海水酸化及升温对刺参生长及能量收支的影响

以东亚浅海生态系统中的关键种——刺参(Apostichopus japonicus)为实验对象,研究了CO₂驱动的海水酸化及升温对其生长及能量收支的影响。实验设置对照组(大连近海水温, pCO₂ 400μatm)、升温组(大连近海水温+3℃, pCO₂ 400μatm)、酸化组(大连近海水温, pCO₂ 1100μatm)和酸化升温组(大连近海水温+3℃,pCO₂ 1100μatm)。结果表明:与对照组相比,温度升高3℃对刺参的生长无显著影响;酸化组刺参的特定生长率最低,较对照组降低0.19%/d,个体体重的变异系数最大;酸化升温组刺参的终末体重和特定生长率与对照组相较无显著差异,但其摄食率和排粪率均显著高于对照组。升温组和酸化组的刺参能量的分配模式与对照组相比未发生明显改变,但酸化升温组刺参的能量分配模式发生显著变化,其粪便能所占摄食能的比例显著升高。研究表明,海水酸化抑制了刺参的生长但未改变其能量的分配,生长的降低主要取决于摄食减少;而海水酸化与温度升高的共同作用可能会通过...     

光强调控三角褐指藻对海洋酸化的生理学响应

光和海洋酸化(CO₂浓度升高)分别对海洋硅藻的光合能力具有不同程度的影响, 但两者的耦合响应被较少关注。研究以三角褐指藻作为实验材料, 测定了不同光强下CO₂浓度升高对三角褐指藻的生长、净光合速率、生化组分、胞外碳酸酐酶(eCA)活性和核酮糖-1,5-二磷酸羧化/氧化酶(Rubisco)活性的影响。结果显示在低光下, CO₂浓度对三角褐指藻的生长和净光合速率(P_n)并没有显著影响, 而在高光下, 具有明显的影响。无论是在高光或是低光下, eCA活性、叶绿素和可溶性蛋白的含量都随着CO₂浓度的升高而降低。在低光下, 高浓度CO₂ (HC)培养下的Rubisco活性分别是低浓度CO₂ (LC)和中浓度CO₂ (MC)的2.42和1.39倍, 而在高光下, HC培养下的Rubisco活性分别是LC和MC的6.72和3.45倍。以上结果表明硅藻能够通过调节光合生理特征和CCM运行中能量的分配来适应环境中光强和CO₂浓度的变化。     

大气CO2增加对陆地生态系统微量气体地气交换的影响

简要综述了近年来国内外在大气CO₂浓度增加对微量气体交换影响方面的研究进展.首先介绍了有关大气CO₂浓度增加的研究技术和方法,比较了目前两种常用技术开顶箱(OTC)和开放式空气CO₂增加(FACE)方法的优缺点,然后着重阐述了用OTC和FACE研究陆地生态系统CH₄、N₂O、CO₂等微量气体的地气交换对大气CO₂浓度增加的响应.综合现有的资料表明,大气CO₂浓度增加,会促进绿色植物生物量增加,同时改变生物质的C/N比,降低有机质的分解速率,增强了陆地生态系统对大气CO₂的固持作用;大气CO₂浓度增加会提高产甲烷菌的活性和影响CH₄的排放过程,有可能导致湿地生态系统CH₄的排放增加;大气CO₂浓度增加对N₂O排放影响的研究较少,且尚无一致的结论.另外,对于其他微量气体,尚没有相关研究报道.鉴于此,今后应加强大气CO₂浓度增加的微量气体地气交换响应研究.     

