Rückert Sonja, Klimpel Sven, Palm Harry Wilhelm
Heinrich-Heine-University Düsseldorf, Institute of Zoomorphology, Cell Biology and Parasitology, Universit&tsstr. 1, 40225 Düsseldorf, Germany.
Dis Aquat Organ. 2007 Mar 13;74(3):225-33. doi: 10.3354/dao074225.
Fifty specimens each of bream Abramis brama and roach Rutilus rutilus were examined for metazoan parasite fauna and trichodinid ciliates; 25 specimens of each species were collected from the Kiel Canal, a man-made waterway, and a nearby freshwater lake, the Dieksee. This is the first detailed parasitological examination of A. brama and R. rutilus at these locations: 30 parasite species were found, comprising 4 protozoans, 4 myxozoans, 5 digeneans, 3 monogeneans, 2 cestodes, 6 nematodes, 2 acanthocephalans, 3 crustaceans and 1 hirudinean. The crustacean Caligus lacustris occurred in both habitats while 2 other crustacean species, 2 acanthocephalans and 1 hirudinean were recorded exclusively for the lake habitat. Larval as well as adult stages of the different parasite species were found, indicating that both fish species act as intermediate and final hosts in both habitats. The Kiel Canal (total of 17 parasite species) showed a lower parasite species richness for A. brama and R. rutilus (14 and 10 parasite species, respectively) than the lake (25 parasite species). A. brama had a higher parasite richness (22 species) than R. rutilus (16 species) in the lake habitat. Most parasites collected were of freshwater origin. Consequently, the observed infection pattern of both fish species in the waterway is mainly influenced by the limited salinity tolerance of freshwater parasites, which are negatively affected even by a salinity of 2.3 to 4.5. In the central Kiel Canal, neither fish species was infected with marine parasites of low host specifity. These parasites are either limited by the low salinity at this sampling site (<4.5 to 6.0) or they cannot enter the canal due to the environmental conditions prevailing in this artificial brackish water habitat. Thus, the canal may comprise a natural barrier preventing the distribution of North Sea parasites into the Baltic Sea. However, the brackish water Baltic Sea nematodes Paracuaria adunca and Cosmocephalus obvelatus were found in R. rutilus from the canal, demonstrating the ability of some parasite species to invade and extend their range of distribution through this man-made shipping route from the Baltic to the North Sea.
对50条鲷鱼（Abramis brama）和50条拟鲤（Rutilus rutilus）样本进行了后生动物寄生虫区系和车轮虫纲纤毛虫检查；每种鱼的25个样本分别采集自基尔运河（一条人工水道）和附近的淡水湖迪克斯湖（Dieksee）。这是对这些地点的鲷鱼和拟鲤首次进行详细的寄生虫学检查：共发现30种寄生虫，包括4种原生动物、4种粘孢子虫、5种复殖吸虫、3种单殖吸虫、2种绦虫、6种线虫、2种棘头虫、3种甲壳动物和1种水蛭。甲壳动物湖鲺（Caligus lacustris）在两个栖息地均有出现，而另外2种甲壳动物、2种棘头虫和1种水蛭仅在湖泊栖息地被记录到。发现了不同寄生虫物种的幼虫和成虫阶段，这表明这两种鱼类在两个栖息地既是中间宿主也是终末宿主。基尔运河（共有17种寄生虫）中鲷鱼和拟鲤的寄生虫物种丰富度较低（分别为14种和10种寄生虫），低于湖泊（25种寄生虫）中的丰富度。在湖泊栖息地，鲷鱼的寄生虫丰富度（22种）高于拟鲤（16种）。采集到的大多数寄生虫起源于淡水。因此，观察到的这两种鱼类在水道中的感染模式主要受淡水寄生虫对盐度耐受性有限的影响，即使盐度为2.3至4.5也会对其产生负面影响。在基尔运河中部，两种鱼类均未感染宿主特异性低的海洋寄生虫。这些寄生虫要么受到该采样点低盐度（<4.5至6.0）的限制，要么由于这种人工半咸水栖息地的环境条件而无法进入运河。因此，这条运河可能构成了一道天然屏障，阻止北海寄生虫向波罗的海扩散。然而，在运河采集的拟鲤中发现了波罗的海半咸水线虫Paracuaria adunca和Cosmocephalus obvelatus，这表明一些寄生虫物种有能力通过这条从波罗的海到北海的人工航运路线入侵并扩大其分布范围。
