2021

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Browsing 2021 by Author "Antony, Ally C."

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    Efficacy of a Closed Water Depuration System with Charcoal filter on the Bacteriological quality of Villorita cyprinoides var. cochinensis (Hanley, 1866)
    (Society of Fisheries Technologists (India)Cochin, 2021) Antony, Ally C.; Silvester, Reshma; Aneesa, P. A; Francis, Bini; Abdulla, Mohamed Hatha
    Bivalves are good bio-indicators of the sanitary quality of the aquatic bodies in which they survive. The sanitary quality of the shellfish harvesting areas is assessed based on the faecal coliforms/E. coli levels of the harvesting water/shellfish tissue; on exceeding the regulatory limits depuration suggested. In the present study, the efficacy of a closed water depuration system attached with a charcoal filter to depurate Indian black clams (Villorita cyprinoides var. cochinensis (Hanley, 1866) was evaluated. The depuration system consisted of a closed water holding glass tank, with a wall-hung immersion water pump which re-circulated (18 l min-1) the seawater [salinity – 10 ppt, pH -7.3, ambient temperature (29-30°C)] through a coconut shell based activated carbon (charcoal) filter. Clams were sampled at time intervals of 0, 6, 12, 24, 72, and 96 h to assess the reduction of total coliforms (TC), faecal coliforms (FC) and faecal streptococci (FS). Initial TC, FC, FS and Salmonella loads were assessed using standard microbiological methods. Salmonella was not detected in any of the clam samples. Complete removal of both FC and FS whose initial loads were 4.6 x 104 MPN 100 g-1 and 1.1 × 105 MPN 100 g-1 respectively was observed within 48 h. Maximum rate of depuration of TC, FC as well as FS were observed during the initial first 6 h. However, TC could not be fully depurated even after 96 h of depuration. The differences in the depuration rates of TC, FC and FS were found to be statisticallysignificant (p<0.05). The FC load of the black clams selected for the study conformed only to the class C shellfish growing area of EU which could be reduced to acceptable regulatory limits of <230MPN 100 g-1 of depurated shellfish; which proved the system used is efficient. The system uses simple, cost-effective, easily available, natural, and renewable water treating agent such as coconut shellbased activated carbon and is suitable for household purposes. In India, black clams do not have much export value and is also not preferred to be eaten raw. Hence less stringent, cost-effective, and simple depuration measures as mentioned above may be sufficient enough to meet the required sanitary quality as it is consumed only after proper cooking.
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    Survival Kinetics of Vibrio Species in a Tropical Estuary along the Southwest coast of India - as a function of selected Environmental Factors
    (Society of Fisheries Technologists (India), 2021) Silvester, Reshma; Antony, Ally C.; Yousuf, Jesmi; Madhavan, Ajin; Sooria, P. M.; Kokkat, Aswin; Harikrishnan, M.; Hatha, Mohamed
    Vibrio species, autochthonous to aquatic environments worldwide, comprises of various species causing serious infections in humans and aquatic animals. Studying the survival ability of pathogenic Vibrio spp. in the aquatic environments is significant to identify the risk posed by them to aquatic animals as well as the recreational users of the system. However, in spite of their public health significance, the removal kinetics of this organism are not studied in detail from Cochin estuary, a highly productive estuarine system along the south-west coast of India. Here we aim to study the survival kinetics of pathogenic Vibrio spp. (V. parahaemolyticus, V. mimicus, V. proteolyticus, V. alginolyticus and V. vulnificus) in the estuary as a function of biological and physicochemical factors based on microcosm experiments. All the five Vibrio spp. showed prolonged and better survival in the estuarine sediment compared to water. This indicates that the sediments of Cochin estuary may act as permanent repository of this bacterium and is a matter of serious concern. Biological factors and chemical composition of estuarine water revealed to play a significant role in the removal of Vibrios from the estuarine environment. Exposure to sunlight also exhibited deleterious effect on the survival of these organisms. Thus, our overall findings reveal that the estuarine system has a self-purifying capacity to control the pathogens such as Vibrio. However, entry of high load of pathogens into the system through pollution and anthropogenic activities may disrupt this balance.