Award: OPP-1246293

Climate change projections for this century suggest that the Southern Ocean will be the first region to be affected by seawater chemistry changes associated with enhanced atmospheric carbon dioxide (CO2) that is absorbed by the ocean, a process termed ocean acidification. Elevated CO2 can impact the metabolism, growth, and reproduction of marine organisms. Concurrently with ocean acidification, rapid warming in the Western Antarctic Peninsula (WAP) region is occurring and is associated with an overall decline in primary, secondary, and higher trophic levels, including Antarctic krill (Euphausia superba), a key species in Antarctic food webs. Ocean acidification and warming may act together to impair animal performance, which could eventually negatively impact a krill population that has declined two-fold since the mid-1970s. However, no prior studies measured Antarctic krill metabolism, growth, or reproduction in the context of ocean acidification or synergistic "greenhouse" conditions of elevated CO2 and temperature. Intellectual Merit: Our study examined feeding, growth, and metabolic responses of Antarctic krill exposed to elevated CO2 and temperature. By conducting multiple laboratory experiments during two field seasons at Palmer Station, Antarctic, we illustrated high variability in responses of Antarctic krill to acidification. A comparison of krill exposed to elevated CO2 and elevated CO2/temperature for short (48 hours) or extended (3 weeks) time periods prior to feeding experiments demonstrated that krill may have the ability to acclimate to elevated CO2, but remained sensitive to elevated temperature or the interaction between elevated CO2 and temperature. Additionally, krill growth and metabolic rates were primarily impacted by elevated temperature, and elevated CO2 had a minimal impact. Results from this project suggest that juvenile and adult krill are relatively tolerant of high CO2. Instead, physiological impacts from warming temperatures were more pronounced and thus will likely outweigh any negative effects on krill physiology from future acidification in regions of Antarctic with rapid rates of warming. However, warming temperature had a more pronounced impact on krill physiology compared to acidification, suggesting continued warming in the WAP region, and potentially other Antarctic regions, will drive Antarctic krill response. Additionally, food supply likely plays a large role on how krill respond to environmental stressors. Low food concentration is an added stressor, while high food availability may aid Antarctic krill in successful acclimation to increases in temperature and CO2. Results from this project, combined with previous studies conducted by other research groups focused on ocean acidification impacts on Antarctic krill egg hatching success and larval development, provide a more complete picture of krill response during their multi-stage life cycle and as such contribute to greater understanding of potential trajectories of Antarctic krill health and abundance and potential associated feedbacks on the ecosystem and biogeochemical cycles. Broader Impacts: Our project included a strong broader impacts component that reached a wide audience in land-locked Kansas through a year-long initiative called Project PARKA (Planting AntaRctica in KAnsas; http://coseenow.net/project-parka/). We worked with 22 educators and their students from high schools throughout Kansas. The core educational objectives of this proposal were to 1) instruct students about potential careers in marine science, 2) engage students and promote their interest in the scientific process, critical thinking, and applications of science, mathematics, and technology, and 3) and increase students? and teachers? awareness and understanding of the oceans and global climate change, with special focus on the Western Antarctic Peninsula region. An additional goal was for students to conduct their own, similar research concurrently to our field season. We held a 2-day educator workshop July16-17, 2013, introducing our study to the educators who then taught the material in their classrooms the following school year. The students followed our first field season (2013-2014) online, reading and commenting on our Scientist Blog. In January 2014, the teachers and students joined the Palmer Station field team remotely for a series of video teleconferences. On April 15, 2014, we hosted a one-day science symposium in which the students presented the results of their independent research to some of our research team, heard career perspectives from a wide range of scientists, and participated in a Q&A panel session with the scientists. The close interactions between scientists, educators, and students throughout the research mission and the inclusion of independent student research increased educator and student understanding of the scientific process. Additionally, PARKA education and outreach efforts assisted in the development of NSF funded Polar Interdisciplinary Coordinated Education (ICE) (grant #OPP-1525635), serving 48 educators and more than 3,000 students in inquiry-based learning. Last Modified: 08/10/2018 Submitted by: Grace K Saba