海洋酸化生态学研究进展

工业革命以来,人类排放的大量二氧化碳引起温室效应的同时,也被海洋吸收使得全球海洋出现了严重的酸化。海洋酸化及伴随的海水碳酸盐化学体系的变化对海洋生物产生深远的影响。以海洋酸化对钙化作用和光合作用的影响为重点,总结了近年来关于海洋酸化的研究,介绍了海洋中不同生态系统对海洋酸化的响应。一方面,海水中CO23-浓度和碳酸钙饱和度的降低对海洋钙化生物造成严重损害,生活在高纬的冷水珊瑚和翼足目等文石生产者是最早的受害者;贝类和棘皮动物在钙化早期对海洋酸化尤其敏感,其幼体存活率受到海洋酸化的严重制约。另一方面,CO2浓度的增加能促进海洋植物的光合作用和生长,增加初级生产力,改变浮游植物的群落组成。此外,海洋酸化可以促进固氮和脱氮作用同时削弱硝化作用,改变溶氧浓度分布和金属的生物可利用性,从而对海洋生物产生间接影响。海洋酸化对海洋生态系统的影响机制复杂,影响程度深远。为了能准确的评估海洋酸化的生态学效应,需要更全面深入的研究。     

海洋酸化和全球变暖对贝类生理生态的影响研究进展

研究表明海洋酸化和全球变暖已严重威胁到海洋生态系统稳的定性及生物多样性。由于人类活动,大气中不断增加的CO2不仅造成全球气候异常,而且大量的CO2被海洋吸收,造成了海水中H+浓度增加,即海洋酸化(Ocean Acidification)。海洋酸化严重影响海洋生物的生存和繁衍,尤其是有壳类生物,如贝类,甲壳类,棘皮类等。主要影响方面包括生物的产卵受精,孵化,早期发育,钙化,酸碱调节,免疫功能,蛋白质合成,基因表达,摄食及能量代谢等一系列和生理相关的机能,进而对个体行为学,种群结构和海洋生态系统造成严重危害。目前,已有大量海洋酸化对海洋贝类的生理生态影响的报道,与此同时,全球变暖导致海洋温度升高伴随着海洋酸化同步发生。因此,为了更加准确地预测海洋生物应对全球气候变化的生理生态应答,越来越多的学者开始致力于研究温度和海洋酸化的复合胁迫对海洋生物交互影响作用。综述了近年来海洋酸化对贝类生理生态的影响,主要从个体早期发育、钙化、免疫、繁殖等方面做了系统的阐述,还对酸化和温度对贝类的复合环境胁迫效应也做了综合分析,以期为今后的海洋酸化研究提供基础理论。     

海洋酸化影响硅藻固碳相关基因表达的研究进展

由于人类活动导致的大气CO2浓度升高,将导致海水p H值下降,从而引起海洋酸化,改变海水碳酸盐系统,影响海洋生物的生长、发育、代谢、凋亡及钙化过程等。研究海洋酸化对藻类固碳途径(生物碳泵)的影响对了解和预测未来海洋碳泵的发展趋势具有重要意义,硅藻作为海洋初级生产力的主要生产者,研究海洋酸化影响其固碳过程的意义更大。尽管目前已对海洋酸化影响硅藻的生理生化过程有了较为深入的研究,但从基因表达水平上研究海洋酸化对硅藻固碳过程的影响还较少,本文对此领域做一概述。     

