Ocean Acidification, Temperature and Light Effects on Carbon-use Mechanisms, Calcification, and Growth of Tropical Macroalgae: Drivers of Winners and Losers

海洋酸化、温度和光对热带大型藻类碳利用机制、钙化和生长的影响：赢家和输家的驱动因素

• 批准号: 1416376
• 负责人: Marguerite Koch-Rose
• 金额: $ 42.28万
• 依托单位: Florida Atlantic University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2014
• 资助国家: 美国
• 起止时间: 2014-08-01 至 2019-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1416376&HistoricalAwards=false
• 关键词: Ocean; Acidification; Temperature; Light; Effects

Ocean sequestration of atmospheric CO2 enhances the availability of CO2 in seawater and lowers ocean pH, commonly referred to as 'ocean acidification'. Marine macroalgae are likely to respond to these two changes in ocean chemistry (elevated CO2 and acidification) in ways that have the potential to reduce the sustainability of coral reefs and other coastal ecosystems with potential economic consequences. There are two major forms of marine macroalgae on reefs: fleshy species that are characterized by a rapid growth potential which allows them to become 'nuisance species' and out-compete corals, and calcified species that are slower growing, but help cement the reef and promote coral larval settlement. Currently, there is very little information on fleshy macroalgal photosynthesis and growth responses to increased ocean CO2. Further, there is an inadequate understanding of ocean acidification effects on macroalgal calcification. The proposed research will examine the fundamental pathways of inorganic carbon uptake for photosynthesis across a range of pH and CO2 levels simulating ocean acidification into the future (2100). How photosynthesis, growth and calcification are modulated by light and temperature under ocean acidification will also be examined. These data will be used to identify ocean acidification effects on ecologically important macroalgae and consequential impacts to coral reef ecosystems. This research on marine macroalgae increases our understanding of ocean acidification effects on marine calcifiers, a research priority identified by the National Ocean Council. The research facility is sited at The Gumbo Limbo (GL) Nature Center that receives 100,000 visitors/yr and has educational programs supporting 15,000/yr K-12 students. This juxtaposition of research with an established outreach facility provides a unique opportunity to communicate OA science and its societal implications to a large public audience. Macroalgae responses to ocean acidification (OA) are likely to be distinctive compared to phytoplankton and microalgae due to their low surface area to volume ratios, high external boundary layer resistance to CO2 and higher irradiance requirements. Understanding specific mechanistic responses of tropical macroalgal photosynthesis and calcification to elevated pCO2, temperature and irradiance is critical to develop predictions of OA effects on macroalgal dominated communities of the tropics, including those that grow near their thermal limits. The research objectives are to (1) provide new insights into the biochemistry and physiology of photosynthesis and calcification that drive growth responses to OA and warming in ecologically important tropical macroalgal species, (2) elucidate photosynthetic C-use mechanisms in tropical species to understand OA influences on HCO3- use, (3) determine if photosynthesis-calcification processes become uncoupled by OA, (4) clarify the role of irradiance in photosynthetic and calcification responses to OA, and (5) examine the synergistic effects of OA, temperature and light on the thermal optima of photosynthesis and growth in species living close to their thermal limits. To meet these objectives, a series of short-term physiological experiments will be conducted to ascertain HCO3-use mechanisms, Ci uptake kinetics, potential to employ carbon concentrating mechanisms (CCMs), and species-specific linkages between photosynthetic C-use mechanisms and calcification in ten dominant fleshy and calcareous tropical macroalgae species. These biochemical and physiological data will subsequently be used to interpret longer-term (20 d) growth (organic and inorganic calcification and crystal formation) responses in aquaria studies conducted over three different seasons, and photosynthesis response surface experiments to gradients of pH, irradiance and temperature.

海洋封存大气中的CO2可以提高海水中CO2的可用性，降低海洋pH值，通常称为“海洋酸化”。 海洋大型藻类很可能对海洋化学的这两种变化（二氧化碳浓度升高和酸化）作出反应，其方式有可能降低珊瑚礁和其他沿海生态系统的可持续性，并产生潜在的经济后果。 珊瑚礁上有两种主要形式的海洋大型藻类：肉质物种，其特征是快速生长的潜力，使它们成为“滋扰物种”并与珊瑚竞争，钙化物种生长较慢，但有助于巩固珊瑚礁并促进珊瑚幼虫定居。 目前，关于肉质大型藻类光合作用和生长对海洋二氧化碳增加的反应的信息很少。 此外，人们对海洋酸化对大型藻类钙化的影响认识不足。 拟议的研究将研究在一系列pH值和CO2水平下光合作用无机碳吸收的基本途径，模拟未来的海洋酸化（2100年）。 还将研究光合作用、生长和钙化在海洋酸化下如何受到光和温度的调节。 这些数据将用于确定海洋酸化对具有生态重要性的大型藻类的影响以及对珊瑚礁生态系统的相应影响。 这项对海洋大型藻类的研究增加了我们对海洋酸化对海洋钙化物影响的理解，这是国家海洋理事会确定的研究重点。该研究设施位于Gumbo Limbo（GL）自然中心，每年接待100，000名游客，并拥有支持15，000名K-12学生的教育计划。这种研究与现有外展设施的并列提供了一个独特的机会，向广大公众传达OA科学及其社会影响。与浮游植物和微藻相比，大型藻类对海洋酸化的反应可能是独特的，因为它们的表面积与体积比低，对CO2的外部边界层阻力高，辐照度要求较高。 了解热带大型藻类光合作用和钙化的pCO 2升高，温度和辐照度的具体机制的反应是至关重要的发展预测OA对大型藻类占主导地位的社区的热带地区，包括那些生长在其热极限附近。 本研究的目的是：（1）为具有重要生态意义的热带大型藻类光合作用和钙化的生物化学和生理学提供新的见解，（2）阐明热带物种光合作用的C-使用机制，以了解OA对HCO 3-使用的影响，（3）确定光合作用-钙化过程是否因OA而解耦，（4）阐明光照在OA的光合作用和钙化反应中的作用;（5）研究OA、温度和光照对生活在其温度极限附近的物种光合作用和生长的最适温度的协同作用。 为了实现这些目标，将进行一系列短期的生理实验，以确定HCO 3的使用机制，Ci吸收动力学，潜在的采用碳浓缩机制（CCM），光合作用的C-使用机制和钙化之间的物种特异性联系在10个占主导地位的肉质和钙质热带大型藻类物种。 这些生化和生理数据将随后被用来解释长期（20天）的增长（有机和无机钙化和晶体形成）在水族馆的研究在三个不同的季节进行的反应，和光合作用响应面实验的pH值，光照度和温度梯度。