Ocean acidification is the decline in seawater pH that results from the absorption of atmospheric carbon dioxide (CO₂). Decreased pH has negative effects on survivability, growth, and development in many marine calcifiers, potentially resulting in reduced coral species richness. This reduction in richness could open new niche space, allowing the spread of invasive species, such as the upside‐down jellyfish (Cassiopea spp.). Like corals, this jellyfish forms symbiotic relationships with zooxanthellae, photosynthetic dinoflagellates. This study focused on the effect of seawater acidification in Cassiopea spp. We monitored zooxanthellae density and two measures of health (bell diameter and volume) in individuals of Cassiopea sp. at three pH levels chosen to mimic different open‐ocean average conditions: 8.2, representing pre‐industrial revolution conditions; and 7.9 and 7.6, representing predicted declines in pH in the next century. Zooxanthellae density and health of the jellyfish were measured twice—prior to experimental manipulations and after four weeks of exposure to experimental pHs—in three consecutive trials. The effects of pH and Trial on proportional change in jellyfish attributes were analyzed using generalized linear mixed models. We found no significant effects of either factor. These results indicate that decreasing seawater pH has no apparent negative effect on zooxanthellae density or health in Cassiopea, which suggests that these jellyfish may be relatively insensitive to the impacts of ocean acidification, heightening its potential as an invasive species.

中文翻译：

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海水酸化会影响颠倒的水母Cassiopea spp中的黄原虫密度和健康吗？

海洋酸化是由于大气中二氧化碳（CO ₂）的吸收导致海水pH值下降。pH值降低会对许多海洋钙化剂的生存能力，生长和发育产生负面影响，可能导致珊瑚物种丰富度降低。丰富度的下降可能会打开新的利基空间，从而使诸如颠倒的水母（Cassiopea spp。）等入侵物种得以传播。像珊瑚一样，这种水母与虫黄藻（光合作用鞭毛虫）形成共生关系。这项研究的重点是Cassiopea spp中海水酸化的影响。我们监测了仙后座的虫黄藻密度和两项健康指标（钟形直径和体积）sp。在三个pH值水平下模拟不同的海洋平均条件：8.2，代表工业革命之前的条件；7.9和7.6，代表了预测的下一世纪pH值下降。在三个连续的试验中，在实验操作之前和暴露于实验pH值四个星期后，两次测量了水母的黄原虫的密度和健康状况。使用广义线性混合模型分析了pH和试验对水母属性比例变化的影响。我们发现这两个因素均无明显影响。这些结果表明，降低海水pH值对仙后座的虫黄藻的密度或健康没有明显的负面影响。，这表明这些水母对海洋酸化的影响可能相对不敏感，从而增强了其作为入侵物种的潜力。