基于文献计量的全球海洋酸化研究状况分析

海洋酸化(Ocean acidification)为目前备受人们关注的全球性问题。因此为了能够客观地揭示海洋酸化的研究态势,研究采用文献计量分析(Bibliometric analysis)的方法,以海洋酸化概念提出后(2004年以后)ISI Web of Science期刊引文数据库中涉及到海洋酸化研究的所有文献为样本,对文献的增长趋势及期刊分布进行描述统计,并基于关键词的知识图谱及突变分析的方法探究海洋酸化的热点关注方向随时间的变动及研究前沿。描述统计表明:海洋酸化概念提出的这十多年来,涉及海洋酸化的研究文献数量呈现激增的态势,研究学科交叉明显,海洋酸化对珊瑚礁的影响是这十年来的重点研究领域。从基于关键词的知识图谱可以看到,在海洋酸化研究初期(2004—2009年),研究内容主要分为两个部分,一是海洋酸化对海洋生物(尤其是珊瑚礁生物及浮游植物)及生态系统的影响;二是对海洋酸化现象的认识;中期(2010—2015年),研究内容与初期相似,研究重点往海洋生物上倾斜,同时有新的热点研究区域和研究方向的出现;近期(2016年以后),海洋酸化对海洋生物影响的研究依旧占据着主流研究方向。对基于突变分析得到的当前(2018年2月)海洋酸化研究的热点关注的文献分析发现,当前海洋酸化的研究存在以下5个前沿方向:(1)在探究海洋酸化与生物的关系之时需结合多因子讨论;(2)探索生物在海洋酸化下的内在应对机制;(3)海洋酸化影响下的生物响应的综合评估及预测;(4)探索海洋酸化对海洋生态系统的影响;(5)对海洋酸化概念的挑战——海洋酸化形成原因的探索。     

海洋酸化条件下Cd2+和Hg2+对斧文蛤幼贝急性毒性效应

为研究在海洋酸化条件下重金属污染物对滩涂贝类的影响,采用半静态急性毒性实验的研究方法,利用海洋酸化人工模拟系统,分析了不同酸化条件下(对照组pH 8.20、酸化组pH分别为7.80、7.60和7.40)Cd2+和Hg2+对斧文蛤(Meretrix lamarckii)幼贝急性毒性效应的影响。实验结果表明:在实验设定的海洋酸化范围内,单一的海洋酸化对斧文蛤幼贝的存活没有显著性影响,但海洋酸化显著增强了Cd2+和Hg2+的急性毒性。与对照组相比,酸化组Cd2+和Hg2+的毒性随着酸化程度的加剧而呈现出逐渐增强的趋势; Cd2+和Hg2+均在pH 7.40时对斧文蛤的毒性最强,其96h半致死(96h LC50)浓度分别为4.068 mg/L(Cd2+)和10.332 mg/L(Hg2+),明显低于pH 8.20、7.80和7.60时其对斧文蛤幼贝的96h LC50浓度(其值分别为Cd2+ 6.458、5.947、4.728 mg/L和Hg2+ 12.027、11.169、10.595 mg/L)。研究有助于丰富海洋酸化与重金属毒理作用在海洋贝类中的研究内容,为斧文蛤资源恢复和海洋环境保护提供科学依据。     

外套膜转录物组分析揭示尿素在贻贝耐受海水酸化中的作用

海洋酸化是目前地球面临的主要环境问题之一,对海洋矿化生物的生存带来严重威胁。贝类是目前海水养殖的主要物种,海洋酸化会对贝壳的生物矿化过程产生抑制,因而对贝类养殖业的发展带来严重影响。前期研究中已发现,尿素对贻贝贝壳的形成具有辅助作用,推测尿素有助于贻贝在海洋酸化背景下的生存。为进一步探究尿素通过何种分子机制对贻贝耐受海洋酸化产生积极影响,以厚壳贻贝外套膜为研究对象,采用转录物组学策略分析了尿素添加对贻贝外套膜组织在酸化海水中的基因表达量变化的影响。结果表明,尿素添加对贻贝外套膜在酸化条件下的转录物组变化具有逆转趋势,可抑制外套膜中受酸化胁迫而激活的细胞自噬、凋亡、以及免疫应激相关通路;同时,也诱导了部分贝壳基质蛋白质表达量的上调,从而有助于维持贻贝在酸化条件下的生物矿化过程。上述研究有助于了解贻贝对海洋酸化的耐受性机制,也为后续贝类养殖业在海洋酸化背景下的健康发展提供了新的思路。     

