Zakroff Casey J, Mooney T Aran
Biology Department, Woods Hole Oceanographic Institution, Woods Hole, MA, United States.
Massachusetts Institute of Technology-Woods Hole Oceanographic Institution Joint Program in Oceanography/Applied Ocean Science and Engineering, Cambridge, MA, United States.
Front Physiol. 2020 May 20;11:501. doi: 10.3389/fphys.2020.00501. eCollection 2020.
Ocean acidification (OA) and warming seas are significant concerns for coastal systems and species. The Atlantic longfin squid, , a core component of the Northwest Atlantic trophic web, has demonstrated impacts, such as reduced growth and delayed development, under high chronic exposure to acidification (2200 ppm), but the combined effects of OA and warming have not been explored in this species. In this study, egg capsules were reared under a combination of several acidification levels (400, 2200, and 3500 ppm) and temperatures (20 and 27°C). Hatchlings were measured for a range of metrics [dorsal mantle length (DML), yolk sac volume (YV), malformation, and hatching success] in three trials over the 2016 breeding season (May - October). Although notable resistance to stressors was seen, highlighting variability within and between clutches, reduced DML and malformation of the embryos occurred at the highest OA exposure. Surprisingly, increased temperatures did not appear to exacerbate OA impacts, although responses were variable. Time to hatching, which increased with acidification, decreased much more drastically under warming and, further, decreased or removed delays caused by acidification. Hatching success, while variable by clutch, showed consistent patterns of greater late stage loss of embryos under acidification and greater early stage loss under warming, highlighting the potential difference in timing between these stressors for this system, i.e., that acidification stress builds up and causes impacts over time within the egg capsule as the embryos grow and respire. High OA-exposed hatchlings from the warmer conditions often showed reduced impacts compared to those reared in ambient temperatures. This may be due to the increased developmental rate and subsequently reduced OA exposure time of embryos in the higher temperature treatment. These results indicate a substantive potential plasticity to multiple stressors during the embryonic development of this species of squid, but do not predict how this species would fare under these future ocean scenarios.
海洋酸化（OA）和海洋变暖是沿海生态系统和物种面临的重大问题。大西洋长鳍乌贼是西北大西洋营养网的核心组成部分，在长期高浓度酸化环境（2200 ppm）下已表现出生长减缓、发育延迟等影响，但尚未对该物种进行海洋酸化和变暖的综合影响研究。在本研究中，将乌贼卵囊置于几种酸化水平（400、2200和3500 ppm）和温度（20和27°C）的组合条件下进行培育。在2016年繁殖季节（5月至10月）的三次试验中，对孵化出的幼体进行了一系列指标的测量[背甲长度（DML）、卵黄囊体积（YV）、畸形情况和孵化成功率]。尽管观察到该物种对压力源具有显著抗性，突显了不同卵囊内部和之间的变异性，但在最高海洋酸化暴露水平下，胚胎的背甲长度减小且出现畸形。令人惊讶的是，尽管反应存在差异，但温度升高似乎并未加剧海洋酸化的影响。孵化时间随酸化程度增加而延长，在变暖条件下缩短幅度更大，并且进一步减少或消除了酸化导致的延迟。孵化成功率虽因卵囊而异，但呈现出一致的模式，即在酸化条件下胚胎后期损失更大，在变暖条件下早期损失更大，突显了这些压力源对该系统影响时间的潜在差异，即随着胚胎生长和呼吸，酸化压力在卵囊内随时间积累并产生影响。与在环境温度下饲养的幼体相比，在较高温度条件下暴露于高海洋酸化水平的孵化幼体往往表现出较小的影响。这可能是由于胚胎在较高温度处理下发育速度加快，从而减少了暴露于海洋酸化的时间。这些结果表明，在这种乌贼胚胎发育过程中，对多种压力源具有显著的潜在可塑性，但无法预测该物种在未来海洋环境下的表现。
