碩士 / 國立屏東科技大學 / 獸醫學系 / 93 / The purpose of this study is to evaluate and causative relationship of the death of small abalones ( Haliotis divericolor supertexta ) based on the results of etiology and pathology. The fields studied are mainly in eastern part and some other counties of Taiwan.
Dead abalone samples collected from Eastern Marine Biology Research Ceanter of Fisheries Research Institute and abalone raising farms were used for pathogenic culture and identification. The results showed that the most important disease was Vibrio spp. infection and the main epidemic period was from April to June. Additionally, pathologic lesions caused by rickettsiales-like and parasitic infection were found. Most of abalone revealed bacterial infection, especially the high occurence in the hepatopancreas and foot. All of the bacteria being cultured were further tested by API 20 NE kits.
Seventeen cases from 9 farms were further identified. Among them, Vibrio parahaemolyticus ( 35.3％, 6/17 ) showed highest infectious rate, followed with V. alginolyticus ( 17.6％, 3/17 ), V. fluvialis ( 17.6％, 3/17 ), V. valnificus ( 11.8％, 2/17 ) and Vibrio spp. ( 5.9％, 1/17 ), non-vibrio pathogens, such as one Pasteurella pneumotropica and one Flavobacterium odoratum were also found. Infected abalone showed clinical signs of lower activity, poor appetide, mucualr cysts and whitecloudy on foot and the mantle was also atrophied and abscessated.
Histopathological examination revealed parasitic, bacterial, fungal and rickettsia-like infection. Thirteen out of 36 samples collected from 9 farms showed parasitic infection, as 9 were infected by gill balantium spp, and the other 4 were individually infected by systemic trematode, cryptosporidia, ambiphrya in the intestine and nenatodaes wrer found in the oral cavity. Systemic trematode infection showed whitish pearl-like and nodular foci on food and hepatopancreas. The lesion was similar to small whitish shrimp-like foci under light microscopcial examination. Bacterial clumps appeaed in intestine, muscle, ovary and hepatopancreas were found in 7 samples. There were 32 samples revealed Rickettsia-like organisms infection, as lesion most present in the intestine. In addition, basophilic inclusion bodies were found in the hepatopancreas, subbranchial gland, gill filament, vascular endothelia, and external renal capsules, but without typical pathological changes. Typical basophilic inclusions were found in two samples with necrotic mantle and hepatopancreas.
The results showed that the Vibrio spp. infection is the main cause of dead small abalone. The common infection of V. parahaemolyticus is also the cause of abalone withering syndrome, and the epidemic period is from April to June. When the sea water becomes too high or too low, the abalone will face more stress and are susceptible to Vibrio spp. infection which could induce high motality of abalone. Due to mild pathological lesion, the dead causes of small balone resulted of rickettsia-like, parasitic and fungal infection remains to be futher studied.
| Identifer | oai:union.ndltd.org:TW/093NPUST541023 |
| Date | January 2005 |
| Creators | Chin-Ting Chen, 陳進丁 |
| Contributors | Rey-Shyong Chen, 陳瑞雄 |
| Source Sets | National Digital Library of Theses and Dissertations in Taiwan |
| Language | zh-TW |
| Detected Language | English |
| Type | 學位論文 ; thesis |
| Format | 67 |
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