马鞍列岛海洋牧场褐菖鲉的摄食习性

海洋牧场是近岸渔业资源保护和恢复的有效途径,为评估海洋牧场建设对岩礁性鱼类的影响,本文基于马鞍列岛海洋牧场建设前后资源调查数据,利用胃含物分析和稳定同位素测试,研究了褐菖鲉的摄食习性.结果表明:海洋牧场建设前褐菖鲉主要摄食端足类、蟹类和头足类,优势饵料生物种类为麦秆虫、日本枪乌贼、日本蟳、日本岩瓷蟹和滩栖阳遂足等.随体长的增大,蟹类的比例增加,而端足类的比例减少.洋牧场建设后褐菖鲉主要摄食蟹类、端足类和鱼类,优势饵料生物种类为双斑蟳、日本蟳、麦秆虫和赤鼻棱鳀等.随体长的增大,鱼类和蟹类的比例增加,而端足类的比例先增加后减少.根据稳定同位素分析结果,海洋牧场区褐菖鲉可以划分为体长<10.0 cm、10.0～13.9.0 cm和≥14.0 cm 3个摄食群体,平均营养级为3.40级.     

海洋酸化对海洋无脊椎动物的影响研究进展

人源二氧化碳(CO2)的大量排放,导致空气中CO2浓度越来越高,其中大约1/4至1/3被海洋吸收。过多CO2在海水中的溶解,除引起海水p H值降低外,还导致海水中碳酸盐平衡体系的变化,即"海洋酸化"现象。很多海洋无脊椎动物不但在海洋生态系统中发挥重要作用,还是重要的水产养殖种,因此具有重要的生态与经济价值。由于海洋无脊椎动物的生活史在海水中完成,因此海洋环境的变化极易对其造成影响。大量研究已证实海洋酸化能对多种海洋无脊椎动物的受精、发育、生物钙化、基因表达等生命活动产生显著影响。综述了近年来海洋酸化对海洋无脊椎动物影响研究的相关报道,归纳了其对海洋无脊椎动物不同生命活动的影响,分析了其生态学效应,探讨了现有研究在方法创新、内容拓展以及机理分析等方面存在的局限与不足,并展望了海洋酸化对海洋无脊椎动物影响研究的发展方向。     

鱼类对海洋升温与酸化的响应

自工业革命以来,空气中人为排放CO₂量增加,引起温室效应,导致地球表面温度升高和海水升温;同时,由于海-气界面气体交换,大气中CO₂部分溶解于海洋,引起海洋酸化。海洋升温加快鱼体内生化反应和代谢速率,并通过影响生长、觅食和繁殖等生命过程中能量供给,间接影响到鱼类种群分布、群落结构及生态系统的功能。而海水酸化会干扰海洋鱼类仔稚鱼的感觉和行为,增加其被捕食率,并削弱其野外生存能力,可能威胁自然种群补给量。综述了海洋升温、海洋酸化及其两者共同作用对海洋鱼类的影响,为预测鱼类响应全球海洋环境变化的响应趋势提供相关依据。     

海洋酸化效应对海水鱼类的综合影响评述

人类活动引起的大气CO2浓度的升高,除了使全球温度升高外,导致的另一个严重生态问题——海洋酸化(Ocean acidification,OA),受到社会各界包括科研界的高度重视,该领域的大部分研究结果都是在近十年才发表出来的,目前还有很多需要解决的问题。海洋酸化的研究涉及到很多学科的交叉包括化学、古生物学、生态学、生物地球化学等等。在生物学领域,海洋酸化主要围绕敏感物种,例如由碳酸钙形成贝壳或外骨骼的贝类,珊瑚礁群体等。鱼类作为海洋脊椎动物的代表生物类群,自身具有一定的酸碱平衡调节能力,但相关海洋酸化方向的研究并不是很多。尽管人们对于海洋酸化对鱼类的影响了解甚少,这并不说明海洋酸化对鱼类没有作用或者效应小,在相关研究逐步展开的同时,发现鱼类同样受到海洋酸化的危害,几乎涉及到鱼类整个生活史和几乎大部分生理过程,尤其是早期生活史的高度敏感。因此就目前国内外对此领域研究结果做综述,以期待业界同行能够对海水鱼类这个大的类群引起重视。     

