Sundin Josefin, Amcoff Mirjam, Mateos-González Fernando, Raby Graham D, Jutfelt Fredrik, Clark Timothy D
Department of Neuroscience, Uppsala University, Uppsala, Sweden.
Department of Zoology/Functional Zoomorphology, Stockholm University, Stockholm, Sweden.
Behav Ecol Sociobiol. 2017;71(8):108. doi: 10.1007/s00265-017-2337-x. Epub 2017 Jul 5.
Levels of dissolved carbon dioxide (CO) projected to occur in the world's oceans in the near future have been reported to increase swimming activity and impair predator recognition in coral reef fishes. These behavioral alterations would be expected to have dramatic effects on survival and community dynamics in marine ecosystems in the future. To investigate the universality and replicability of these observations, we used juvenile spiny chromis damselfish () to examine the effects of long-term CO exposure on routine activity and the behavioral response to the chemical cues of a predator (). Commencing at 3-20 days post-hatch, juvenile damselfish were exposed to present-day CO levels (420 μatm) or to levels forecasted for the year 2100 (~1000 μatm) for 3 months of their development. Thereafter, we assessed routine activity before and after injections of seawater (sham injection, control) or seawater-containing predator chemical cues. There was no effect of CO treatment on routine activity levels before or after the injections. All fish decreased their swimming activity following the predator cue injection but not following the sham injection, regardless of CO treatment. Our results corroborate findings from a growing number of studies reporting limited or no behavioral responses of fishes to elevated CO.
Alarmingly, it has been reported that levels of dissolved carbon dioxide (CO) forecasted for the year 2100 cause coral reef fishes to be attracted to the chemical cues of predators. However, most studies have exposed the fish to CO for very short periods before behavioral testing. Using long-term acclimation to elevated CO and automated tracking software, we found that fish exposed to elevated CO showed the same behavioral patterns as control fish exposed to present-day CO levels. Specifically, activity levels were the same between groups, and fish acclimated to elevated CO decreased their swimming activity to the same degree as control fish when presented with cues from a predator. These findings indicate that behavioral impacts of elevated CO levels are not universal in coral reef fishes.
据报道，预计在不久的将来世界海洋中溶解二氧化碳（CO₂）的水平会增加珊瑚礁鱼类的游泳活动并损害其对捕食者的识别能力。预计这些行为改变将对未来海洋生态系统的生存和群落动态产生巨大影响。为了研究这些观察结果的普遍性和可重复性，我们使用幼年多棘雀鲷（Acanthochromis polyacanthus）来检验长期暴露于CO₂对其日常活动以及对捕食者（褐菖鲉Sebastes inermis）化学信号的行为反应的影响。从孵化后约3至20天开始，幼年雀鲷在其发育的3个月中暴露于当前的CO₂水平（约420微大气压）或预测的2100年水平（约1000微大气压）。此后，我们在注射海水（假注射，对照）或含捕食者化学信号的海水之前和之后评估日常活动。CO₂处理对注射前后的日常活动水平没有影响。无论CO₂处理如何，所有鱼类在注射捕食者信号后都会降低游泳活动，但在假注射后则不会。我们的结果证实了越来越多的研究结果，这些研究报告鱼类对升高的CO₂的行为反应有限或没有反应。
令人担忧的是，据报道，预测的2100年溶解二氧化碳（CO₂）水平会使珊瑚礁鱼类被捕食者的化学信号所吸引。然而，大多数研究在行为测试前将鱼类暴露于CO₂的时间非常短。通过长期适应升高的CO₂并使用自动跟踪软件，我们发现暴露于升高的CO₂的鱼类表现出与暴露于当前CO₂水平的对照鱼类相同的行为模式。具体而言，各组之间的活动水平相同，并且当接触到捕食者的信号时，适应升高的CO₂的鱼类与对照鱼类一样程度地降低了它们的游泳活动。这些发现表明，升高的CO₂水平对珊瑚礁鱼类的行为影响并不普遍。
