EFFECTS OF REARING CONDITIONS ON GROWTH AND MORTALITY OF JUVENILE CHUM SALMON (ONCORHYNCHUS-KETA) INFECTED WITH ICHTHYOBODO NECATOR
EFFECTS OF REARING CONDITIONS ON GROWTH AND MORTALITY OF JUVENILE CHUM SALMON (ONCORHYNCHUS-KETA) INFECTED WITH ICHTHYOBODO NECATOR
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DOI：
10.1139/f95-504
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发表时间：
1995-01-01
影响因子：
2.4
通讯作者：
URAWA, S
中科院分区：
文献类型：
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作者：
URAWA, S
鲑鱼 (Oncorhynchus keta) 幼鱼通过实验感染了博多科鞭毛虫 Ichthyobodo necator (Henneguy, 1883)，在 18 升水箱中以三种密度（300、600 和 1200 条鱼）饲养 5 周。调整水流入速率以给出拥挤和流速的五种组合。鱼体表寄生虫密度增加至2700-4100个寄生虫。 mm(-2) 在整个实验过程中并且在各组之间没有显着差异。在最不利条件（拥挤或供水不足）的感染群体中，总死亡率为 76-90%，而在其他感染群体中，总死亡率为 11-15%。前一组也表现出明显的生长减少。在未感染的对照中，死亡率较低（0.7-2.6%），并且拥挤程度或供水对生长或死亡率没有显着影响。受感染的鲑鱼对海水挑战的抵抗力也大大降低。所有在高放养密度或低流入率下饲养的鱼类都死于海水中。这些结果表明，当感染与过度拥挤和（或）供水不足引起的环境压力相结合时，鱼博多感染对宿主的生长和生存产生显着影响，尽管寄生虫密度不受这些因素的影响。
Chum salmon (Oncorhynchus keta) juveniles, experimentally infected with the bodonid flagellate Ichthyobodo necator (Henneguy, 1883), were reared in 18-L tanks at three densities (300, 600, and 1200 fish) for 5 weeks. Water inflow rates were adjusted to give five combinations of crowding and flow rate. The parasite density on the fish body surface increased to 2700-4100 parasites . mm(-2) over the course of the experiment and did not differ significantly among the groups. Total mortality was 76-90% in infected groups kept under the most unfavorable conditions (crowding or low water supply) but 11-15% in the other infected groups. The former groups also showed apparent growth reductions. In the uninfected controls, mortality was low (0.7-2.6%) and the degree of crowding or water supply had no significant effect on growth or mortality. Infected salmon were also much less resistant to seawater challenge; all fish kept at high stocking density or low inflow rate died in seawater. These results indicate that Ichthyobodo infections have marked effects on both host growth and survival when infections are combined with environmental stress induced by overcrowding and (or) inadequate water supply, although the parasite density is not affected by these factors.