额尔齐斯河三代虫种类研究及新纪录种记述

Gyrodactylus Infection in Fish of the Ergis River and Report on New Record Species of Gyrodactylus

为探究额尔齐斯河水域中鱼类寄生三代虫的种类以及感染情况,给新疆水产业的发展及我国三代虫的研究提供基础资料,2009年8月至2014年8月选取额尔齐斯河的北屯镇、185团场、布尔津和哈巴河4个采样点,自捕或者从当地渔民处购买材料鱼,通过染色观察三代虫的形态特征,对其几丁质结构进行绘图、测量及比较,同时对不同种类三代虫的感染率、感染强度、感染丰度以及宿主专一性进行分析。结果表明,4个采样点共发现三代虫14种,其中丁鱥三代虫（Gyrodactylus tinca Malmberg,1957）、白斑狗鱼三代虫（Gyrodoctylus lucii Kulakowskaja,1951）、梭鲈三代虫（Gyrodoctylu luciopercae Gusev,1962）、马氏三代虫（Gyrodactylus markakulensis Gvosdev,1950）均是国内首次发现,为新纪录种;感染率最高的为鲤（Cyprinus carpio）（23.94%）,最低的为河鲈（Perca fluviatilis）（0.74%）,除东方欧鳊（Abramis brama orientalis）、散鳞镜鲤（Cyprinus carpio haematopterrus）和鲤外,其余的感染率均不超过10%;银鲫（Carassius auratus gibelio）、散鳞镜鲤和鲤为易感宿主,方均比（S2/X）都大于1,呈聚集分布;其余的小于1,呈均匀分布。三代虫宿主专一性较强,但有少数种类三代虫寄生2～4种宿主的情况,也存在同一宿主感染2～3种三代虫的现象,与单殖吸虫的宿主专一性基本一致。

Gyrodactylus,a monogenean Platyhelminthe,parasitize the skin and gills of host fish. The parasite reproduces rapidly,causing damage to the skin and gills that can lead to severe secondary infections. The problem has received the attention of scientists,both home and abroad. The Ergis River（ Chinese Section） is the only international river of the Arctic Ocean system in China. It originates in the Altai Mountains of Xinjiang and supports many European cold water fish,including Esox lucius,Lota lota,Tinca tinca,Perca fluviatilis and Leuciscus idus.The river has become important resource repository of European freshwater fish and the backbone of aquaculture in Xinjiang since connected with Wulungu Lake in 1986. With the development of aquaculture,the parasite has negatively affected fish breeding in the Ergis River and large scale farming of native fish,but relevant research on Gyrodactylus in Ergis River fish is lacking. This study seeks to further characterize the species,describe Gyrodactylus infection of fish in the Ergis River and provide basic data for fishery development in Xinjiang. The investigation was conducted at four sampling sites on the Ergis River from August,2009 to August 2014. Fish were captured by our team and purchased from fishermen. Gyrodactylus specimens from each host were sampled using a needle mounted under an anatomical lens. The mucus on the skin and gills was also examined under a microscope to detect the parasites. We observed the morphological characteristics of Gyrodactylus with a staining method,and made comparison of all Gyrodactylus species found during the investigation by drawing and measuring the chitin structures. We also analyzed and discussed the infection rates,infection intensity,infection abundance,and host specificity of different Gyrodactylus species on fish hosts. A total of 14 Gyrodactylus species were identified. Four species,G. tinca（ Malmberg,1957）,G. lucii（ Kulakowskaja,1951）,G. luciopercae（ Gusev,1962）,and G. markakulensis（ Gvosdev,1950） were observed for the first time in China. The fish species with the highest prevalence of Gyrodactylus was Cyprinus carpio（ 23. 94%）,and the lowest prevalence occurred in Perca fluviatilis（ 0. 74%）. Except for Abramis brama orientalis Berg,Cyprinus carpio haematopterrus and Cyprinus carpio,the species infection rates were less than 10%. Using an aggregated Gyrodactylus infection distribution,the most susceptible hosts were Carassius auratus gibelio,Cyprinus carpio haematopterus and Cyprinus carpio,all with mean squared values（ S^2/ X） 〉1.Mean squared values of infection rates for other fish species were all 〈1 and Gyrodactylus infection in these species displayed a uniform distribution. Our study shows that Gyrodactylus exhibits high host specificity,but a few Gyrodactylus species could infect two to four host species and several Gyrodactylus species may infect the same host,all consistent with the host specificity of Monogenea.