Li Wen X, Song Rui, Wu Shan G, Zou Hong, Nie Pin, Wang Gui T
State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, Hubei Province, P. R. China.
J Parasitol. 2011 Apr;97(2):192-6. doi: 10.1645/GE-2621.1. Epub 2010 Oct 28.
To understand the seasonal migration of the anadromous Coilia nasus , we attempted to identify the parasites infecting C. nasus and determine their seasonal occurrence. From June 2007 to July 2008, a survey of 775 C. nasus individuals from the estuary of the Yangtze River and the coast of the East China Sea revealed more than 7,300 parasites associated with the gills and alimentary tracts of C. nasus . The following 6 helminth taxa were identified, i.e., the monogeneans Heteromazocraes lingmueni and Helciferus tenuis, the digenean Elytrophallus coiliae, the acanthocephalan Acanthosentis cheni , and larvae of the nematodes Anisakis simplex and Contracaecum sp., all of which are marine or brackish-water parasites. The absence of freshwater helminths suggested that the parasites acquired in freshwater may have been accidentally, and easily, lost by the time the fish had reached the estuary and coast. Contrary to seasonal occurrence of the parasites' life cycles, the lowest mean abundance and prevalence of H. lingmueni and A. cheni occurred in August, which suggested the immigration of C. nasus from freshwater to the Yangtze estuary, with lower parasite burdens. The highest mean abundance and prevalence of the nematodes A. simplex and Contracaecum sp. in May and June, and the lowest in August, indicated the arrival of the fish from the coast and the Yangtze River, to the estuary, respectively. These findings suggested that a majority of the fish prepared for spawning migration in the estuary in spring and early summer and returned to the estuary after spawning in the lower and middle reaches of the Yangtze River in late summer.
为了解溯河洄游的刀鲚的季节性洄游情况，我们试图鉴定感染刀鲚的寄生虫，并确定它们的季节性出现规律。2007年6月至2008年7月，对长江河口和东海沿岸的775尾刀鲚个体进行的调查发现，与刀鲚鳃部和消化道相关的寄生虫有7300余条。鉴定出以下6种蠕虫类群，即单殖吸虫灵武宁氏异锚盘虫和细弱棘盘虫、复殖吸虫刀鲚艾氏吸虫、棘头虫陈氏棘吻虫，以及线虫简单异尖线虫和对盲囊线虫的幼虫，它们均为海洋或咸淡水寄生虫。未发现淡水蠕虫表明，鱼类在淡水中感染的寄生虫可能在其到达河口和海岸时意外且轻易地消失了。与寄生虫生命周期的季节性出现情况相反，灵武宁氏异锚盘虫和陈氏棘吻虫的平均丰度和感染率在8月最低，这表明刀鲚从淡水向长江河口洄游，寄生虫负荷较低。线虫简单异尖线虫和对盲囊线虫的平均丰度和感染率在5月和6月最高，8月最低，分别表明鱼类从海岸和长江到达河口。这些发现表明，大多数刀鲚在春季和初夏在河口准备产卵洄游，并在夏末在长江中下游产卵后返回河口。
