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Determination of Effective Dose of Ultraviolet Irradiation to Influent Water for Prevention of <i>Kudoa yasunagai</i> Infection
摘要： We determined the minimum ultraviolet (UV) irradiation dose to influent water to prevent Kudoa yasunagai infection, using microscopy and qPCR. The infection prevalence in Seriola lalandi reared in untreated water reached 45% while that in fish reared in UV-treated water at 5 mJ/cm2 remained below 10%. Additionally, 5 mJ/cm2 UV irradiation significantly reduced spore formation in the brain. No infection was detected when the water was treated with UV at the doses 15 and 30 mJ/cm2. These results indicate that K. yasunagai actinospores are relatively vulnerable to UV irradiation and the minimum effective dose lies between 5 and 15 mJ/cm2.
关键词： quantitative PCR,ultraviolet irradiation,Seriola lalandi,prevention,Kudoa yasunagai,hatchery
更新于2025-09-23 15:21:21
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Experimental evidence on prevention of infection by the ectoparasitic protozoans <i>Ichthyobodo salmonis</i> and <i>Trichodina truttae</i> in juvenile chum salmon using ultraviolet disinfection of rearing water
摘要： In northern Japan, juvenile chum salmon Oncorhynchus keta (Walbaum) are released from hatcheries to enhance the fishery resource. Infections with ectoparasitic protozoans, particularly the flagellate Ichthyobodo salmonis and the ciliate Trichodina truttae, occasionally cause severe mortality among hatchery- reared juveniles. This study examined the susceptibility of the two parasites to wide- ranging UV irradiation (experiment 1) and then investigated whether UV disinfection of the rearing water using a commercial device was useful for preventing infections among juveniles in a small-scale rearing system over a 28- day period (experiment 2). In experiment 1, parasite mortality reached 100% with UV irradiation doses of ≥9.60 × 105 μW s/cm2 for I. salmonis and ≥8.40 × 105 μW s/cm2 for T. truttae. In experiment 2, disinfection of the rearing water at a UV irradiation dose of 2.2 × 106 μW s/cm2 succeeded in complete prevention of both parasites in the juvenile salmon. These results elucidate the minimum dose of UV irradiation for inactivation of I. salmonis and T. truttae, and demonstrate the usefulness of water disinfection using a commercial UV irradiation device to prevent infections by these parasites in hatchery- reared juvenile chum salmon.
关键词： fish disease,hatchery fish,ultraviolet disinfection,rearing water,Oncorhynchus keta
更新于2025-09-09 09:28:46