Pathological investigations of Crassostrea madrasensis (Preston, 1916) in cultured and wild habitats from Southern India

Suja, G (2018) Pathological investigations of Crassostrea madrasensis (Preston, 1916) in cultured and wild habitats from Southern India. Doctoral thesis, ICAR- Central Marine Fisheries Research Institute.

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    Edible oyster populations of the Indian coast are currently naive and are not subjected to live introductions or trans-boundary movements. There were no previous reports on edible oyster mortality due to disease out breaks in the country. Still, the major reported parasites in oysters over the world have been observed in the present study within a low prevalence. The two OIE listed pathogens, Bonamia ostrea and Marteilia refringens, the protozoan, Perkinsus beihaiensis, the trematode, Bucephalus sp. and the shell parasite Polydora sp. are those that have the potential to be a problem for the future farming. Hence a comprehensive screening for pathogens in other beds throughout the coastline is strongly recommended. Presently oyster farming is getting popularized and is being extended to more and more regions along the coast. At this stage, a good baseline data on parasites and pathogens within natural environments is necessary for proper disease management. The baseline data generated in this study will be helpful for planning a health monitoring program in Crassostrea madrasensis The farming site at Sathar Island was found to have the advantage of producing oysters with high condition index and low incidence of parasites. The duration of farming limiting to one year was found to be ideal since it reduces the exposure period for parasite entry. But the presence of the major protozoan parasites in the ecosystem should be considered while expanding and intensifying oyster culture in future as the stressful condition can cause parasitic proliferation in the ecosystem. A similar situation was observed in mussel farming grounds along the west coast of India where a proliferation of OIE listed protozoan, Perkinsus olseni was associated with intensification of mussel culture. The nested primers developed for the major protozoan parasites in this study can be used for screening the stocks for selecting brood stock and for planning farming sites. As PCR screening using these primers is more sensitive than the conventional methods, movement of infected stocks to uninfected regions can be minimised based on this screening In conclusion, Crassostrea madrasensis stocks along the south Indian coast (with respect to the stations studied) were found to be safe with a low prevalence of pathogens. But, the comparatively higher burden of parasites and pathological conditions observed in Tuticorin Bay indicates the impact of contaminant exposure. Thus for maintaining the good health status of oyster stocks, periodic surveillance and monitoring are necessary and also the water quality should be regularly monitored for better control over the chances of disease out breaks especially around the cultured areas.

    Item Type: Thesis (Doctoral)
    Uncontrolled Keywords: Pathological investigation; Crassostrea madrasensis; bivalve aquaculture; Indian backwater oyster; disease surveillance and control
    Subjects: Molluscan Fisheries > Edible oyster
    Fish and Fisheries > Fish Pathology
    Fish Biotechnology
    Molluscan Fisheries
    Divisions: CMFRI-Kochi > Marine Biotechnology
    Subject Area > CMFRI > CMFRI-Kochi > Marine Biotechnology
    CMFRI-Kochi > Marine Biotechnology
    Subject Area > CMFRI-Kochi > Marine Biotechnology
    Depositing User: Arun Surendran
    Date Deposited: 01 Jun 2019 10:15
    Last Modified: 01 Jun 2019 10:15

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