不同CO2浓度下大豆叶片的光合生理生态特性

CO₂是光合作用的原料和底物,影响着光合作用的进程和光合产物的数量.利用Li-6400-40B同时测量大豆叶片在不同CO₂浓度(300、400、500和600 μmol·mol^-1)下的光合电子传递速率和光合作用对光的响应曲线,并用构建的光合作用对光响应机理模型拟合这些光响应曲线,获得大豆叶片一系列的光合参数、生理生态参数和捕光色素分子的物理参数.结果表明: 电子利用效率、最大电子传递速率和最大净光合速率随CO₂浓度的升高而增加;光补偿点和暗呼吸速率随CO₂浓度的升高而下降;光能利用效率和内禀(瞬时)水分利用效率随CO₂浓度的升高而增加,不同CO₂浓度下的最大光能利用效率和最大内禀(瞬时)水分利用效率之间存在显著差异,但不同CO₂浓度下的最大羧化效率的差异不显著.CO₂浓度的大小对光合作用中原初光反应存在一定程度的影响,即高CO₂浓度有利于减小捕光色素分子处于最低激发态的最小平均寿命,以提高光能传递的速度及增加大豆光合电子流的利用效率.     

不同CO2浓度下大豆叶片的光合生理生态特性

CO₂是光合作用的原料和底物,影响着光合作用的进程和光合产物的数量.利用Li-6400-40B同时测量大豆叶片在不同CO₂浓度(300、400、500和600 μmol·mol^-1)下的光合电子传递速率和光合作用对光的响应曲线,并用构建的光合作用对光响应机理模型拟合这些光响应曲线,获得大豆叶片一系列的光合参数、生理生态参数和捕光色素分子的物理参数.结果表明: 电子利用效率、最大电子传递速率和最大净光合速率随CO₂浓度的升高而增加;光补偿点和暗呼吸速率随CO₂浓度的升高而下降;光能利用效率和内禀(瞬时)水分利用效率随CO₂浓度的升高而增加,不同CO₂浓度下的最大光能利用效率和最大内禀(瞬时)水分利用效率之间存在显著差异,但不同CO₂浓度下的最大羧化效率的差异不显著.CO₂浓度的大小对光合作用中原初光反应存在一定程度的影响,即高CO₂浓度有利于减小捕光色素分子处于最低激发态的最小平均寿命,以提高光能传递的速度及增加大豆光合电子流的利用效率.     

不同土壤水分条件下CO2浓度对禾谷缢管蚜种群的影响

利用开顶式熏气室研究了不同土壤水分条件下不同CO₂浓度对禾谷缢管蚜种群的影响,以期对未来大气CO₂浓度升高条件下不同降雨地区的小麦蚜虫关系发展趋势做出初步预测.结果表明,随CO₂浓度升高,禾谷缢管蚜种群持续增长,但以CO₂浓度从350μl·L^-1上升到550μl·L^-1时增长最快;禾谷缢管蚜种群大小与土壤水分密切相关,各CO₂浓度下均以60%土壤水分的最大;当CO₂浓度从350μl·L^-1上升到550μl·L^-1时,60%土壤水分下的种群增长最快;当CO₂浓度从550μl·L^-1上升到700μl·L^-1时,60%和40%土壤水分下的种群增长相近,且高于80%土壤水分下的增长.据此可以认为,随大气CO₂浓度升高,禾谷缢管蚜种群会持续增长,从目前至下世纪中叶的时间内可能是蚜虫种群增长最快的阶段,特别在干旱、半干旱地区禾谷缢管蚜种群增长幅度较大、小麦受害较重.     

2020—2050年CO2施肥效应促进全球陆地生态系统碳吸收

CO₂施肥效应是全球变绿的主要原因,随着大气中CO₂浓度的持续增加,预估未来气候变化条件下,CO₂施肥效应对陆地生态系统的影响对减缓全球气候变化具有重大意义。基于未来气候情景数据和Farquhar模型,并结合生态过程模型BEPS(Boreal Ecosystem Productivity Simulator),定量化研究2020—2050年CO₂施肥效应对全球叶面积指数(LAI)和总初级生产力(GPP)的影响。研究结果显示2020—2050年,在RCP2.6、RCP4.5和RCP8.5气候情景下,CO₂施肥效应导致的LAI年际变化趋势分别为0.002、0.003和0.005 m^-2m^-2a^-1;三个气候情景下CO₂施肥效应对LAI的影响为CO₂每增加0.1%,LAI平均增加约8.1%—9.2%,由此导致GPP对应增加7.9%—14.6%;由CO₂施...     

