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|Title:||Responses of succinate dehydrogenase and non-specific alkaline phosphatases and mortality of tilapia to ambient <i style="">p</i>H stress in a sewage-fed aquaculture pond|
Jana, B B
|Abstract:||The fish, tilapia (<i style="">Oreochromis mossambicus</i>) of 50-60 g body weight was experimentally exposed to effluent gradients of highly alkaline <i style="">p</i>H in a sewage-fed aquaculture farm for examining the <i style="">p</i>H stress-induced responses of mortality and the stress marker enzyme succinate dehydrogenase and the non-specific alkaline phosphatases of fish prior to death at different hours of intoxication. A second trial was performed after two months when water quality changed along the sewage effluent gradient. An <i style="">in situ </i>experiment was also performed for better understanding of the responses of enzymatic activities attributable to different levels of <i style="">p</i>H conditions. Time required for 100% mortality of fish tended to increase from 30 min in <i style="">p</i>H 11.6 to 22 hr in <i style="">p</i>H 10.2. There was no mortality of fish when water quality improved significantly (with <i style="">p</i>H ranging between 9.6 to 8.0) after two months. The activities of succinate dehydrogenase and intracellular alkaline phosphatases assayed in gills and liver prior to death of fish tended to reduce with increase in survival hour, following a pattern of decay curve. On the other hand, percent of enzymatic inhibition of the exposed fish over the control increased as the survival hour increased following a pattern of exponential curve. It<b style=""> </b>appears<b style=""> </b>that the highest water <i style="">p</i>H of 11.6, maximum ratio for ammonium to ammonium hydroxide (1: 21) and reduced level of dissolved oxygen (2.62 mg/l) were perhaps responsible for the 100% mortality of fish within 30 min of their exposure and the enzymatic activities in the gills and liver assayed prior to death of fish tended to reduce as the acclimatization period of fish increased and <i style="">vice-versa.</i>|
|ISSN:||0975-1009 (Online); 0019-5189 (Print)|
|Appears in Collections:||IJEB Vol.45(07) [July 2007]|
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