Climate change and the costs of survival in two species of marine crabs with contrasting abilities to compensate for environmental change

过去250年来人类活动造成的二氧化碳在大气中的积累，正在使世界海洋发生数百万年来从未见过的迅速变化。大气中二氧化碳的增加导致海洋表面温度上升（过去100年为0.6摄氏度），并由于降雨量增加和陆地冰川和冰盖融水的输入而导致海洋的扩张和稀释。此外，海洋吸收了自前工业时代以来人类产生的约三分之一的二氧化碳。由此导致的海洋pH值降低，也称为海洋酸化（OA）和碳酸盐浓度正在引起一些警报，因为许多海洋无脊椎动物，如珊瑚，棘皮动物和软体动物依赖海水碳酸盐来源来钙化它们的外壳和骨骼。此外，这些群体在很大程度上不能忍受环境压力，适应变化的能力有限。因此，它们被认为是对海洋中预计发生的与气候有关的变化最敏感的。目前有一个真实的担忧，许多这些物种将经历人口下降，甚至可能灭绝。这将通过影响群落互动和群落结构，导致海洋生态系统生态发生不可逆转的变化。然而，最近已经变得明显的是，通常被认为对预测的变化更有容忍力的分类群和物种也可能受到威胁。这种认识是因为最近对OA的长期反应（数周至数月）进行了检查，以响应多个变量，即通常是OA加上温度。现在看来，能够在生理上补偿和缓冲环境破坏引起的变化的生物体可能会受到这些环境变化的间接影响，因为这种调整最终是能量昂贵的。目前，还不知道随着时间的推移，这些生物体会发生什么，因为补偿所需的能量可能会从其他重要过程（如免疫功能和生长）中转移，导致对疾病的易感性增加和生长速度降低。本项目的目的是建立补偿能力之间的联系，能源的使用和性能在2种brachyuran螃蟹不同的能力，以补偿变化。来自欧洲以外具有生态重要性和高度入侵性的物种Carcinus maenas和具有商业重要性的物种Cancer pagurus的第一年幼蟹将暴露于升高的pCO2（0.08 kPa-到2100年预测的水平）和降低的盐度（~80%）长达18个月。关键的生理问题是这两个物种是否能够调整它们的生理机能以继续发挥最佳功能，以及这些调整是否在代谢上代价高昂，并且可以随着时间的推移而维持。关键的生态问题将是这些代价高昂的变化是否会损害个体的适应性和表现，并有可能损害种群规模。一个项目奖学金将与主要项目平行进行，使我们能够调查高pCO2和低盐度对三种短尾蟹，C。maenas角pagurus和Necora puber。该奖学金将调查幼虫发育和性能的变化，这可能会影响幼虫的招聘，因此将确定潜在的人口瓶颈。这项提议是班戈尔和南安普顿研究人员正在进行的合作的结果。这些研究小组参与了一些国家和国际OA研究项目，但已经确定，我们有限的理解pCO2和盐度的相互作用，加上缺乏信息的海洋甲壳类动物的OA的反应，是现有的研究工作的弱点。

The accumulation of CO2 in the atmosphere as a result of human activities over the past 250 years is causing rapid changes in the World's oceans towards conditions not seen for millions of years. Increased atmospheric CO2 is leading to an increase in sea surface temperature (0.6C in the past 100 years) and is causing an expansion and dilution of the oceans due to increased rainfall and input of melt water from terrestrial glaciers and ice sheets. In addition, the ocean has absorbed about one third of the CO2 produced by humans since pre-industrial times. The resulting reductions in ocean pH, otherwise known as Ocean Acidification (OA) and carbonate concentrations are causing some alarm, as many marine invertebrates such as corals, echinoderms and molluscs depend on seawater carbonate sources to calcify their external shells and skeletons. Moreover, these groups are largely intolerant of environmental stress and are limited in their abilities to adjust to change. As a result they are considered to be the most sensitive to the climate-related changes expected in the oceans. Currently there is a real concern that many of these species will experience population declines and may even become extinct. This would lead to irreversible changes in the ecology of marine ecosystems by influencing community interactions and community structure. More recently, however, it has become apparent that taxa and species normally expected to be more tolerant of the projected changes may also be under threat. This realisation has come about because of recent examination of longer term responses to OA (weeks to months) in response to multiple variables i.e. usually OA plus temperature. It is now appears that organisms that are able to compensate physiologically and buffer the changes caused by environmental disruption, may be indirectly impacted by these environmental changes because such adjustments are ultimately energetically expensive. Currently, it is unknown what will happen to these organisms over time because the energy required for compensation could be diverted away from other vital processes such as immune function and growth, leading to increased susceptibilities to disease and a reduction in growth rates. The present project aims to establish links between compensatory capacities, energy use and performance in 2 species of brachyuran crabs with differing abilities to compensate for change. First year juvenile crabs from an ecologically important and highly invasive species outside of Europe, Carcinus maenas, and a commercially important species, Cancer pagurus, will be exposed to elevated pCO2 (0.08 kPa - levels predicted by 2100) and reduced salinity (~80%) for up to 18 months. The key physiological questions are whether the 2 species will be able to adjust their physiology to continue to function optimally, and whether these adjustments are metabolically costly and can be maintained over time. The key ecological questions will be whether these costly changes compromise individual fitness and performance with the potential to compromise population size. A project studentship will run in parallel to the main project and allow us to investigate the effects of high pCO2 and low salinity on the more vulnerable larval stages of three species of brachyuran crabs, C. maenas, C. pagurus and Necora puber. The studentship will investigate changes in larval development and performance which could impact larval recruitment, and will therefore identify potential population bottlenecks. This proposal represents the results of an on-going collaboration between researchers at Bangor and Southampton. These research teams are involved in a number of national and international OA research projects, but have identified that our limited understanding of the interaction of pCO2 and salinity, plus the lack of information on the responses of marine crustaceans to OA, is a weakness of existing research effort.