Impacts of elevated carbon dioxide concentration on terrestrial ecosystems: problems and prospective

理解生态系统对过去、现在和未来CO₂浓度变化的响应,对于在生态进化的时间尺度上认识和预测全球变化的后果至关重要。过去三十多年来CO₂浓度升高相关的科学问题主要集中在对植物生长和生产力的影响, 碳氮周转, 生态系统渐进式氮限制(PNL)形成, 与其他胁迫因子(O₃污染、氮沉降、升温、干旱)之间的交互作用等方面。尽管生态学家在数据累积、基础理论上取得了一定进展, 但是仍然存在较大不确定性和大量未知有待解决。该文探究了近30年来CO₂浓度升高对陆地生态系统影响研究的国际研究进展、重点领域及热点, 回顾了CO₂浓度升高对植物影响的模拟实验研究发展, 重点论述了CO₂浓度升高对粮食产量及品质、碳固定、水分利用效率、生态系统氮利用和土壤微生物响应等国际前沿动态研究中存在的主要问题与不足, 在此基础上展望了未来研究中值得关注的前沿研究方向。     

土壤CO2浓度的动态观测、模拟和应用

土壤CO₂浓度不仅是地上、地下生物活动的反映,其变化对未来大气CO₂浓度和气候变化也有重要影响.本文综述了国内外土壤CO₂浓度的原位测定方法及其优缺点,分析了不同时(昼夜、几天、季节、年际)空(剖面、立地、景观)尺度上土壤CO₂浓度的变化规律和影响因素,概括了现有土壤CO₂浓度的模拟模型和发展态势,并总结了土壤CO₂浓度梯度法在土壤呼吸研究中的应用和限制因素.最后展望了未来有待研究的4个领域：1)研发适于恶劣土壤环境(如淹水、石质土)的土壤CO₂气体采集、测定技术;2)探讨土壤CO₂浓度对天气变化的响应及其调控机理;3)加强土壤CO₂浓度空间异质性的研究;4)扩大通量梯度法在热带、亚热带土壤呼吸测定中的应用.     

CO2 stimulation and response mechanisms vary with light supply in boreal conifers

北方针叶树CO₂ 的刺激和响应机制随光强而变化 黑云杉(Picea mariana [Mill.] B.S.P.)和白云杉(Picea glauca [Moench] Voss.)是同属物种,两者都是适度耐阴,并且在北美北方针叶林中广泛分布。为了了解光照对CO₂ 浓度升高的生理生态反应的影响,在三种光照条件下(温室中光照设置为100%、50%和30%)将一年生的两种幼苗暴露在360和720 µmol mol^–1 浓度的CO₂环境中,测定了其中后期叶面气体交换量。研究结果表明,CO₂的浓度升高提高了净光合速率 (P_n)和光合水分利用效率,但降低了气孔导度和蒸腾作用。CO₂对光合作用的刺激在50%光照下最大, 在100%光照下最小。光合作用、最大羧化速率(V_cmax)和光饱和电子传递速率(J_max)均随光照强度的 降低而降低。升高的CO₂在所有光照处理中显著降低了V_cmax,在生长季节中期,两种云杉的V_cmax均显著 降低,但在生长季节后期,当光照达到30%时,这一影响变得不明显,而且黑云杉的响应大于白云杉。CO₂ 浓度升高也降低了白云杉的J_max,但在生长季后期30%光照时,这种影响变得不显著。但CO₂ 浓度升高对 黑云杉的影响随时间而变化。在所有光照处理中,CO₂ 浓度升高降低了黑云杉生长中期的J_max,且在生长后 期30%光照时影响不显著,但在100%和50%光照时,J_max升高。这些研究结果表明,两个树种植物都受益于CO₂ 浓度的升高,但它们的响应机制随着光照的增加而变化：即在100%和50%光照下,它们的响应主要是生理上的,而在30%光照下,它们的响应主要是形态上的。     

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.     

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.     

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.     

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.     

