Powell M D, Åtland Å, Dale T
Norwegian Institute for Water Research, Bergen, Norway.
Institute for Marine Research, Bergen, Norway.
J Fish Dis. 2018 May;41(5):751-759. doi: 10.1111/jfd.12771. Epub 2018 Jan 18.
Jellyfish-induced gill pathology relies upon occasional diagnostic observations yet the extent and impact of jellyfish blooms on aquaculture may be significant. Idiopathic gill lesions are often observed in apparently healthy fish. This study exposed Atlantic salmon (Salmo salar L.) smolts to macerated Cyanea capillata at 2.5 and 5 g/L for 2 hr under controlled laboratory conditions. Blood chemistry and gill histopathology were examined over a subsequent 4-week period. Fish showed an acute response to the presence of jellyfish, including characteristic external "whiplash" discoloration of the skin and acute increases in blood electrolytes and CO concentration; however, these were resolved within 4 days after exposure. Histopathologically, gills showed first an acute oedema with epithelial separation followed by focal haemorrhage and thrombus formation, and then progressive inflammatory epithelial hyperplasia that progressively resolved over the 4 weeks post-exposure. Results were consistent with the envenomation of gills with cytotoxic neurotoxins and haemolysins known to be produced by C. capillata. This study suggests that many focal hyperplastic lesions on gills, especially those involving focal thrombi, may be the result of jellyfish stings. Thus, the presence of jellyfish and their impact may be severe and understated in terms of marine fish aquaculture and fish welfare.
水母引起的鳃部病变依赖于偶尔的诊断观察，但水母大量繁殖对水产养殖的影响程度可能很大。特发性鳃部病变常在看似健康的鱼类中观察到。本研究在受控实验室条件下，将大西洋鲑（Salmo salar L.）幼鱼暴露于浓度为2.5克/升和5克/升的捣碎的僧帽水母中2小时。在随后的4周内检查血液化学和鳃部组织病理学。鱼对水母的存在表现出急性反应，包括皮肤出现特征性的外部“鞭状”变色以及血液电解质和二氧化碳浓度急剧升高；然而，这些在接触后4天内得到缓解。组织病理学上，鳃首先出现急性水肿并伴有上皮分离，随后出现局灶性出血和血栓形成，然后是进行性炎症性上皮增生，在接触后的4周内逐渐消退。结果与已知由僧帽水母产生的细胞毒性神经毒素和溶血素对鳃的毒害作用一致。这项研究表明，鳃上许多局灶性增生性病变，尤其是那些涉及局灶性血栓的病变，可能是水母蜇伤的结果。因此，就海水鱼类养殖和鱼类福利而言，水母的存在及其影响可能很严重且被低估。
