氨對白蝦之毒性影響研究

Toxic Effects of Ammonia on White Shrimp (Litopenaeus vannamei)

郭恩展(En-Chan Kuo)

指導教授 ： 陳弘成

國立臺灣大學/生命科學院/漁業科學研究所/碩士(2006年)

https://doi.org/10.6342/NTU.2006.01174

摘要

白蝦養殖大都採用高密度集約養殖法，由於密度高、投餌量大、排泄物也多，因此水質容易惡化，其重要的環境限制因子之一就是有毒含氮廢物。氨除了會惡化水質，也會影響生物成長、增加耗氧與排氨，甚至改變血淋巴蛋白質和游離胺基酸，嚴重則會造成養殖生物有高的死亡率。本試驗目的即在探討白蝦在不同氨濃度環境中的一些生理反應，以了解在高密度集約養殖中，氨對於白蝦生理功能之影響，進而求得白蝦不產生緊迫反應、生長良好及減少疾病爆發的最適環境。急性毒方面，在鹽度30‰時24-、48-、72-與96-小時LC50總氨濃度為：95.20、68.28、53.44與46.98 mg/L；鹽度15‰時分別為：131.31、82.68、62.64與53.49 mg/L。成長方面，在鹽度15‰下，總氨濃度5、2.5 mg/L的處理組，其成長率顯著減低。另外，總氨濃度20、10 mg/L的處理組，其耗氧排氨率顯著增加。病理組織方面，總氨濃度40、20 mg/L的處理組，其鰓絲呈現融合及萎縮，而肝胰臟則有空泡化的現象。滲透壓方面，總氨濃度20、10 mg/L的處理組，其血淋巴滲透壓顯著上升。由結果可知，過高的氨濃度對於白蝦確實會造成生理上的影響，因此在進行白蝦養殖時須特別注意池水中的氨濃度。根據本試驗結果，建立白蝦水質基準中氨的最高限量，總氨濃度低於2.5 mg/L (NH3低於0.09 mg/L)，以避免白蝦受到氨的緊迫作用。

關鍵字

白蝦 ； 氨 ； 毒性 ； 鹽度

並列摘要

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.

並列關鍵字

litopenaeus vannamei ； ammonia ； toxicity ； salinity

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