Department of Aquatic Resources, Institute of Freshwater Research, Swedish University of Agricultural Sciences, Drottningholm, Sweden.
J Fish Dis. 2023 Oct;46(10):1029-1047. doi: 10.1111/jfd.13822. Epub 2023 Jun 17.
Parasites negatively affect biological processes within their hosts, which may alter for example health, growth, and reproductive ability. Non-native invasive parasites, in particular, may have large effects on the endemic hosts, given that the hosts lack evolved specific defences against such parasites. The swim bladder nematode Anguillicola crassus, an invasive parasite originating from Asia, is found in the European eel (Anguilla anguilla, L. 1758), since the 1980s. We investigated whether A. crassus affected several indicators related to health of the European eel (spleen- and liver size, body fat content and relative condition). Our results indicate that during the continental residency of the eels, infection by A. crassus had no major negative impacts on the investigated health indicators at the generally low infection intensities present in this study (median 2-3 visible parasites). Given that many of the adult eels were found to have swim bladder damage, concerns about their spawning migration through deeper oceanic environments can still be raised. To allow further investigations, we suggest that quantification of swim bladder damage should be implemented in eel-monitoring programs. Compared to other parasite pressure parameters, swim bladder damage provides additional information about past infections and future problems.
寄生虫会对宿主的生物过程产生负面影响，例如影响宿主的健康、生长和繁殖能力。特别是非本地入侵寄生虫，由于宿主缺乏针对这些寄生虫的特定进化防御机制，可能会对当地宿主产生重大影响。游泳鳔线虫（Anguillicola crassus）是一种源自亚洲的入侵寄生虫，自 20 世纪 80 年代以来就在欧洲鳗鱼（Anguilla anguilla，L. 1758）中被发现。我们研究了游泳鳔线虫是否会影响欧洲鳗鱼的几个与健康相关的指标（脾脏和肝脏大小、体脂含量和相对状况）。我们的研究结果表明，在鳗鱼的大陆居留期间，在本研究中普遍存在的低感染强度（中位数为 2-3 个可见寄生虫）下，游泳鳔线虫的感染对调查的健康指标没有重大负面影响。鉴于许多成年鳗鱼的鳔已受损，仍需要对其在深海环境中的繁殖洄游表示关注。为了进行进一步的研究，我们建议在鳗鱼监测计划中实施鳔损伤的量化。与其他寄生虫压力参数相比，鳔损伤提供了有关过去感染和未来问题的额外信息。
