No abstract

No abstract

Quality of water in shrimp culture ponds depends on several physical, chemical and biological processes. In this study, the physico-chemical characteristics of water and sediment samples from inlet, pond and outlet of a traditional shrimp culture pond, locally called as bheri, were examined for nine months from March to November 2011. Majority of the physicochemical parameters of bheri were well within the optimum levels. The average BOD values in pond water and outlet water were 2.03 ppm and 2.33 ppm, respectively. In pond water, the levels of ammonia were from 0.012 to 0.033 ppm, which was well within the safe level (<0.1 ppm). The present study recorded low levels of nitrite (0.0037 to 0.0043 ppm) and nitrate (0.056 -0.091 ppm) in pond water, which was within the safe levels recommended for shrimp farming. These physicochemical parameters did not affect the cultured shrimp as there was no incidence of diseases or growth retardation during the culture period. The effluent water characteristics also did not vary much and well within the recommended levels for protecting the coastal ecosystem. It is unlikely that the traditional shrimp culture pose any adverse environmental effect when effluents are discharged into the open coastal ecosystem.

Quality of water in shrimp culture ponds depends on several physical, chemical and biological processes. In this study, the physico-chemical characteristics of water and sediment samples from inlet, pond and outlet of a traditional shrimp culture pond, locally called as bheri, were examined for nine months from March to November 2011. Majority of the physicochemical parameters of bheri were well within the optimum levels. The average BOD values in pond water and outlet water were 2.03 ppm and 2.33 ppm, respectively. In pond water, the levels of ammonia were from 0.012 to 0.033 ppm, which was well within the safe level (<0.1 ppm). The present study recorded low levels of nitrite (0.0037 to 0.0043 ppm) and nitrate (0.056 - 0.091 ppm) in pond water, which was within the safe levels recommended for shrimp farming. These physicochemical parameters did not affect the cultured shrimp as there was no incidence of diseases or growth retardation during the culture period. The effluent water characteristics also did not vary much and well within the recommended levels for protecting the coastal ecosystem. It is unlikely that the traditional shrimp culture pose any adverse environmental effect when effluents are discharged into the open coastal ecosystem.

Penaeus vannamei farming has been the major aquaculture practice in the Indian Sundarbans. This study investigated the physicochemical characteristics, management practices, distribution of vibrios, and the prevalence of bacterial, parasitic and viral diseases in 14 P. vannamei intensive culture farms in the Indian Sunderbans during 2016. The total heterotrophic counts of the pond water ranged from 3.53 to 6.21 log 10 cfu/ml. The presumptive vibrios were in the range of 2.40-4.99 log 10 cfu/ml. Mild vibriosis was noted in 3 farms. Twenty out of 21 isolates from the haemolymph samples were confirmed to be Vibrio parahaemolyticus by the PCR amplification of the toxR gene. No acute hepatopancreatic necrosis disease (AHPND) causing V. parahaemolyticus (Vp AHPND ) strain was, however, detected. Of the 14 shrimp farms surveyed, only one farm sample was white spot virus (WSV) positive and all others were negative. All the P. vannamei farms were negative for infectious hypodermal and haematopoietic necrosis virus, hepatopancreatic parvo-like virus, and infectious myonecrosis virus. No incidence of Enterocytozoon hepatopenaei, white faecal syndrome, running mortality syndrome, protozoan infestation, and luminous vibriosis was observed during the survey period. The survival rate was 90-95% in the normal ponds, while the lowest survival was 60% in an asymptomatic WSV infected farm. The physicochemical characteristics of the farms were well within the optimum, except for the WSV infected farm, which had high ammonia levels. Due to the lack of awareness on the P. vannamei farming practices and high operational costs, the biosecurity measures were not strictly followed in the surveyed farms.