Collaborative Research: Ocean Acidification-Category 1: Effects of pCO2 and pH on Photosynthesis, Respiration and Growth in Marine Phytoplankton

大约三分之一的二氧化碳排放溶解在海洋的表层水中，增加了海洋的酸度（海洋酸化现象）。海水酸化的生物效应之一是浮游植物生长的变化，而浮游植物是海洋食物网的基础。然而，已经报道了二氧化碳浓度增加对浮游植物生长的不同影响，包括增加、不影响或减少。该项目的目的是了解海洋浮游植物对二氧化碳浓度和酸度增加的生理反应。这些知识将使评估并最终预测浮游植物生态和海洋生产力的未来变化成为可能。要验证的假设是，二氧化碳的增加和酸度的增加（pH值的降低）都会影响海洋浮游植物的生长。假设1)二氧化碳浓度的升高会导致光合效率的提高，2)海水pH的降低会减少浮游植物维持其正常内部pH所需的能量。浮游植物的光合和呼吸生理差异是否会导致浮游植物对二氧化碳浓度和海洋酸度的不同反应，我们将进行实验研究。这些假设将在实验室实验和补充的实地研究中进行测试，使用质谱技术和分子标记分析来追踪碳和氧代谢。天然浮游植物的实地实验将在新泽西沿海水域、百慕大和加州铁限制水域进行。更广泛的影响该项目解决了一个社会关注的重大问题，将为本科生提供研究经验，为研究生和博士后提供培训。来自当地大专院校的暑期实习生将参与该项目。将针对初高中学生和教师开发以问题为基础的气候变化和海洋酸化学习包。主要研究人员将与气候中心（Climate Central）合作。气候中心是一家非营利组织，负责为网络、电视台和其他向公众提供信息的渠道准备媒体内容。

Approximately one third of carbon dioxide emissions dissolve in the surface waters of the ocean and increase its acidity (the phenomenon of ocean acidification). Amongst the biological effects of seawater acidification are changes in the growth of phytoplankton, organisms that are the basis for marine food-webs. However, variable effects on phytoplankton growth of increasing carbon dioxide concentration have been reported, including an increase, no effect or a decrease. The objective of this project is to understand the physiological response of marine phytoplankton to increasing concentrations of carbon dioxide and acidity. This knowledge will make it possible to assess, and eventually predict, future changes in phytoplankton ecology and ocean productivity. The hypothesis to be tested is that the increase in carbon dioxide and the increase in acidity (a decrease in pH) both influence the growth of marine phytoplankton. It is postulated 1) that elevated carbon dioxide levels will lead to a higher photosynthetic efficiency, and 2) that a lower pH of seawater will decrease the energy that phytoplankton must spend to maintain their normal internal pH. Experiments will be carried out to test if differences in photosynthetic and respiratory physiology between phytoplankton species will result in different responses to carbon dioxide concentration and ocean acidity. These hypotheses will be tested in laboratory experiments and complementary field studies, using mass spectrometric techniques and the analysis of molecular markers to trace carbon and oxygen metabolism. Field experiments with natural phytoplankton will be carried out in New Jersey coastal waters, Bermuda, and iron-limited waters off California.Broader ImpactsThis project, which addresses an issue of significant concern to society, will provide research experiences for undergraduates and training for graduate students and a postdoctoral fellow. Summer interns from local junior colleges will participate in the project. A problem-based learning package on climate change and ocean acidification targeting middle and high school students and teachers will be developed. The principal investigators will work with Climate Central, a nonprofit organization that prepares media content for the web, television stations and other outlets that provide information to the public.