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。

Effects and mechanisms of CO2-driven ocean acidification on marine fish behavior: A review

Since the industrial revolution, the atmospheric carbon dioxide (CO₂) concentration has increased by approximately 40%, mainly due to anthropogenic activities (e.g., burning of fossil fuel). Approximately one third of CO₂ released into the atmosphere is eventually absorbed by ocean, lowering the pH of surface seawater and causing wholesale shifts in seawater carbonate chemistry, a phenomenon known as "ocean acidification" (OA). During the past 250 years, the average surface seawater pH has decreased by approximately 0.1 units, from 8.21 to 8.10. According to the prediction of Intergovernmental Panel on Climate Change (IPCC), the average surface seawater pH will decline to 7.7-7.8 by the end of the 21^st century and 7.3-7.4 around 2300. Behavior, the first response exhibited by fish to stimulus, plays important roles in fish reproduction, predation, and anti-predation. Therefore, effects of OA on marine fish behavior has, recently, garnered considerable attention and gradually become a new research hotspot. Although not immediately lethal, OA has been demonstrated to adversely influence marine fish behavior, especially their predation, anti-predation, behavioral lateralization, shoaling behavior, and habitat detection and seeking behavior, by disrupting sensory system, interfering with GABA_A-receptor function, and hindering cell signal transduction. Behavior normality is likely to impair fitness and population survival, which will in turn affect species interactions and ecological processes, and subsequently pose a great threat to ecosystem structure and functioning. However, current knowledge on marine fish behavior modification is mostly obtained by laboratory simulation and restricted to single species, life stage, leading to an incomplete view of how OA and other coinciding environmental stressors can affect the ecological interactions that structure biological communities. More importantly, China has a long coastline, vast sea area, abundant fish resources, and developed fishing and aquaculture industry; however, only few studies in China have focused on fish behavior alteration under near future OA scenarios. These, undoubtedly, limit our ability to precisely forecast the potential risk of ecosystem in a rapidly changing marine environment, and deal with OA. We therefore reviewed published literature on marine fish behavior under OA conditions, synthesized current understanding and identified knowledge gaps of how OA might affect marine fish behavior, assessed the potential ecological risk, and discussed the underlying mechanisms. Finally, key suggestions have been provided to facilitate future studies, especially those in China.