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。     

海洋酸化对蟹类影响的研究进展

人类活动排放二氧化碳引起了海水碳酸盐平衡体系变化和pH下降, 最终导致了“海洋酸化”。海洋酸化对蟹类产生了从表观到分子的多重影响。文章在总结海洋酸化对各种蟹类生长发育、生理与代谢、表型和行为等方面影响的基础上, 对其影响的机理展开了讨论, 并对控制海洋酸化及其对蟹类的影响研究提出了意见和建议。     

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。     

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。     

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。     

海洋酸化条件下铜、镉对日本虎斑猛水蚤的急性毒性效应

以日本虎斑猛水蚤(Tigriopus japonicus)为试验生物,采用高纯度CO2和空气的混合气体调配试验所需酸化海水(pH值7.70、7.30、6.50),研究不同海水酸化条件下铜、镉对海洋生物的急性毒性效应。结果表明:单一CO2酸化海水对日本虎斑猛水蚤存活的影响不显著;海水酸化对铜和镉急性毒性的影响效应有差异。铜在低pH值(6.5)时对日本虎斑猛水蚤的毒性最强,96h LC50浓度为0.64 mg/L,明显低于pH值为8.0、7.7、7.3对日本虎斑猛水蚤的96h LC50浓度,其分别为1.98,1.19,1.05 mg/L,随pH值下降,96h LC50下降了近3倍。海水酸化使镉的96h LC50略呈下降趋势,但对其急性毒性影响效应并不显著;pH值为7.7和7.3时,铜的安全浓度分别为11.9、10.5μg/L,接近于中国海水二类水质标准。本研究表明随着海洋酸化的进程我国近海水域将面临铜污染加剧的威胁。     

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。     

海洋酸化对马氏珠母贝胚胎和早期幼虫发育的影响

研究当前预测2100年海洋将达到的酸化程度对马氏珠母贝(Pinctada martensii)胚胎和早期幼虫发育的影响.人工受精卵置于pH=7.70的CO2酸化海水(酸化组)和pH=8.10的对照海水(对照组)中进行胚胎和幼虫发育试验.结果表明:人工受精8 h后,酸化组和对照组胚胎在各发育时期的数量分布没有明显的差异;24 h后,酸化组16.6%±12.0%发育至D型幼虫,且畸形个体百分比为48.2%±9.1%;而对照组44.8%±7.4%发育至D型幼虫,畸形个体百分比仅为18.6%±11.5%.48 h后,酸化组D型幼虫百分比23.0%±9.6%.畸形个体比例高达63.2%±14.1%;对照组D型幼虫59.4%±13.0%,畸形个体百分比仅为26.6%±14.5%;与对照组相比,酸化组中D型幼虫壳长和壳高明显偏小,而且壳长增长缓慢.试验表明,将来马氏珠母贝这类发生生物钙化的典型热带海洋贝类生物,其幼虫发育将会受到海洋酸化的不利影响.     

Ocean acidification alters zooplankton communities and increases top‐down pressure of a cubozoan predator

The composition of local ecological communities is determined by the members of the regional community that are able to survive the abiotic and biotic conditions of a local ecosystem. Anthropogenic activities since the industrial revolution have increased atmospheric CO₂ concentrations, which have in turn decreased ocean pH and altered carbonate ion concentrations: so called ocean acidification (OA). Single‐species experiments have shown how OA can dramatically affect zooplankton development, physiology and skeletal mineralization status, potentially reducing their defensive function and altering their predatory and antipredatory behaviors. This means that increased OA may indirectly alter the biotic conditions by modifying trophic interactions. We investigated how OA affects the impact of a cubozoan predator on their zooplankton prey, predominantly Copepoda, Pleocyemata, Dendrobranchiata, and Amphipoda. Experimental conditions were set at either current (pCO₂ 370 μatm) or end‐of‐the‐century OA (pCO₂ 1,100 μatm) scenarios, crossed in an orthogonal experimental design with the presence/absence of the cubozoan predator Carybdea rastoni. The combined effects of exposure to OA and predation by C. rastoni caused greater shifts in community structure, and greater reductions in the abundance of key taxa than would be predicted from combining the effect of each stressor in isolation. Specifically, we show that in the combined presence of OA and a cubozoan predator, populations of the most abundant member of the zooplankton community (calanoid copepods) were reduced 27% more than it would be predicted based on the effects of these stressors in isolation, suggesting that OA increases the susceptibility of plankton to predation. Our results indicate that the ecological consequences of OA may be greater than predicted from single‐species experiments, and highlight the need to understand future marine global change from a community perspective.     

