Purpose

Endoparasitic nematodes of six harbour porpoises Phocoena phocoena and four grey seals Halichoerus grypus, stranded at the eastern coast of the Baltic Sea in Germany in winter 2019, were analysed in order to identify nematode parasites and to compare with recent studies from the same area.

Methods

Endoparasitic nematodes were identified by using both morphological and molecular characters. The successfully obtained sequences of the rDNA marker regions ITS-1, 5.8S, ITS-2 from 29 anisakid and the rDNA marker region ITS-2 of 11 pseudalid nematodes were amplified.

Results

Analyses revealed the presence of three parasite species, the anisakid nematode Contracaecum osculatum from grey seals and the pseudalid nematodes Pseudalius inflexus and Stenurus minor from the harbour porpoises. Other anisakid nematodes regularly occurring in the Baltic Sea, e.g. Anisakis simplex or Pseudoterranova decipiens, were not found.

Conclusions

The prevalence of 100% and a severe parasite load in grey seals demonstrated a very high C. osculatum infection of Baltic Sea fish as their regular prey. Prevalence of 33% for parasites in harbour porpoises and minor infection rates, combined with a distinct lack of anisakid nematodes, are typical for the current situation of the porpoise parasite fauna in the Baltic Sea. Invasive parasite species as possible indicators for climate change could not be detected.

中文翻译：

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波罗的海哺乳动物中的线虫寄生虫，来自德国海岸的灰海豹 (Halichoerus grypus (Fabricius, 1791)) 和港湾鼠海豚 (Phocoena phocoena (L.))。

目的

分析了 2019 年冬季滞留在德国波罗的海东海岸的六只港湾鼠海豚Phocoena phocoena和四只灰海豹Halichoerus grypus 的内寄生线虫，以识别线虫寄生虫并与同一地区最近的研究进行比较。

方法

通过使用形态和分子特征来鉴定内寄生线虫。对成功获得的29条异尖线虫rDNA标记区ITS-1、5.8S、ITS-2和11条假线虫rDNA标记区ITS-2序列进行扩增。

结果

分析表明三个寄生虫种类存在时，anisakid线虫Contracaecum osculatum从灰色密封件和pseudalid线虫Pseudalius inflexus和Stenurus次要从港湾鼠海豚。没有发现其他在波罗的海经常出现的异尖线虫线虫，例如异尖线虫单纯线虫或Pseudoterranova decipiens。

结论

灰海豹 100% 的流行率和严重的寄生虫负载表明波罗的海鱼作为其常规猎物的C. osculatum感染率非常高。港湾鼠海豚中寄生虫的患病率为 33%，感染率较低，再加上明显缺乏异尖线虫线虫，这是波罗的海鼠海豚寄生动物群当前状况的典型特征。无法检测到作为气候变化可能指标的入侵寄生虫物种。