Mechanism for preventing fungal infection with Halocrusticida okinawaensis in larvae of swimming crab by adjusting pH of rearing water to 9.25
2006
Yasunobu, H.(Hyogo-ken. Fisheries Experiment Station, Akashi (Japan))
The mechanism for preventing fungal infection with Halocrusticida okinawaensis in larvae of swimming crab (Portunus trituberculatus) by adjusting pH of rearing water to 9.25 was investigated. The number of zoospores discharged in pH 9.25 sea water was not different from that in pH 8.00 sea water. Survival of zoospores at pH 9.25 sea water was about 1/3 of the survival at pH 8.00. Motility of zoospores was observed at 60 min after inoculation in pH 8.00 sea water, but at pH 9.25 motility was not observed after 30 min. The number of adhering zoospores on carapace of adult swimming crab in pH 9.25 sea water was not different from that in pH 8.00 sea water. These results with previous findings indicate that inhibition of the germination of encysted zoospores and reduction of the number of surviving zoospores in pH 9.25 sea water plays an important and secondary roles, respectively, in preventing fungal infection with H. okinawaensis in swimming crab larvae.
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