Global warming is having a significant impact around the world, modifying environmental conditions in many areas, including in zones that have been thermally stable for thousands of years, such as Antarctica. Stenothermal sedentary intertidal fish species may suffer due to warming, notably if this causes water freshening from increased freshwater inputs. Acute decreases in salinity, from 33 down to 5, were used to assess osmotic responses to environmental salinity fluctuations in Antarctic spiny plunderfish Harpagifer antarcticus, in particular to evaluate if H. antarcticus is able to cope with freshening and to describe osmoregulatory responses at different levels (haematological variables, muscle water content, gene expression, NKA activity). H. antarcticus were acclimated to a range of salinities (33 as control, 20, 15, 10 and 5) for 1 week. At 5, plasma osmolality and calcium concentration were both at their lowest, while plasma cortisol and percentage muscle water content were at their highest. At the same salinity, gill and intestine Na⁺-K⁺-ATPase (NKA) activities were at their lowest and highest, respectively. In kidney, NKA activity was highest at intermediate salinities (15 and 10). The salinity-dependent NKA mRNA expression patterns differed depending on the tissue. Marked changes were also observed in the expression of genes coding membrane proteins associated with ion and water transport, such as NKCC2, CFTR and AQP8, and in the expression of mRNA for the regulatory hormone prolactin (PRL) and its receptor (PRLr). Our results demonstrate that freshening causes osmotic imbalances in H. antarcticus, apparently due to reduced capacity of both transport and regulatory mechanisms of key organs to maintain homeostasis. This has implications for fish species that have evolved in stable environmental conditions in the Antarctic, now threatened by climate change.

中文翻译：

---

清新对南极多刺掠夺鱼 Harpagifer antarcticus 渗透反应的影响

全球变暖正在世界范围内产生重大影响，改变了许多地区的环境条件，包括在几千年来一直保持热稳定的地区，例如南极洲。由于变暖，慢热定居潮间带鱼类可能会受到影响，特别是如果这导致淡水输入增加导致水体变淡。盐度的急剧下降，从 33 降至 5，用于评估南极多刺掠夺鱼Harpagifer antarcticus对环境盐度波动的渗透反应，特别是评估H. antarcticus是否能够应对清新并描述不同水平的渗透调节反应（血液学变量、肌肉含水量、基因表达、NKA 活性）。南极人适应了一系列盐度（33 作为对照，20、15、10 和 5）持续 1 周。5 岁时，血浆渗透压和钙浓度均处于最低水平，而血浆皮质醇和肌肉水含量百分比最高。在相同盐度下，鳃和肠 Na ⁺ -K ⁺-ATPase (NKA) 活性分别处于最低和最高。在肾脏中，NKA 活性在中等盐度（15 和 10）时最高。盐度依赖性 NKA mRNA 表达模式因组织而异。在编码与离子和水运输相关的膜蛋白（如 NKCC2、CFTR 和 AQP8）的基因表达以及调节激素催乳素（PRL）及其受体（PRLr）的 mRNA 表达中也观察到显着变化。我们的结果表明，清新会导致南极嗜血杆菌的渗透失衡，显然是由于关键器官的运输和调节机制维持体内平衡的能力降低。这对在南极稳定环境条件下进化的鱼类具有影响，现在受到气候变化的威胁。