Crait Jamie R, McIntosh Antoinette D, Greiner Ellis C, Ben-David Merav
Department of Zoology and Physiology, Program in Ecology, University of Wyoming, Laramie, Wyoming 82071;
J Parasitol. 2015 Apr;101(2):240-3. doi: 10.1645/14-546.1. Epub 2014 Sep 5.
Parasite prevalence in predatory mammals is influenced by numerous factors including diet, sex, season, and habitat. We examined the effect of such factors on the prevalence of gastrointestinal helminths in North American river otters ( Lontra canadensis ) in Yellowstone Lake, Yellowstone National Park. Otters in this ecosystem have recently experienced a decline in their main prey, Yellowstone cutthroat trout ( Oncorhynchus clarkii bouvieri), and have, in turn, increased consumption of alternative foods. Helminths were found in 13.2% of otter fecal samples. The dominant parasite was a Diphyllobothrium sp. ( Diphyllobothrium ditremum or Diphyllobothrium dendriticum ), a cestode acquired from cutthroat trout. Truttaedacnitis truttae and Contracaecum spp. nematodes were incidental parasites in otter feces, and acanthocephalan eggs were found in 1 sample. The prevalence of trout remains and a Diphyllobothrium sp. in otter feces was higher during the cutthroat trout spawning season. A Diphyllobothrium sp. was more prevalent in the feces of female otters. There was no relationship between annual declines in the frequency of trout in otter feces and prevalence of parasites. Helminth prevalence and species richness in Yellowstone otters was low and likely reflects low predator densities and few intermediate hosts. This is the first study reporting the helminth fauna of river otters in the Greater Yellowstone Area and confirms the otter as a definitive host for Diphyllobothrium sp. in this region.
捕食性哺乳动物体内的寄生虫感染率受多种因素影响，包括饮食、性别、季节和栖息地。我们研究了这些因素对黄石国家公园黄石湖北美水獭（加拿大水獭）胃肠道蠕虫感染率的影响。在这个生态系统中，水獭的主要猎物黄石虹鳟（克拉克氏虹鳟）数量最近有所下降，因此它们转而增加了对替代食物的消耗。在13.2%的水獭粪便样本中发现了蠕虫。主要寄生虫是一种裂头绦虫属（可能是宽节裂头绦虫或树枝状裂头绦虫），这是一种从虹鳟身上感染的绦虫。鳟鲔吸虫和对盲囊线虫属线虫是水獭粪便中的偶然寄生虫，在1个样本中发现了棘头虫卵。在虹鳟产卵季节，水獭粪便中虹鳟残骸和裂头绦虫属的感染率更高。裂头绦虫属在雌性水獭粪便中更为普遍。水獭粪便中虹鳟出现频率的年度下降与寄生虫感染率之间没有关系。黄石水獭体内蠕虫的感染率和物种丰富度较低，这可能反映了捕食者密度低和中间宿主较少。这是第一项报道大黄石地区水獭蠕虫动物群的研究，并证实水獭是该地区裂头绦虫属的终末宿主。
