Assessing the effects of long-term ocean acidification at volcanic CO2 vents

目的：确定沿海生境二氧化碳浓度升高的生态效应。在CNRS Roscoff和MBA普利茅斯为期8个月的培训期间，学生将监测岩石池栖息地的碳酸盐化学和生物群的变化。学生将接受一个监督团队的培训，该团队在使用天然类似物进行基于生态系统的海洋酸化研究方面处于世界领先地位。然后，学生将应用这些技能来监测Pantelleria和Vulcano(西西里)附近沿海生境的pH(总规模)和海水碳酸盐化学(DIC和总碱度)的时空变化，那里的气体喷口很浅(&lt；10米深)，海岸线的平均二氧化碳水平为380,1000和2000 ppm，类似于PI Off Ischia最近在《自然》杂志上所描述的。这些气体喷口地点经过仔细选择，适合检验以下假设；1)近期水平的海洋酸化(公元2100年情景)可能会促进自然环境中海草和某些入侵大型藻类的生长和繁殖，2)慢性高碳酸血症可能导致海底生物多样性的全面减少，包括大量钙化物种的丧失，对潮间带和潮下生境的生态系统功能产生负面影响，3)移植实验，加上沿二氧化碳梯度的采样，证实了一些物种可以通过改变骨骼矿物学来适应长期的酸化，4)活跃的后生动物(例如虾和鱼)能够承受成年后高水平的二氧化碳，但不能在自然酸化的地点完成其生活史。这种方法是创新的，因为生态系统影响很难使用国际生物圈行动计划和EPOCA计划采用的方法进行评估，即在数周至数月的时间尺度上对水族箱和中层生态系统的二氧化碳水平进行控制。该项目旨在满足英国开放存取科学计划的要求，该计划规定，“对二氧化碳天然富集区的研究也可以获得强有力的见解”。学员资格涉及目标3.1、3.3，并将获得数据，以改善我们对具有商业重要性的物种的OA影响的理解。首席导师是EPOCA项目中的一名PI，并与人合著了《海洋酸化研究最佳实践指南》，这将是本次学习的方法论基础。将使用手持沉积物中的岩芯(例如有孔虫)和岩石上的0.5平方米样方，对从380到平均1000和2000ppm二氧化碳的重复地块上的海底生物多样性和生物量进行比较。将部署沉降板来研究不同二氧化碳水平下的招募过程，并将利用移植实验(珊瑚藻类、贻贝和牡蛎)来确定长期暴露在高二氧化碳水平下对钙化、繁殖力和生长的影响。光合作用(使用PAM)、繁殖和生长将测量海草(Posidonia)和大型藻类(马尾藻、天冬)。这名学生将在Bijma的BIOACID小组中使用原子力和拉曼显微镜检查钙化的藻类、有孔虫和珊瑚是否能够根据周围海水中二氧化碳的量来适应它们的矿物学，以研究在高二氧化碳条件下生长的钙化生物的精细和超微结构的影响。在2012年实地考察期间，将使用重复的视觉计数来评估虾和鱼的多样性、行为和丰度，记录与二氧化碳监测区有关的怀孕雌性和鱼巢的分布，因为幼体阶段可能最容易受到OA影响。考虑到我们的监督记录、对Vulcano和Pantelleria的初步调查以及我们在Ischia的经验，需要测试的假设范围对于博士研究来说并不是太雄心勃勃。

Objective: to determine the ecological effects of elevated CO2 levels in coastal habitats. In an 8 month training period at CNRS Roscoff and the MBA Plymouth the student will monitor variations in carbonate chemistry and biota of rockpool habitats. The student will be trained by a supervisory team that is world-leading in ecosystem based ocean acidification research using natural analogues. The student will then apply these skills to monitor spatial and temporal variability in pH (Total Scale) and seawater carbonate chemistry (DIC and total alkalinity) on coastal habitats off Pantelleria and Vulcano (Sicily) where gas vents are shallow (<10 m depth) and have shorelines with mean pCO2 levels of 380, 1000 and 2000 ppm, similar to those recently described in Nature by the PI off Ischia. These gas vent sites have been chosen carefully and are suited to test the following hypotheses; 1) near-future levels of ocean acidification (year 2100 scenarios) may enhance the growth and reproduction of sea grasses and certain invasive macroalgae in natural settings, 2) chronic hypercapnia can lead to an overall reduction in benthic biodiversity, including the loss of numerous calcified species, with negative effects on ecosystem function in intertidal and subtidal habitats, 3) transplant experiments, coupled with sampling along pCO2 gradients, confirm that some species can adapt to long-term acidification by altering skeletal mineralogy, 4) active metazoans (e.g. shrimp and fish) can withstand high levels of CO2 as adults but do not complete their life-histories at naturally acidified sites. This approach is innovative as ecosystem effects are difficult to assess using methods adopted by the BIOACID and EPOCA programmes, whereby CO2 levels are manipulated in aquaria and mesocosms over timescales of weeks-months. This studentship is designed to meet the UK OA Science Plan which states that 'Powerful insights may also be gained from studies of areas with natural CO2 enrichment'. The studentship addresses Aims 3.1, 3.3 and will also obtain data to improve our understanding of OA impacts for commercially important species. The lead supervisor is a PI within the EPOCA program and co-author of their 'Guide to Best Practices in Ocean Acidification Research' which will be the methodological basis of this studentship. Comparisons will be made of benthic biodiversity and biomass on replicate plots from 380 to mean 1000 and 2000 ppm CO2 using hand-held cores in sediments (e.g. for foraminifera) and 0.5 m2 quadrats on rock. Settlement plates will be deployed to investigate recruitment processes at different levels of pCO2 and transplant experiments (of coralline algae, mussels and oysters) will be used to determine the effects of long-term exposures to high CO2 levels on calcification, fecundity and growth. Photosynthesis (using PAM), reproduction and growth will be measured on seagrass (Posidonia) and macroalgae (Sargassum, Asparagopsis). The student will examine whether calcified algae, foraminifera and corals can adapt their mineralogy depending on the amounts of CO2 in the surrounding seawater under supervision in Bijma's BIOACID group using Atomic force- and Raman-microscopy to study the impact on the fine- and ultra-structure of calcified organisms that grew at high CO2. During field excursions in 2012 repeated visual counts will be used to assess the diversity, behavior and abundance of shrimps and fish recording the distribution of gravid females and fish nests in relation to CO2 monitoring zones, as juvenile stages can be the most vulnerable to OA effects. The range of hypotheses to be tested are not too ambitions for doctoral research, given our supervisory track-record, preliminary surveys of Vulcano and Pantelleria and our experience at Ischia.