Ocean acidification impairs crab foraging behaviour

Anthropogenic elevation of atmospheric CO₂ is driving global-scale ocean acidification, which consequently influences calcification rates of many marine invertebrates and potentially alters their susceptibility to predation. Ocean acidification may also impair an organism''s ability to process environmental and biological cues. These counteracting impacts make it challenging to predict how acidification will alter species interactions and community structure. To examine effects of acidification on consumptive and behavioural interactions between mud crabs (Panopeus herbstii) and oysters (Crassostrea virginica), oysters were reared with and without caged crabs for 71 days at three pCO₂ levels. During subsequent predation trials, acidification reduced prey consumption, handling time and duration of unsuccessful predation attempt. These negative effects of ocean acidification on crab foraging behaviour more than offset any benefit to crabs resulting from a reduction in the net rate of oyster calcification. These findings reveal that efforts to evaluate how acidification will alter marine food webs should include quantifying impacts on both calcification rates and animal behaviour.     

Effects of Ocean Acidification on Juvenile Red King Crab (Paralithodes camtschaticus) and Tanner Crab (Chionoecetes bairdi) Growth,Condition, Calcification,and Survival

Ocean acidification, a decrease in the pH in marine waters associated with rising atmospheric CO₂ levels, is a serious threat to marine ecosystems. In this paper, we determine the effects of long-term exposure to near-future levels of ocean acidification on the growth, condition, calcification, and survival of juvenile red king crabs, Paralithodes camtschaticus, and Tanner crabs, Chionoecetes bairdi. Juveniles were reared in individual containers for nearly 200 days in flowing control (pH 8.0), pH 7.8, and pH 7.5 seawater at ambient temperatures (range 4.4–11.9 °C). In both species, survival decreased with pH, with 100% mortality of red king crabs occurring after 95 days in pH 7.5 water. Though the morphology of neither species was affected by acidification, both species grew slower in acidified water. At the end of the experiment, calcium concentration was measured in each crab and the dry mass and condition index of each crab were determined. Ocean acidification did not affect the calcium content of red king crab but did decrease the condition index, while it had the opposite effect on Tanner crabs, decreasing calcium content but leaving the condition index unchanged. This suggests that red king crab may be able to maintain calcification rates, but at a high energetic cost. The decrease in survival and growth of each species is likely to have a serious negative effect on their populations in the absence of evolutionary adaptation or acclimatization over the coming decades.     

Meta-analysis reveals negative yet variable effects of ocean acidification on marine organisms

Ocean acidification is a pervasive stressor that could affect many marine organisms and cause profound ecological shifts. A variety of biological responses to ocean acidification have been measured across a range of taxa, but this information exists as case studies and has not been synthesized into meaningful comparisons amongst response variables and functional groups. We used meta-analytic techniques to explore the biological responses to ocean acidification, and found negative effects on survival, calcification, growth and reproduction. However, there was significant variation in the sensitivity of marine organisms. Calcifying organisms generally exhibited larger negative responses than non-calcifying organisms across numerous response variables, with the exception of crustaceans, which calcify but were not negatively affected. Calcification responses varied significantly amongst organisms using different mineral forms of calcium carbonate. Organisms using one of the more soluble forms of calcium carbonate (high-magnesium calcite) can be more resilient to ocean acidification than less soluble forms (calcite and aragonite). Additionally, there was variation in the sensitivities of different developmental stages, but this variation was dependent on the taxonomic group. Our analyses suggest that the biological effects of ocean acidification are generally large and negative, but the variation in sensitivity amongst organisms has important implications for ecosystem responses.     

海水酸化及升温对刺参稚参生长和变色的影响

海洋酸化和海洋变暖是当下及未来海洋生物及其依存生态系统面临的主要环境压力和生态问题。当前,海洋生物早期发育气候变化生物学的研究主要集中于海洋酸化的影响,为了更好地探究海洋气候变化对海洋生物的影响,有必要研究海洋酸化和变暖联合作用下海洋生物的生态响应。以受精后24天的刺参稚参为研究对象,通过模拟当前和本世纪末海洋环境,观察海水酸化和升温对刺参稚参在体色发育关键时期生长、发育及体色变化的影响。实验设置对照组(大连近海水温,pCO2400 mg·kg^-1)、升温组(对照组水温+2℃,pCO2400 mg·kg^-1)、酸化组(对照组水温,pCO21000 mg·kg^-1)、酸化升温组(对照组水温+2℃,pCO21000 mg·kg^-1)。结果表明:温度升高2℃能够显著提高稚参发育速率,体色变化加快;pH值降低0.23个单位显著延迟稚参生长,体色变化减缓,个体间体重差异变大;升温2℃能抵消pH降低0.23个单位对稚参生长和发育的负面影响;较长时间的海水酸化和升温胁迫能够使稚参逐渐适应,稚参表现出一定的耐受性。     

