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.     

珊瑚礁生态系统病毒研究进展

病毒对珊瑚礁生态系统中的生物进化、生物地球化学循环、珊瑚疾病等方面具有重要的生态影响。随着珊瑚礁的全球性退化,病毒在珊瑚礁生态系统中的功能与危害日益显现。综述了珊瑚礁生态系统中病毒的研究现状与进展,包括：（1）珊瑚礁病毒的多样性与分布特征（水体、宿主、核心病毒组）;（2）珊瑚礁病毒的生态功能（感染方式、促进生物进化、生物地球化学循环）;（3）珊瑚礁病毒对全球气候变化的响应（热压力、珊瑚疾病）。总体而言,珊瑚礁生态系统具有极高的病毒多样性,所发现的60个科占已知所有病毒科数量的58%。珊瑚的核心病毒组主要由双链DNA病毒、单链DNA病毒、单链逆转录病毒所组成,珊瑚黏液层对病毒具有富集作用。"Piggyback-the-Winner"（依附-胜利）是病毒在珊瑚礁中主要的生物动力学模式,其可通过水平基因迁移的方式促进礁区生物进化。病毒可通过裂解细菌与浮游藻类的途径参与珊瑚礁的生物地球化学循环,尤其是碳循环与氮循环过程。此外,病毒还具有介导珊瑚热白化与直接引发珊瑚疾病的能力,这会影响珊瑚礁生态系统应对气候变化的适应性与恢复力。基于国际上的研究进展综述,结合南海珊瑚礁生态现状提出以下研究方向,以期促进我国珊瑚礁病毒学的发展：（1）开展南海珊瑚礁中病毒多样性的识别及其时-空分布特征研究;（2）探索病毒对南海珊瑚热白化、珊瑚疾病的介导作用及其与气候变化的关系;（3）揭示病毒对南海珊瑚礁生物地球化学循环的贡献。     

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。     

海洋酸化对海洋鱼类行为的影响及机制研究进展

自工业革命以来,在人类活动的影响下,大气CO_2浓度持续增加,其中有大约1/3被海洋吸收,造成海水pH值降低和碳酸盐平衡体系的波动,即"海洋酸化"现象(Ocean Acidification)。据联合国政府间气候变化专门委员会预测,如果以当前速率排放CO_2,到21世纪末表层海水的pH值将降低至7.7—7.8,而到2300年将降低至7.3—7.4。作为鱼类对外界刺激最直接的反应,行为在鱼类的繁衍、捕食、避敌等过程中发挥着关键作用。基于此,海洋酸化对海洋鱼类行为的影响受到了越来越多关注。现有研究结果显示海洋酸化不仅会显著干扰包括嗅觉、听觉、视觉在内的感官功能,还将对神经生理功能和细胞信号传导等过程产生不利影响,从而影响海洋鱼类的捕食、逃避捕食、行为侧向化、栖息地识别与选择和集群等行为。行为异常将直接损害鱼类种群的生存与繁衍,继而威胁海洋生态系统的稳定和功能。我国海岸线漫长,海域辽阔,鱼类资源丰富,鱼类捕捞和养殖业发达。但与国外相比,国内此类研究十分匮乏,仅见零星报道。这种现状极大的制约了我国相关应对策略的制定,对我国海洋生态保育和渔业发展非常不利。此外,当前的研究也存在研究范围窄、研究手段不合理、行为效应、潜在机制及生态风险考察不足、研究结果难以整合等问题亟待改进。为此,研究对国内外相关研究进展进行了梳理和总结,并对未来的研究进行展望,以期弥补上述缺憾,促进国内相关研究的广泛开展。     

珊瑚礁生态系统初级生产力研究进展

珊瑚礁生态系统由珊瑚礁生物群落及其周围的海洋环境共同组成。该生态系统具有很高的生产力和生物多样性而引起科学家的重视 ,特别是高初级生产力。初级生产力的贡献者包括底栖植物、浮游植物、共生藻和自养细菌等。初级生产力的测定方法较多 ,各有利弊 ,通常采用 1 4C同位素法。在初级生产力中 ,新生产力更引起科学界关注。对于新生产力的测定 ,主要应用 1 5N示踪法 ,采用“f”比或 Redfield比值来估算。为了减少误差 ,一般同时使用几种方法。光是影响初级生产力的主要因素 ,而对新生产力构成限制的主要因素是氮源。珊瑚礁生态系统初级生产力研究较多 ,但新生产力却很少。未来科学界研究重点在于珊瑚礁生态系统初级生产力和新生产力的动力学效应     

