| Summary: | 碩士 === 國立臺灣海洋大學 === 水產養殖學系 === 94 === Abstract
Since 2001, the artificially reproduced Small abalone Spats Suffered from albinism, falling off and mass mortalities during 10 to 21 days post substratum settling. These phenomena seriously affected the spat production, its price and the survival of the small abalone aquaculture industry in Taiwan. This study investigated the etiology of withering adults, the control measures using disinfectants to reduce bacterial counts on the surfaces of Gracilaria spp. and fertilized eggs and the use of different nursery systems to improve spat settlement.
No virus particles and rickettsia-like bacteria were found in the withering adults of small abalone as examined by using histopathological technique, TEM observation and PCR reactions. However, the three commonly found pathogens Vibrio alginolyticus, V. carchariae and V. parahaemolyticus, were isolated from the withering adults with V. alginolyticus as the dominant species isolated.
For the improvement of spat settling, flow-filter tank, ozone exposure mixed with flow-filter tank, UV treatment and protein skimmer added systems were employed in this study. The results revealed that all the systems employed could improve spat setting rates except UV treatment.
Various disinfectants including ClO2, KMnO4, iodophor and ozone were used to reduce bacterial counts on the surfaces of Gracilaria spp. and fertilized eggs of small abalone. The results revealed that the treatment using concentration of KMnO4, ozone and iodophor higher than 2ppm could damage the Gracilaria spp. and fertilized eggs. The use of KMnO4 and ozone exposure exhibited best bacteriocidal effect while the ClO2 exposure exhibited apparent improvement of spat settling.
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