Individual and interactive effects of ocean acidification,global warming,and UV radiation on phytoplankton

Rising carbon dioxide (CO₂) concentrations in the atmosphere result in increasing global temperatures and ocean warming (OW). Concomitantly, dissolution of anthropogenic CO₂ declines seawater pH, resulting in ocean acidification (OA) and altering marine chemical environments. The marine biological carbon pump driven by marine photosynthesis plays an important role for oceanic carbon sinks. Therefore, how ocean climate changes affect the amount of carbon fixation by primary producers is closely related to future ocean carbon uptake. OA may upregulate metabolic pathways in phytoplankton, such as upregulating ß-oxidation and the tricarboxylic acid cycle, resulting in increased accumulation of toxic phenolic compounds. Ocean warming decreases global phytoplankton productivity; however, regionally, it may stimulate primary productivity and change phytoplankton community composition, due to different physical and chemical environmental requirements of species. It is still controversial how OA and OW interactively affect marine carbon fixation by photosynthetic organisms. OA impairs the process of calcification in calcifying phytoplankton and aggravate ultraviolet (UV)-induced harms to the cells. Increasing temperatures enhance the activity of cellular repair mechanisms, which mitigates UV-induced damage. The effects of OA, warming, enhanced exposure to UV-B as well as the interactions of these environmental stress factors on phytoplankton productivity and community composition, are discussed in this review.     

CO2-induced ocean acidification increases anxiety in Rockfish via alteration of GABAA receptor functioning

The average surface pH of the ocean is dropping at a rapid rate due to the dissolution of anthropogenic CO₂, raising concerns for marine life. Additionally, some coastal areas periodically experience upwelling of CO₂-enriched water with reduced pH. Previous research has demonstrated ocean acidification (OA)-induced changes in behavioural and sensory systems including olfaction, which is due to altered function of neural gamma-aminobutyric acid type A (GABA_A) receptors. Here, we used a camera-based tracking software system to examine whether OA-dependent changes in GABA_A receptors affect anxiety in juvenile Californian rockfish (Sebastes diploproa). Anxiety was estimated using behavioural tests that measure light/dark preference (scototaxis) and proximity to an object. After one week in OA conditions projected for the next century in the California shore (1125 ± 100 µatm, pH 7.75), anxiety was significantly increased relative to controls (483 ± 40 µatm CO₂, pH 8.1). The GABA_A-receptor agonist muscimol, but not the antagonist gabazine, caused a significant increase in anxiety consistent with altered Cl⁻ flux in OA-exposed fish. OA-exposed fish remained more anxious even after 7 days back in control seawater; however, they resumed their normal behaviour by day 12. These results show that OA could severely alter rockfish behaviour; however, this effect is reversible.     

Calcification, growth and mortality of juvenile clams Ruditapes decussatus under increased pCO2 and reduced pH: Variable responses to ocean acidification at local scales?

We investigated the effects of ocean acidification on juvenile clams Ruditapes decussatus (average shell length 10.24 mm) in a controlled CO₂ perturbation experiment. The carbonate chemistry of seawater was manipulated by diffusing pure CO₂, to attain two reduced pH levels (by −0.4 and −0.7 pH units), which were compared to unmanipulated seawater. After 75 days we found no differences among pH treatments in terms of net calcification, size or weight of the clams. The naturally elevated total alkalinity of local seawater probably contributed to buffer the effects of increased pCO₂ and reduced pH. Marine organisms may, therefore, show diverse responses to ocean acidification at local scales, particularly in coastal, estuarine and transitional waters, where the physical-chemical characteristics of seawater are most variable. Mortality was significantly reduced in the acidified treatments. This trend was probably related to the occurrence of spontaneous spawning events in the control and intermediate acidification treatments. Spawning, which was unexpected due to the small size of the clams, was not observed for the pH −0.7 treatment, suggesting that the increased survival under acidified conditions may have been associated with a delay in the reproductive cycle of the clams. Future research about the impacts of ocean acidification on marine biodiversity should be extended to other types of biological and ecological processes, apart from biological calcification.     