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。     

海洋酸化对泥蚶精子运动的影响及作用机理初探

研究分析了未来海洋酸化情景(pH7.8和pH7.4)对典型滩涂贝类泥蚶(Tegillarca granosa)精子运动活力的影响,并从精子运动供能角度探究了其作用机理。研究结果表明,海洋酸化可以显著削弱泥蚶的精子运动速度。由于精子的三磷酸腺苷(ATP)水平与其活力呈显著的正相关,研究检测了不同酸化条件下泥蚶精子的ATP含量及其合成关键酶酶活,实验结果显示精子的ATP含量以及磷酸果糖激酶和丙酮酸激酶活力在酸化条件下均显著下降。此外,精子内的Ca2+-ATP酶(Ca2+-ATPase)调节了精子的运动能力,因此实验也探究了海洋酸化对泥蚶精子Ca2+-ATPase酶活的影响,结果证实该酶活力在海水pH为7.4时被显著抑制。综合本研究结果可以得出,海洋酸化很可能会通过干扰精子细胞内ATP的合成及Ca2+的调控进而削弱精子的运动速度。     

Future habitat suitability for coral reef ecosystems under global warming and ocean acidification

Rising atmospheric CO₂ concentrations are placing spatially divergent stresses on the world's tropical coral reefs through increasing ocean surface temperatures and ocean acidification. We show how these two stressors combine to alter the global habitat suitability for shallow coral reef ecosystems, using statistical Bioclimatic Envelope Models rather than basing projections on any a priori assumptions of physiological tolerances or fixed thresholds. We apply two different modeling approaches (Maximum Entropy and Boosted Regression Trees) with two levels of complexity (one a simplified and reduced environmental variable version of the other). Our models project a marked temperature‐driven decline in habitat suitability for many of the most significant and bio‐diverse tropical coral regions, particularly in the central Indo‐Pacific. This is accompanied by a temperature‐driven poleward range expansion of favorable conditions accelerating up to 40–70 km per decade by 2070. We find that ocean acidification is less influential for determining future habitat suitability than warming, and its deleterious effects are centered evenly in both hemispheres between 5° and 20° latitude. Contrary to expectations, the combined impact of ocean surface temperature rise and acidification leads to little, if any, degradation in future habitat suitability across much of the Atlantic and areas currently considered ‘marginal’ for tropical corals, such as the eastern Equatorial Pacific. These results are consistent with fossil evidence of range expansions during past warm periods. In addition, the simplified models are particularly sensitive to short‐term temperature variations and their projections correlate well with reported locations of bleaching events. Our approach offers new insights into the relative impact of two global environmental pressures associated with rising atmospheric CO₂ on potential future habitats, but greater understanding of past and current controls on coral reef ecosystems is essential to their conservation and management under a changing climate.     

Vulnerability of global coral reef habitat suitability to ocean warming,acidification and eutrophication

Coral reefs are threatened by global and local stressors. Yet, reefs appear to respond differently to different environmental stressors. Using a global dataset of coral reef occurrence as a proxy for the long‐term adaptation of corals to environmental conditions in combination with global environmental data, we show here how global (warming: sea surface temperature; acidification: aragonite saturation state, Ω_arag) and local (eutrophication: nitrate concentration, and phosphate concentration) stressors influence coral reef habitat suitability. We analyse the relative distance of coral communities to their regional environmental optima. In addition, we calculate the expected change of coral reef habitat suitability across the tropics in relation to an increase of 0.1°C in temperature, an increase of 0.02 μmol/L in nitrate, an increase of 0.01 μmol/L in phosphate and a decrease of 0.04 in Ω_arag. Our findings reveal that only 6% of the reefs worldwide will be unaffected by local and global stressors and can thus act as temporary refugia. Local stressors, driven by nutrient increase, will affect 22% of the reefs worldwide, whereas global stressors will affect 11% of these reefs. The remaining 61% of the reefs will be simultaneously affected by local and global stressors. Appropriate wastewater treatments can mitigate local eutrophication and could increase areas of temporary refugia to 28%, allowing us to ‘buy time’, while international agreements are found to abate global stressors.     

