Romberg Tiburon Center, San Francisco State University, 3150 Paradise Drive, Tiburon, CA 94920, USA.
J Exp Biol. 2013 Apr 15;216(Pt 8):1405-11. doi: 10.1242/jeb.078154.
Intertidal zone organisms naturally experience daily fluctuations in pH, presently reaching values beyond what is predicted for open ocean surface waters from ocean acidification (OA) by the year 2100, and thus present an opportunity to study the pH sensitivity of organisms that are presumably adapted to an acidified environment. The intertidal zone porcelain crab, Petrolisthes cinctipes, was used to study physiological responses to low pH in embryonic, larval and newly recruited juvenile life-history stages. In these crabs, embryonic development occurs in the pH-variable intertidal zone (pH 6.9-9.5), larvae mature in the more stable pelagic environment (pH 7.9-8.2), and juvenile crabs settle back into the pH-variable intertidal zone. We examined survival, cardiac performance, energetics and morphology in embryonic, larval and juvenile crabs exposed to two pH conditions (pH 7.9 and 7.6). Embryos and larvae were split by brood between the pH treatments for 9 days to examine brood-specific responses to low pH. Hatching success did not differ between pH conditions, but ranged from 30% to 95% among broods. Larval survival was not affected by acidification, but juvenile survival was reduced by ~30% after longer (40 days) exposure to low pH. Embryonic and larval heart rates were 37% and 20% lower at low pH, and there was a brood-specific response in embryos. Embryos did not increase in volume under acidified conditions, compared with a 15% increase in ambient conditions. We conclude that sustained exposure to low pH could be detrimental to P. cinctipes embryos and larvae despite the fact that embryos are regularly exposed to naturally fluctuating hypercapnic water in the intertidal zone. Importantly, our results indicate that early life-history stage responses to OA may be brood specific through as yet undetermined mechanisms.
潮间带生物自然会经历每日 pH 值的波动，目前已经达到了预计到 2100 年海洋酸化（OA）将使开阔海域表面海水 pH 值下降的程度，因此为研究那些可能适应酸化环境的生物对 pH 值的敏感性提供了机会。潮间带瓷蟹（Petrolisthes cinctipes）被用于研究胚胎、幼体和新招募的幼体生命史阶段对低 pH 值的生理反应。在这些螃蟹中，胚胎发育发生在 pH 值变化的潮间带（pH 6.9-9.5），幼体在更稳定的浮游环境中成熟（pH 7.9-8.2），幼蟹回到 pH 值变化的潮间带定居。我们研究了在两种 pH 条件（pH 7.9 和 7.6）下暴露的胚胎、幼体和幼蟹的存活率、心脏功能、能量学和形态。胚胎和幼虫在 pH 处理之间通过卵群分开 9 天，以研究低 pH 值对特定卵群的反应。孵化成功率在 pH 条件之间没有差异，但在不同卵群中从 30%到 95%不等。酸化对幼体存活率没有影响，但在较长时间（40 天）暴露于低 pH 值后，幼体存活率降低了约 30%。低 pH 值时，胚胎和幼体的心率分别降低了 37%和 20%，并且胚胎存在特定卵群的反应。与在环境条件下增加 15%相比，酸化条件下胚胎的体积没有增加。我们得出结论，尽管胚胎经常暴露在潮间带自然波动的高碳酸水中，但持续暴露于低 pH 值可能对 P. cinctipes 胚胎和幼体有害。重要的是，我们的结果表明，对 OA 的早期生命史阶段的反应可能通过尚未确定的机制而具有特定卵群的特征。