Elevated CO2 affects embryonic development and larval phototaxis in a temperate marine fish

As an effect of anthropogenic CO₂ emissions, the chemistry of the world's oceans is changing. Understanding how this will affect marine organisms and ecosystems are critical in predicting the impacts of this ongoing ocean acidification. Work on coral reef fishes has revealed dramatic effects of elevated oceanic CO₂ on sensory responses and behavior. Such effects may be widespread but have almost exclusively been tested on tropical reef fishes. Here we test the effects elevated CO₂ has on the reproduction and early life history stages of a temperate coastal goby with paternal care by allowing goby pairs to reproduce naturally in an aquarium with either elevated (ca 1400 μatm) CO₂ or control seawater (ca 370 μatm CO₂). Elevated CO₂ did not affect the occurrence of spawning nor clutch size, but increased embryonic abnormalities and egg loss. Moreover, we found that elevated CO₂ significantly affected the phototactic response of newly hatched larvae. Phototaxis is a vision‐related fundamental behavior of many marine fishes, but has never before been tested in the context of ocean acidification. Our findings suggest that ocean acidification affects embryonic development and sensory responses in temperate fishes, with potentially important implications for fish recruitment.     

Elevated CO2 impairs olfactory‐mediated neural and behavioral responses and gene expression in ocean‐phase coho salmon (Oncorhynchus kisutch)

Elevated concentrations of CO₂ in seawater can disrupt numerous sensory systems in marine fish. This is of particular concern for Pacific salmon because they rely on olfaction during all aspects of their life including during their homing migrations from the ocean back to their natal streams. We investigated the effects of elevated seawater CO₂ on coho salmon (Oncorhynchus kisutch) olfactory‐mediated behavior, neural signaling, and gene expression within the peripheral and central olfactory system. Ocean‐phase coho salmon were exposed to three levels of CO₂, ranging from those currently found in ambient marine water to projected future levels. Juvenile coho salmon exposed to elevated CO₂ levels for 2 weeks no longer avoided a skin extract odor that elicited avoidance responses in coho salmon maintained in ambient CO₂ seawater. Exposure to these elevated CO₂ levels did not alter odor signaling in the olfactory epithelium, but did induce significant changes in signaling within the olfactory bulb. RNA‐Seq analysis of olfactory tissues revealed extensive disruption in expression of genes involved in neuronal signaling within the olfactory bulb of salmon exposed to elevated CO₂, with lesser impacts on gene expression in the olfactory rosettes. The disruption in olfactory bulb gene pathways included genes associated with GABA signaling and maintenance of ion balance within bulbar neurons. Our results indicate that ocean‐phase coho salmon exposed to elevated CO₂ can experience significant behavioral impairments likely driven by alteration in higher‐order neural signal processing within the olfactory bulb. Our study demonstrates that anadromous fish such as salmon may share a sensitivity to rising CO₂ levels with obligate marine species suggesting a more wide‐scale ecological impact of ocean acidification.     

Coralline algal structure is more sensitive to rate,rather than the magnitude,of ocean acidification

Marine pCO₂ enrichment via ocean acidification (OA), upwelling and release from carbon capture and storage (CCS) facilities is projected to have devastating impacts on marine biomineralisers and the services they provide. However, empirical studies using stable endpoint pCO₂ concentrations find species exhibit variable biological and geochemical responses rather than the expected negative patterns. In addition, the carbonate chemistry of many marine systems is now being observed to be more variable than previously thought. To underpin more robust projections of future OA impacts on marine biomineralisers and their role in ecosystem service provision, we investigate coralline algal responses to realistically variable scenarios of marine pCO₂ enrichment. Coralline algae are important in ecosystem function; providing habitats and nursery areas, hosting high biodiversity, stabilizing reef structures and contributing to the carbon cycle. Red coralline marine algae were exposed for 80 days to one of three pH treatments: (i) current pH (control); (ii) low pH (7.7) representing OA change; and (iii) an abrupt drop to low pH (7.7) representing the higher rates of pH change observed at natural vent systems, in areas of upwelling and during CCS releases. We demonstrate that red coralline algae respond differently to the rate and the magnitude of pH change induced by pCO₂ enrichment. At low pH, coralline algae survived by increasing their calcification rates. However, when the change to low pH occurred at a fast rate we detected, using Raman spectroscopy, weaknesses in the calcite skeleton, with evidence of dissolution and molecular positional disorder. This suggests that, while coralline algae will continue to calcify, they may be structurally weakened, putting at risk the ecosystem services they provide. Notwithstanding evolutionary adaptation, the ability of coralline algae to cope with OA may thus be determined primarily by the rate, rather than magnitude, at which pCO₂ enrichment occurs.     