Coral reef calcifiers buffer their response to ocean acidification using both bicarbonate and carbonate

Central to evaluating the effects of ocean acidification (OA) on coral reefs is understanding how calcification is affected by the dissolution of CO₂ in sea water, which causes declines in carbonate ion concentration [CO₃²⁻] and increases in bicarbonate ion concentration [HCO₃⁻]. To address this topic, we manipulated [CO₃²⁻] and [HCO₃⁻] to test the effects on calcification of the coral Porites rus and the alga Hydrolithon onkodes, measured from the start to the end of a 15-day incubation, as well as in the day and night. [CO₃²⁻] played a significant role in light and dark calcification of P. rus, whereas [HCO₃⁻] mainly affected calcification in the light. Both [CO₃²⁻] and [HCO₃⁻] had a significant effect on the calcification of H. onkodes, but the strongest relationship was found with [CO₃²⁻]. Our results show that the negative effect of declining [CO₃²⁻] on the calcification of corals and algae can be partly mitigated by the use of HCO₃⁻ for calcification and perhaps photosynthesis. These results add empirical support to two conceptual models that can form a template for further research to account for the calcification response of corals and crustose coralline algae to OA.     

Detrimental effects of ocean acidification on the economically important Mediterranean red coral (Corallium rubrum)

The mean predicted decrease of 0.3–0.4 pH units in the global surface ocean by the end of the century has prompted urgent research to assess the potential effects of ocean acidification on the marine environment, with strong emphasis on calcifying organisms. Among them, the Mediterranean red coral (Corallium rubrum) is expected to be particularly susceptible to acidification effects, due to the elevated solubility of its Mg‐calcite skeleton. This, together with the large overexploitation of this species, depicts a bleak future for this organism over the next decades. In this study, we evaluated the effects of low pH on the species from aquaria experiments. Several colonies of C. rubrum were long‐term maintained for 314 days in aquaria at two different pH levels (8.10 and 7.81, pH_T). Calcification rate, spicule morphology, major biochemical constituents (protein, carbohydrates and lipids) and fatty acids composition were measured periodically. Exposure to lower pH conditions caused a significant decrease in the skeletal growth rate in comparison with the control treatment. Similarly, the spicule morphology clearly differed between both treatments at the end of the experiment, with aberrant shapes being observed only under the acidified conditions. On the other hand, while total organic matter was significantly higher under low pH conditions, no significant differences were detected between treatments regarding total carbohydrate, lipid, protein and fatty acid composition. However, the lower variability found among samples maintained in acidified conditions relative to controls, suggests a possible effect of pH decrease on the metabolism of the colonies. Our results show, for the first time, evidence of detrimental ocean acidification effects on this valuable and endangered coral species.     

Persistent natural acidification drives major distribution shifts in marine benthic ecosystems

Ocean acidification is receiving increasing attention because of its potential to affect marine ecosystems. Rare CO₂ vents offer a unique opportunity to investigate the response of benthic ecosystems to acidification. However, the benthic habitats investigated so far are mainly found at very shallow water (less than or equal to 5 m depth) and therefore are not representative of the broad range of continental shelf habitats. Here, we show that a decrease from pH 8.1 to 7.9 observed in a CO₂ vent system at 40 m depth leads to a dramatic shift in highly diverse and structurally complex habitats. Forests of the kelp Laminaria rodriguezii usually found at larger depths (greater than 65 m) replace the otherwise dominant habitats (i.e. coralligenous outcrops and rhodolith beds), which are mainly characterized by calcifying organisms. Only the aragonite-calcifying algae are able to survive in acidified waters, while high-magnesium-calcite organisms are almost completely absent. Although a long-term survey of the venting area would be necessary to fully understand the effects of the variability of pH and other carbonate parameters over the structure and functioning of the investigated mesophotic habitats, our results suggest that in addition of significant changes at species level, moderate ocean acidification may entail major shifts in the distribution and dominance of key benthic ecosystems at regional scale, which could have broad ecological and socio-economic implications.     

