碩士 / 國立臺灣大學 / 漁業科學研究所 / 94 / Culture of white shrimp (Litopenaeus vannamei) has been recently intensified for substitute of tiger prawn farming. In the intensive culture system, ammonia is the most common toxicant coming from excretion of cultured animals and decomposition of organic detritus like unconsumed feed and feces. Accumulation of ammonia in pond water may deteriorate water quality, reduce growth, increase oxygen consumption and ammonia-N excretion, change in hemolymph protein and free amino acid levels, and even cause high mortality. The purpose of the present study is to evaluate ammonia toxicity to L. vannamei in different ammonia levels at two salinities, and then offers good pond management for white shrimp farming. Results showed the 24, 48, 72, 96h-LC50 values of total ammonia-N were 95.20, 68.28, 53.44, 46.98 mg/L at 30‰; 131.31, 82.68, 62.64, 53.49 mg/L at 15‰, respectively. Furthermore, it was found that growth rate of shrimps decreased as increase of ammonia concentration at 15‰, and the oxygen consumption and ammonia-N excretion of shrimps increased with increase of ammonia concentration at two salinities. It is shown that acute exposure to high concentration of ammonia resulted in tissue damage, such as thickening, dilated gill and vacuolated hepatopancrease. Finally, it is obtained that osmotic pressure of hemolymph increased as increase in ammonia concentration at two salinities. According to the present study, toxicity of ammonia markedly affected physiology of white shrimps, and even caused death. In the practical aquaculture, the water quality is an important factor for the health of cultured animals, especially the ammonia levels that it has to be monitored very often. In conclusion, for farming white shrimp, the biologically safe level was estimated to be below 2.5 mg/L for TAN and 0.09 mg/L for NH3 at two salinities.
| Identifer | oai:union.ndltd.org:TW/094NTU05451008 |
| Date | January 2006 |
| Creators | En-Chan Kuo, 郭恩展 |
| Contributors | 陳弘成 |
| Source Sets | National Digital Library of Theses and Dissertations in Taiwan |
| Language | zh-TW |
| Detected Language | English |
| Type | 學位論文 ; thesis |
| Format | 82 |
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