Department of Life Science, University of Modena and Reggio Emilia, Modena, Italy.
NBFC, National Biodiversity Future Center, Palermo, Italy.
J Exp Zool A Ecol Integr Physiol. 2023 Jul;339(6):578-589. doi: 10.1002/jez.2701. Epub 2023 Apr 11.
Long-term environment acidifications due to decrease pH of the rainwaters affect both soils and water bodies. The organisms most likely to be affected by acid rain are the ones that possess vital organs made of calcium carbonate; among them are tardigrades, presenting aragonite piercing stylets in feeding apparatuses. A positive relationship between acidic rainfall and loss of tardigrades diversity has been already shown, but there is lack of knowledge of its lethal and sublethal effects. This study quantifies the effects of the acute exposure of three eutardigrade, Acutuncus antarcticus, Hypsibius exemplaris, and Macrobiotus cf. hufelandi, to synthetic acid rains and to organic and inorganic acids (hydrochloric, acetic, sulfuric, and nitric acids) naturally occurring in the environment. The cumulative proportion of dead animals in respect of exposition time was fitted to cumulative Weibull Distribution using a Bayesian framework. At the end of the experiments, animals were observed to investigate damages to their piercing stylets. Besides, stylets were finely morphologically described with Scanning Electron Microscopy. This study shows that acid rains and the other tested acids negatively affect tardigrades accordingly with pH, time of exposure, and tardigrade species. Freshwater species show a better resistance to acidity than the moss dwelling species, which can better acclimate over the time to low pH. The stylets resulted unaltered in almost all of the alive specimens. The results suggest that the tested tardigrades taxa have the ability to buffer the environmental proton change and the negative effect on their populations could be counteracted.
由于雨水 pH 值下降而导致的长期环境酸化会影响土壤和水体。最容易受到酸雨影响的生物是那些拥有碳酸钙重要器官的生物，其中包括缓步动物，它们在进食器官中具有霰石刺穿的口针。已经表明，酸性降雨与缓步动物多样性的丧失之间存在正相关关系，但对于其致死和亚致死效应的了解还很缺乏。本研究量化了三种喜湿缓步动物（南极阿塔卡马缓步动物、Hypsibius exemplaris 和 Macrobiotus cf. hufelandi）急性暴露于人工酸雨以及环境中天然存在的有机和无机酸（盐酸、乙酸、硫酸和硝酸）的影响。根据暴露时间，将死亡动物的累积比例拟合到累积 Weibull 分布中，采用贝叶斯框架。在实验结束时，观察动物以调查其刺穿口针的损伤情况。此外，使用扫描电子显微镜对口针进行了精细的形态描述。本研究表明，酸雨和其他测试的酸会根据 pH 值、暴露时间和缓步动物的种类对缓步动物产生负面影响。淡水物种比苔藓栖息物种对酸度具有更好的抵抗力，后者可以随着时间的推移更好地适应低 pH 值。几乎所有存活的标本中的口针都没有变化。结果表明，测试的缓步动物类群具有缓冲环境质子变化的能力，其对种群的负面影响可能会得到抵消。
