Environmental impact assessment of suspended oyster, Crassostrea madrasensis (Preston) culture

Ramalinga, , (2006) Environmental impact assessment of suspended oyster, Crassostrea madrasensis (Preston) culture. PhD thesis, Central Institute of Fisheries Education, Mumbai.

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Abstract

The environmental impact due to farming of the Indian backwater oyster Crassostrea madrasensis (Preston) for five consecutive years was studied. The changes during crop holiday periods of three; six and nine months were also assessed. The water column and sediment characteristics and benthic macrofaunal community changes of farm sites of different farming and crop holiday periods were compared with those of reference sites. The study indicated that there were no significant variations in the hydrographic parameters due to continuous farming. Howeve ~ the sediment characteristics and the benthic macrofaunal composition at the farm sites were found to change with continuous farming. The percentage of coarse and fine sand was found to decrease while that of silt, clay and organic carbon found to increase with the year of farming. The impact on sediment characteristics due to farming for two years could be rectified with a crop holiday of six months period but the impact due to continuous farming for five years could not be rectified even with a long-term crop holiday of nine months. The benthic macrofaunal communities of the farm and reference sites were found to vary with the year of farming. The number of species recorded at the farm and reference site of first year of farming was almost similar (30 for farm site, 28 for reference site). The number of species recorded for the second year farming period was 24 for farm site and 33 for reference site, but the difference was not significant. On the contrary, Significant differences were found in the number of species at the farm and reference sites of three, four and five years of farming. The number of individuals was always higher at the reference sites than that of farm sites. Maximum number of individuals (1278 m·2 ) was recorded at the first year farm site and the minimum (279 m·2) at the fourth year farm site. Improvements in number of species, number of individuals were noticed at farm sites when crop holiday was given and a crop holiday of six months proved to be useful in rectifying the impact of oyster farming of two years. Based on findings of the present study it is recommended that oyster farming can be done continuously for a maximum period of two years and if the culture needs to be carried for more than two years at the same site, a crop holiday of at least six months is to be given. Altemately, the location of farming has to be shifted to an adjacent site after 2 years.

Item Type:Thesis (PhD)
Supervisor(s):Kripa, V
Uncontrolled Keywords:Environmental impact assessment; oyster; Crassostrea madrasensis (Preston) culture; oyster culture
Subjects:Molluscan Fisheries > Edible oyster
Theses
Divisions:CMFRI-Cochin > Marine Capture > Molluscan Fisheries
ID Code:7608
Deposited By:Dr. V Mohan
Deposited On:17 Feb 2011 17:28
Last Modified:21 Jan 2014 12:19

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