Browsing by Author "Khan, S Ajmal"
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Item Role of probiotics on the environment of shrimp pond.(2003-01-17) Sambasivam, S; Chandran, R; Khan, S AjmalRecent disease outbreak in shrimp farming caused mainly by bacteria, virus, fungi or a combination of these etiologic agents is attributed to disturbance in the environment of pond. To combat this, different antibiotics and chemicals are being used which are reported to be not environment friendly. Of late, a new and unique biotechnological product called "Probiotics " is being used widely by all the shrimp farmers worldwide, which is found to be more effective and environmentally safe also. In the present study 2 probiotics were used in a small 0.7 ha shrimp farm near Pattukottai in Tamil Nadu State for one culture period for the management of pond environment and also the gut ecology of Penaeus monodon. The environmental parameters analysed were within the acceptable limits. It was evident from the results that the production was better in the experimental pond where the probiotics were used. The biological parameters such as the average body weight, FCR and total harvest achieved were better in the experimental pond than the control pond, all due to congenial environment, which obtained in the former mainly due to the use of probiotics.Item Toxicity of leaf extract of yellow oleander Thevetia nerifolia on Tilapia.(2003-04-17) Sambasivam, S; Karpagam, G; Chandran, R; Khan, S AjmalThe usefulness of leaf extract as an ideal source of 'piscicide' in shrimp farming is described Leaf toxins are safe, eco-friendly and biodegradable. The fish Tilapia, Oreochromis mossambicus was exposed to the extract and the percentage of mortality at the end of 24,48, 72 and 96 hrs was recorded. The respective toxic range of aqueous, alcohol and acetone extracts of 24 hr LC50 and 96 hr LC50 values were found to be respectively 1118.79-330.30, 699.24-129.02 and 749.95-347.23 mg dry extract/litre for Oreochromis mossambicus. The LC50 values observed in different time periods in the fish exposed to aqueous extract were relatively high compared to the values obtained in acetone and alcohol extracts. Use of leaf extract, as piscicide in aquaculture farms is considered advantageous when viewed against the backdrop of using persistent chemicals.Item Use of benthic biodiversity for assessing the impact of shrimp farming on environment.(2009-09) Murugesan, P; Ajithkumar, T T; Khan, S Ajmal; Balasubramanian, TAn attempt was made to find out the impact of shrimp farm discharges on benthic diversity in the discharge point of a shrimp farm. The duration of the study was one culture period right from stocking to harvest. The results revealed that the values of environmental entities were in the safe levels. As regards nutrients, maximum value of TOC and phosphorus were recorded in the sample collected after harvest and minimum in the sample collected during culture. BIO-ENV method revealed that nitrogen, sediment salinity and TOC were manifested as best variable combination explaining faunal distribution. Polychaetes are the dominant group (50%) with 13 species followed by crustaceans (32%) with 10 species, gastropods (10%) with 2 species and bivalves (8%) with 3 species. The faunal density was found to vary in relation to months as observed in the samples which were collected during various seasons in the other areas of estuary. In line with this, diversity values were also paralleled to the faunal density. In a nut shell, the study revealed no negative impact of shrimp farming to the estuarine benthic biota.