Ocean acidification alters temperature and salinity preferences in larval fish

Ocean acidification alters the way in which animals perceive and respond to their world by affecting a variety of senses such as audition, olfaction, vision and pH sensing. Marine species rely on other senses as well, but we know little of how these might be affected by ocean acidification. We tested whether ocean acidification can alter the preference for physicochemical cues used for dispersal between ocean and estuarine environments. We experimentally assessed the behavioural response of a larval fish (Lates calcarifer) to elevated temperature and reduced salinity, including estuarine water of multiple cues for detecting settlement habitat. Larval fish raised under elevated CO₂ concentrations were attracted by warmer water, but temperature had no effect on fish raised in contemporary CO₂ concentrations. In contrast, contemporary larvae were deterred by lower salinity water, where CO₂-treated fish showed no such response. Natural estuarine water—of higher temperature, lower salinity, and containing estuarine olfactory cues—was only preferred by fish treated under forecasted high CO₂ conditions. We show for the first time that attraction by larval fish towards physicochemical cues can be altered by ocean acidification. Such alterations to perception and evaluation of environmental cues during the critical process of dispersal can potentially have implications for ensuing recruitment and population replenishment. Our study not only shows that freshwater species that spend part of their life cycle in the ocean might also be affected by ocean acidification, but that behavioural responses towards key physicochemical cues can also be negated through elevated CO₂ from human emissions.     

Ocean acidification boosts reproduction in fish via indirect effects

Ocean acidification affects species populations and biodiversity through direct negative effects on physiology and behaviour. The indirect effects of elevated CO₂ are less well known and can sometimes be counterintuitive. Reproduction lies at the crux of species population replenishment, but we do not know how ocean acidification affects reproduction in the wild. Here, we use natural CO₂ vents at a temperate rocky reef and show that even though ocean acidification acts as a direct stressor, it can indirectly increase energy budgets of fish to stimulate reproduction at no cost to physiological homeostasis. Female fish maintained energy levels by compensation: They reduced activity (foraging and aggression) to increase reproduction. In male fish, increased reproductive investment was linked to increased energy intake as mediated by intensified foraging on more abundant prey. Greater biomass of prey at the vents was linked to greater biomass of algae, as mediated by a fertilisation effect of elevated CO₂ on primary production. Additionally, the abundance and aggression of paternal carers were elevated at the CO₂ vents, which may further boost reproductive success. These positive indirect effects of elevated CO₂ were only observed for the species of fish that was generalistic and competitively dominant, but not for 3 species of subordinate and more specialised fishes. Hence, species that capitalise on future resource enrichment can accelerate their reproduction and increase their populations, thereby altering species communities in a future ocean.

Ocean acidification affects species populations and diversity through direct negative effects on physiology and behavior, but the indirect effects are less clear. Using volcanic carbon dioxide vents as natural analogues of future ocean acidification, this study shows that elevated CO2 can stimulate fish reproduction in the wild through increased food abundance, leading to increased energy budgets at no cost to physiological homeostasis.     

Effects of acidification on olfactory-mediated behaviour in freshwater and marine ecosystems: a synthesis

For many aquatic organisms, olfactory-mediated behaviour is essential to the maintenance of numerous fitness-enhancing activities, including foraging, reproduction and predator avoidance. Studies in both freshwater and marine ecosystems have demonstrated significant impacts of anthropogenic acidification on olfactory abilities of fish and macroinvertebrates, leading to impaired behavioural responses, with potentially far-reaching consequences to population dynamics and community structure. Whereas the ecological impacts of impaired olfactory-mediated behaviour may be similar between freshwater and marine ecosystems, the underlying mechanisms are quite distinct. In acidified freshwater, molecular change to chemical cues along with reduced olfaction sensitivity appear to be the primary causes of olfactory-mediated behavioural impairment. By contrast, experiments simulating future ocean acidification suggest that interference of high CO₂ with brain neurotransmitter function is the primary cause for olfactory-mediated behavioural impairment in fish. Different physico-chemical characteristics between marine and freshwater systems are probably responsible for these distinct mechanisms of impairment, which, under globally rising CO₂ levels, may lead to strikingly different consequences to olfaction. While fluctuations in pH may occur in both freshwater and marine ecosystems, marine habitat will remain alkaline despite future ocean acidification caused by globally rising CO₂ levels. In this synthesis, we argue that ecosystem-specific mechanisms affecting olfaction need to be considered for effective management and conservation practices.     

