time, with potential biological impacts spanning all marine phyla and potential societal impacts affecting man's relationship to the sea. Rising levels of atmospheric pCO2 are increasing the acidity of the world oceans. It is generally held that average surface ocean pH has already declined by 0.1 pH units relative to the pre-industrial level (Orr et al., 2005), and is projected to decrease 0.3 to 0.46 units by the end of this century, depending on CO2 emission scenarios (Caldeira and Wickett, 2005). The overall goal of this research is to parameterize how changes in pCO2 levels could alter the biological and alkalinity pumps of the world ocean. Specifically, the direct and indirect effects of ocean acidification will be examined within a simple, controlled predator/prey system containing a single prey phytoplankton species (the coccolithophore, Emiliania huxleyi) and a single predator (the oceanic metazoan grazer, Calanus finmarchicus). The experiments are designed to elucidate both direct effects (i.e. effects of ocean acidification on the individual organisms only) and interactive effects (i.e. effects on the combined predator/prey system). Interactive experiments with phytoplankton prey and zooplankton predator are a critical starting point for predicting the overall impact of ocean acidification in marine ecosystems. To meet these goals, a state-of-the-art facility will be constructed with growth chambers that are calibrated and have highly-controlled pH and alkalinity levels. The strength of this approach lies in meticulous calibration and redundant measurements that will be made to ensure that conditions within the chambers are well described and tightly monitored for DIC levels. Growth and calcification rates in coccolithophores and the developmental rates, morphological and behavioral effects on copepods will be measured. The PIC and POC in the algae and the excreted fecal pellets will be monitored for changes in the PIC/POC ratio, a key parameter for modeling feedback mechanisms for rising pCO2 levels. In addition, 14C experiments are planned to measure calcification rates in coccolithophores and dissolution rates as a result of grazing. These key experiments will verify closure in the mass balance of PIC, allowing the determination of actual dissolution rates of PIC within the guts of copepod grazers.
The team of scientists in this work contributes expertise in coccolithophore ecology, biogeography and physiology (Balch) and copepod ecology and physiology (Fields). They will be joined by a post-doctoral fellow and a highly capable technical staff to provide the necessary support to cultivate and monitor cultures during experiments. Six supervised undergraduate students will have projects associated with this work. Expertise in carbonate chemistry will be provided by Dr. N. Bates (consultant, see letter of support).
Broader Impact. Along with the numerous scientific and societal broader impacts of ocean acidification, there are also significant educational impacts associated with this work. This project has numerous self-contained sub-projects that will provide exceptional opportunities for motivated undergraduate students to receive hands-on research experience, learning sophisticated culturing techniques, the fundamentals of optics and micro-videography. Six supervised undergraduate students will have projects associated with this work. Students will be required to meet weekly and to give a Bigelow seminar on their respective projects. Participation at national meetings will be encouraged and supported. Balch and Fields have had great success with undergraduate students in the past with several receiving authorship on publications that incorporated their work. They will also invite several high school students into the lab to assist with basic aspects of the project. Fields is involved in the COSEE program (designed to bring ocean science to rural areas) and the "Keller Bloom" project, which provides a week-long science immersion course to gifted high school students from rural Maine. Results of the project will also contribute to the development of other BLOS educational and outreach programs, most notably weekly summer seminar series open to the public, the summer REU program and a new Colby College semester program at Bigelow Laboratory. Funds from this proposal will be used to build a state-of- the-art facility for creating, maintaining and monitoring pCO2 concentrations.
