Red king crab larval survival and development are resilient to ocean acidification Journal of Experimental Marine Biology and Ecology

Ocean acidification, a decrease in oceanic pH resulting from the uptake of anthropogenic CO2, can be a significant stressor for marine organisms. In this study, we reared red king crab larvae from hatching to the first crab stage in four different pH treatments: current surface ambient, diel fluctuation to mimic larval migration between the surface and mixed layer under current ambient conditions, pH 7.8, and pH 7.5. Larvae were monitored throughout development and the average length of each stage was determined. At each of the zoeal stages, the glaucothoe stage, and the first crab stage, we measured survival, morphometry, dry mass, and carbon, nitrogen, calcium, and magnesium content. Red king crab larvae were highly resilient to ocean acidification. There were no differences among treatments in survival or in average stage length. Although there were clear ontogenetic trends in size, weight, and elemental composition, most of these did not vary with pH treatment. Zoeal morphology did not vary among treatments, although glaucothoe and C1 crabs were slightly smaller in pH 7.8 than in the ambient treatment. Ambient larvae also had a slightly higher mass than pH 7.8 larvae but not pH 7.5. Ambient larvae had higher magnesium contents than pH 7.8 and pH 7.5, but calcium levels were the same. Ambient larvae also had slightly lower carbon and nitrogen content than pH 7.8 and pH 7.5 larvae but only in the 4th zoeal stage. Overall this study suggests that red king crab larvae are well adapted to a wide range of pH conditions and appear resilient to ocean acidification levels projected for the next two centuries.

海洋酸化（Ocean Acidification）指因吸收人为源二氧化碳（anthropogenic CO₂）导致的海洋pH值降低，可对海洋生物造成显著胁迫压力。本研究将红王蟹（Red King Crab）幼体从孵化阶段饲养至第一幼蟹阶段，设置了四组不同pH处理条件：当前表层海水常规pH组、模拟当前常规环境下幼体在表层与混合层（mixed layer）间洄游的昼夜波动（diel fluctuation）pH组、pH 7.8组以及pH 7.5组。研究全程监测幼体发育过程，并测定了各发育阶段的平均时长。在各状幼体（zoeal）阶段、大眼幼体（glaucothoe）阶段及第一幼蟹阶段，我们分别测定了其存活率、形态测量参数、干重以及碳、氮、钙、镁元素的含量。结果显示，红王蟹幼体对海洋酸化具有较强耐受性：各处理组间的存活率与平均发育时长均无显著差异。尽管幼体的体型、体重及元素组成存在明显的个体发育趋势，但其中多数指标并未随pH处理条件发生变化。状幼体的形态在各组间无显著差异，但大眼幼体与第一幼蟹在pH 7.8组中的体型略小于常规pH组。常规pH组幼体的干重也略高于pH 7.8组，但与pH 7.5组无显著差异。常规pH组幼体的镁元素含量高于pH 7.8与pH 7.5组，但钙元素含量各组一致。此外，仅在第四期状幼体中，常规pH组幼体的碳、氮元素含量略低于pH 7.8与pH 7.5组。总体而言，本研究表明红王蟹幼体能够适应宽泛的pH范围，并对未来两个世纪预测的海洋酸化水平展现出良好的耐受性。