Temperature and CO2 additively regulate physiology,morphology and genomic responses of larval sea urchins,Strongylocentrotus purpuratus

Ocean warming and ocean acidification, both consequences of anthropogenic production of CO₂, will combine to influence the physiological performance of many species in the marine environment. In this study, we used an integrative approach to forecast the impact of future ocean conditions on larval purple sea urchins (Strongylocentrotus purpuratus) from the northeast Pacific Ocean. In laboratory experiments that simulated ocean warming and ocean acidification, we examined larval development, skeletal growth, metabolism and patterns of gene expression using an orthogonal comparison of two temperature (13°C and 18°C) and pCO₂ (400 and 1100 μatm) conditions. Simultaneous exposure to increased temperature and pCO₂ significantly reduced larval metabolism and triggered a widespread downregulation of histone encoding genes. pCO₂ but not temperature impaired skeletal growth and reduced the expression of a major spicule matrix protein, suggesting that skeletal growth will not be further inhibited by ocean warming. Importantly, shifts in skeletal growth were not associated with developmental delay. Collectively, our results indicate that global change variables will have additive effects that exceed thresholds for optimized physiological performance in this keystone marine species.     

Effects of ocean acidification on Antarctic marine organisms: A meta‐analysis

Southern Ocean waters are among the most vulnerable to ocean acidification. The projected increase in the CO₂ level will cause changes in carbonate chemistry that are likely to be damaging to organisms inhabiting these waters. A meta‐analysis was undertaken to examine the vulnerability of Antarctic marine biota occupying waters south of 60°S to ocean acidification. This meta‐analysis showed that ocean acidification negatively affects autotrophic organisms, mainly phytoplankton, at CO₂ levels above 1,000 μatm and invertebrates above 1,500 μatm, but positively affects bacterial abundance. The sensitivity of phytoplankton to ocean acidification was influenced by the experimental procedure used. Natural, mixed communities were more sensitive than single species in culture and showed a decline in chlorophyll a concentration, productivity, and photosynthetic health, as well as a shift in community composition at CO₂ levels above 1,000 μatm. Invertebrates showed reduced fertilization rates and increased occurrence of larval abnormalities, as well as decreased calcification rates and increased shell dissolution with any increase in CO₂ level above 1,500 μatm. Assessment of the vulnerability of fish and macroalgae to ocean acidification was limited by the number of studies available. Overall, this analysis indicates that many marine organisms in the Southern Ocean are likely to be susceptible to ocean acidification and thereby likely to change their contribution to ecosystem services in the future. Further studies are required to address the poor spatial coverage, lack of community or ecosystem‐level studies, and the largely unknown potential for organisms to acclimate and/or adapt to the changing conditions.     

海洋酸化对珊瑚礁生态系统的影响研究进展

目前,大气CO2浓度的升高已导致海水pH值比工业革命前下降了约0.1,海水碳酸盐平衡体系随之变化,进而影响珊瑚礁生态系统的健康。近年来的研究表明海洋酸化导致造礁石珊瑚幼体补充和群落恢复更加困难,造礁石珊瑚和其它造礁生物(Reef-building organisms)钙化率降低甚至溶解,乃至影响珊瑚礁鱼类的生命活动。虽然海洋酸化对造礁石珊瑚光合作用的影响不显著,但珊瑚-虫黄藻共生体系会受到一定影响。建议选择典型海区进行长期系统监测,结合室内与原位模拟试验,从个体、种群、群落到系统不同层面,运用生理学和分子生物学技术,结合生态学研究手段,综合研究珊瑚的相应响应,以期深入认识海洋酸化对珊瑚礁生态系统健康(例如珊瑚白化)的影响及其效应。