Pacific-wide contrast highlights resistance of reef calcifiers to ocean acidification

Ocean acidification (OA) and its associated decline in calcium carbonate saturation states is one of the major threats that tropical coral reefs face this century. Previous studies of the effect of OA on coral reef calcifiers have described a wide variety of outcomes for studies using comparable partial pressure of CO₂ (pCO₂) ranges, suggesting that key questions remain unresolved. One unresolved hypothesis posits that heterogeneity in the response of reef calcifiers to high pCO₂ is a result of regional-scale variation in the responses to OA. To test this hypothesis, we incubated two coral taxa (Pocillopora damicornis and massive Porites) and two calcified algae (Porolithon onkodes and Halimeda macroloba) under 400, 700 and 1000 μatm pCO₂ levels in experiments in Moorea (French Polynesia), Hawaii (USA) and Okinawa (Japan), where environmental conditions differ. Both corals and H. macroloba were insensitive to OA at all three locations, while the effects of OA on P. onkodes were location-specific. In Moorea and Hawaii, calcification of P. onkodes was depressed by high pCO₂, but for specimens in Okinawa, there was no effect of OA. Using a study of large geographical scale, we show that resistance to OA of some reef species is a constitutive character expressed across the Pacific.     

The reef-building coral Siderastrea siderea exhibits parabolic responses to ocean acidification and warming

Anthropogenic increases in atmospheric CO₂ over this century are predicted to cause global average surface ocean pH to decline by 0.1–0.3 pH units and sea surface temperature to increase by 1–4°C. We conducted controlled laboratory experiments to investigate the impacts of CO₂-induced ocean acidification (pCO₂ = 324, 477, 604, 2553 µatm) and warming (25, 28, 32°C) on the calcification rate of the zooxanthellate scleractinian coral Siderastrea siderea, a widespread, abundant and keystone reef-builder in the Caribbean Sea. We show that both acidification and warming cause a parabolic response in the calcification rate within this coral species. Moderate increases in pCO₂ and warming, relative to near-present-day values, enhanced coral calcification, with calcification rates declining under the highest pCO₂ and thermal conditions. Equivalent responses to acidification and warming were exhibited by colonies across reef zones and the parabolic nature of the corals'' response to these stressors was evident across all three of the experiment''s 30-day observational intervals. Furthermore, the warming projected by the Intergovernmental Panel on Climate Change for the end of the twenty-first century caused a fivefold decrease in the rate of coral calcification, while the acidification projected for the same interval had no statistically significant impact on the calcification rate—suggesting that ocean warming poses a more immediate threat than acidification for this important coral species.     

Framework of barrier reefs threatened by ocean acidification

To date, studies of ocean acidification (OA) on coral reefs have focused on organisms rather than communities, and the few community effects that have been addressed have focused on shallow back reef habitats. The effects of OA on outer barrier reefs, which are the most striking of coral reef habitats and are functionally and physically different from back reefs, are unknown. Using 5‐m long outdoor flumes to create treatment conditions, we constructed coral reef communities comprised of calcified algae, corals, and reef pavement that were assembled to match the community structure at 17 m depth on the outer barrier reef of Moorea, French Polynesia. Communities were maintained under ambient and 1200 μatm pCO₂ for 7 weeks, and net calcification rates were measured at different flow speeds. Community net calcification was significantly affected by OA, especially at night when net calcification was depressed ~78% compared to ambient pCO₂. Flow speed (2–14 cm s^?1) enhanced net calcification only at night under elevated pCO₂. Reef pavement also was affected by OA, with dissolution ~86% higher under elevated pCO₂ compared to ambient pCO₂. These results suggest that net accretion of outer barrier reef communities will decline under OA conditions predicted within the next 100 years, largely because of increased dissolution of reef pavement. Such extensive dissolution poses a threat to the carbonate foundation of barrier reef communities.     

Coral reef calcification: carbonate,bicarbonate and proton flux under conditions of increasing ocean acidification

Data on calcification rate of coral and crustose coralline algae were used to test the proton flux model of calcification. There was a significant correlation between calcification (G) and the ratio of dissolved inorganic carbon (DIC) to proton concentration ([DIC] : [H⁺] ratio). The ratio is tightly correlated with [CO₃²⁻] and with aragonite saturation state (Ω_a). An argument is presented that correlation does not prove cause and effect, and that Ω_a and [CO₃²⁻] have no basic physiological meaning on coral reefs other than a correlation with [DIC] : [H⁺] ratio, which is the driver of G.