Metabolically induced pH fluctuations by some coastal calcifiers exceed projected 22nd century ocean acidification: a mechanism for differential susceptibility?

Anthropogenically mediated decreases in pH, termed ocean acidification (OA), may be a major threat to marine organisms and communities. Research has focussed mainly on tropical coral reefs, but temperate reefs play a no less important ecological role in colder waters, where OA effects may first be manifest. Herein, we report that trends in pH at the surface of three ecologically important cold‐water calcifiers (a primary producer and herbivores), under a range of fluid flows, differ substantially from one another, and for two of the three calcifiers, the pH, during darkness, is lower than the mean projected pH due to OA for the surface waters of the global ocean beyond the year 2100. Using micro‐electrodes, we show that each calcifier had a different pH gradient between its surface and mainstream seawater, i.e. within the diffusion boundary layer (DBL) that appears to act as an environmental buffer to mainstream pH. Abalone encountered only mainstream seawater pH, whereas pH at the sea urchins’ surface was reduced by ~0.35 units. For coralline algae, pH was ~0.5 units higher in the light and ~0.35 units lower under darkness than in ambient mainstream seawater. This wide range of pH within the DBL of some calcifiers will probably affect their performance under projected future reductions in pH due to OA. Differing exposure to a range of surface pH may result in differential susceptibility of calcifiers to OA. Such fluctuations are no doubt regulated by the interplay of water movement, morphology and metabolic rates (e.g. respiration, calcification and/or photosynthesis). Our study, by considering physics (flow regime), chemistry (pH gradients vs. OA future projections) and biology (trophic level, physiology and morphology), reveals that predicting species‐specific responses and subsequent ecosystem restructuring to OA is complex and requires a holistic, eco‐mechanical, approach.     

Ocean acidification and responses to predators: can sensory redundancy reduce the apparent impacts of elevated CO2 on fish?

Carbon dioxide (CO₂) levels in the atmosphere and surface ocean are rising at an unprecedented rate due to sustained and accelerating anthropogenic CO₂ emissions. Previous studies have documented that exposure to elevated CO₂ causes impaired antipredator behavior by coral reef fish in response to chemical cues associated with predation. However, whether ocean acidification will impair visual recognition of common predators is currently unknown. This study examined whether sensory compensation in the presence of multiple sensory cues could reduce the impacts of ocean acidification on antipredator responses. When exposed to seawater enriched with levels of CO₂ predicted for the end of this century (880 μatm CO₂), prey fish completely lost their response to conspecific alarm cues. While the visual response to a predator was also affected by high CO_2, it was not entirely lost. Fish exposed to elevated CO_2, spent less time in shelter than current‐day controls and did not exhibit antipredator signaling behavior (bobbing) when multiple predator cues were present. They did, however, reduce feeding rate and activity levels to the same level as controls. The results suggest that the response of fish to visual cues may partially compensate for the lack of response to chemical cues. Fish subjected to elevated CO₂ levels_, and exposed to chemical and visual predation cues simultaneously, responded with the same intensity as controls exposed to visual cues alone. However, these responses were still less than control fish simultaneously exposed to chemical and visual predation cues. Consequently, visual cues improve antipredator behavior of CO₂ exposed fish, but do not fully compensate for the loss of response to chemical cues. The reduced ability to correctly respond to a predator will have ramifications for survival in encounters with predators in the field, which could have repercussions for population replenishment in acidified oceans.