Award: OCE-1316040

Ocean acidification (OA) is a change in water chemistry that occurs as anthropogenic carbon dioxide (CO2) equilibrates from the air into seawater. In temperate areas, water chemistry, including acidity, can show a strong seasonal cycle, due to changes in sunlight (used for photosynthesis, which absorbs CO2) and temperature. OA can have serious impacts on marine animals, especially those that form shells or skeletons from calcium carbonate, such as corals, oysters and clams. In this project we studied the effects of ocean acidification on a shell-forming planktonic pteropod (a group of marine snails) called Limacina retroversa. We were particularly interested in whether the biology of the animal changes over the course of the year in relation to seasonal changes in water chemistry. We sampled pteropods from the Gulf of Maine during all four seasons and studied their shell condition, locomotion, respiration rate, reproduction and gene expression patterns. We found that these pteropods can reproduce throughout the year but appear to have a predominantly seasonal cycle. They showed natural seasonal variability in both shell condition and gene expression. Shells condition was worst in January, when water is naturally most acidic. We conducted experiments throughout the year exposing pteropods to different CO2 levels for up to two weeks. Importantly, we found evidence that animals varied in their sensitivity to CO2 across the year, which indicates a response (acclimatization) to the seasonal environmental conditions. For example, respiration rates were most sensitive to CO2 exposure in the lab in April, when environmental CO2 is naturally lowest. Gene expression varied more across seasons within the natural population than in response to either captivity or experimental CO2 exposure. These seasonal differences appear to be related to lipid metabolism and biomineralization that may be linked with developmental progression and overwintering strategies. In the lab, as the duration and severity of CO2 exposure increased, we observed consistent gene expression changes related to biomineralization, acid-base regulation, metabolism and neural signaling transcripts. Several of these genes can serve as biomarkers of acidification stress responses. Six scientific papers have been published describing these results, and a seventh is currently in review. Multiple presentations have been given at domestic and international meetings describing these results for scientific audiences, and three students have completed Ph.D. dissertations related to this project. All of the molecular and environmental data are publicly available. Broader impacts of the work included training of three Ph.D. students and one postdoctoral investigator. The postdoctoral investigator assumed substantial leadership responsibilities and has since accepted a faculty position and established her own lab. Multiple photos from the research cruises and experiments, with associated informative captions, have been featured as the "Image of the Day" on WHOI?s main website and in the WHOI Oceanus Magazine. These venues are the main portals by which WHOI interacts with the public. Additional outreach included public talks at the Bermuda Institute of Ocean Sciences (Plankton, and Ocean Acidification), inclusion of the material in popular science TV episodes (the Water Brothers and NOVA) and as educational content in the 2014 National Ocean Science Bowl and a PBS Learning Media video. Working with sculptor Cornelia Kavanagh and Smithsonian personnel, the Lawson Lab developed an exhibit that was displayed in the Sant Ocean Hall of the National Museum of Natural History entitled "Fragile Beauty: The Art and Science of Sea Butterflies." Lawson worked with personnel in the Ocean Hall's education group to develop a variety of educational materials and an associated script used on an interactive cart tended by docents. A related version of this exhibit was developed for the Peabody Essex Museum in Salem, MA as part of a 1-year exhibit entitled "Sizing it Up: Scale in Nature and Art." Data and meta-data generated by this project are available at the NSF Biological and Chemical Oceanography Data Management Office (BCO-DMO): http://www.bco-dmo.org/project/2263. Last Modified: 09/11/2017 Submitted by: Gareth L Lawson