An Integrated Assessment Model for Helping the United States Sea Scallop (Placopecten magellanicus) Fishery Plan Ahead for Ocean Acidification and Warming

Ocean acidification, the progressive change in ocean chemistry caused by uptake of atmospheric CO₂, is likely to affect some marine resources negatively, including shellfish. The Atlantic sea scallop (Placopecten magellanicus) supports one of the most economically important single-species commercial fisheries in the United States. Careful management appears to be the most powerful short-term factor affecting scallop populations, but in the coming decades scallops will be increasingly influenced by global environmental changes such as ocean warming and ocean acidification. In this paper, we describe an integrated assessment model (IAM) that numerically simulates oceanographic, population dynamic, and socioeconomic relationships for the U.S. commercial sea scallop fishery. Our primary goal is to enrich resource management deliberations by offering both short- and long-term insight into the system and generating detailed policy-relevant information about the relative effects of ocean acidification, temperature rise, fishing pressure, and socioeconomic factors on the fishery using a simplified model system. Starting with relationships and data used now for sea scallop fishery management, the model adds socioeconomic decision making based on static economic theory and includes ocean biogeochemical change resulting from CO₂ emissions. The model skillfully reproduces scallop population dynamics, market dynamics, and seawater carbonate chemistry since 2000. It indicates sea scallop harvests could decline substantially by 2050 under RCP 8.5 CO₂ emissions and current harvest rules, assuming that ocean acidification affects P. magellanicus by decreasing recruitment and slowing growth, and that ocean warming increases growth. Future work will explore different economic and management scenarios and test how potential impacts of ocean acidification on other scallop biological parameters may influence the social-ecological system. Future empirical work on the effect of ocean acidification on sea scallops is also needed.     

Going with the flow: the role of ocean circulation in global marine ecosystems under a changing climate

Ocean warming, acidification, deoxygenation and reduced productivity are widely considered to be the major stressors to ocean ecosystems induced by emissions of CO₂. However, an overlooked stressor is the change in ocean circulation in response to climate change. Strong changes in the intensity and position of the western boundary currents have already been observed, and the consequences of such changes for ecosystems are beginning to emerge. In this study, we address climatically induced changes in ocean circulation on a global scale but relevant to propagule dispersal for species inhabiting global shelf ecosystems, using a high‐resolution global ocean model run under the IPCC RCP 8.5 scenario. The ¼ degree model resolution allows improved regional realism of the ocean circulation beyond that of available CMIP5‐class models. We use a Lagrangian approach forced by modelled ocean circulation to simulate the circulation pathways that disperse planktonic life stages. Based on trajectory backtracking, we identify present‐day coastal retention, dominant flow and dispersal range for coastal regions at the global scale. Projecting into the future, we identify areas of the strongest projected circulation change and present regional examples with the most significant modifications in their dominant pathways. Climatically induced changes in ocean circulation should be considered as an additional stressor of marine ecosystems in a similar way to ocean warming or acidification.     

Antagonistic effects of ocean acidification and warming on hunting sharks

Ocean warming and acidification alter the physiological performance and behaviour of many small‐bodied fishes, yet the potential interactive effects of these stressors on larger predators remains poorly understood. In particular, the combined effects of elevated temperature on metabolism and of elevated CO₂ on the behaviour of large predators may not only affect their foraging behaviour, but also the communities in which their prey live. We used a factorial design to assess how projected warming and acidification create synergies or antagonisms between physiological and behavioural processes, such as swimming activity and feeding behaviour through odour tracking and vision. Temperature increased swimming activity during feeding, independent of CO₂. Although temperature also increased motivational drive to locate and accept prey, elevated CO₂ negated chemical and visual behavioural responses that enable effective hunting. Fundamental to these effects was the negligible effect of high CO₂ in isolation, but its power to negate the positive effects of temperature when brought in conjunction. The reduced potential to locate prey due to the interactive effects of ocean acidification and warming, in combination with increases in energetic demand, suggests that energetic tradeoffs will be needed for sharks to sustain themselves at an individual and population level in a future ocean.