320
Plastic Basket Tray
Plastic baskets are also suitable for nursing and rearing oyster spats. Holes are
drilled in the upper corners for tying the suspension ropes. Best quality baskets are
chosen otherwise they cannot last for long period.
Note: Instead of rack and tray and rack and string culture, concrete cubical pillars can also be constructed which is again a suitable substratum for the setting of
oyster spats.
Oyster Culture Technology with Special Reference to Indian
Sundarbans
The Indian Sundarbans is a vibrating ecosystem from the point of view of physicochemical variables and significant spatial and temporal variations of water salinity, pH, nutrient level and turbidity exist in this dynamic geographical locale
(Mitra et al. 2004). The lower stretch of the estuarine complex and high saline
zones (e.g., Namkhana block, Sagar block, Patharpratima block etc.) are extremely
favourable for edible oyster culture. Saccostrea cucullata is the dominant oyster
species in Indian Sundarbans and mean population density is around 385/m
2
(Table 9.13).
In context to lower stretch of Indian Sundarbans, the relevant parameters, which
have major role in regulating the oyster populations, are surface water temperature,
salinity, turbidity (expressed as extinction coefficient), wave action, nutrient (nitrate,
phosphate and silicate) and phytoplankton population. A brief account of each of
these parameters is necessary to justify the commercial viability of oyster culture in
this mangrove dominated deltaic lobe at the apex of Bay of Bengal.
Surface Water Temperature
Surface water temperature has profound influence on biotic community (Mitra et al.
2004). It regulates the composition of phytoplankton community (the major food of
oysters) by increasing the dominancy of flagellates in warm stratified waters of
coastal regions (Strickland 1983; Maestrini and Graneli 1991). It has been observed
that low temperature and low dissolved oxygen often limit the germination of phytoplankton cyst (Ishikawa and Taniguchi 1994; Blanco 1995). In this context it is to
be mentioned that the environment of Indian Sundarbans is ideal for oyster culture
as temperature lower than 20 °C seldom reaches in this deltaic lobe, which is
extremely congenial for phytoplankton stock acceleration. The water temperature
also influences the process of gametogenesis and breeding cycle in marine and estuarine organisms. Most of the members of nekton and benthos in coastal West Bengal
breed during the onset of summer, when the temperature of the ambient water is in
a state of gradual increase.
9 Mangroves: A Source of Existing and Alternative Livelihood
Plastic Basket Tray
Plastic baskets are also suitable for nursing and rearing oyster spats. Holes are
drilled in the upper corners for tying the suspension ropes. Best quality baskets are
chosen otherwise they cannot last for long period.
Note: Instead of rack and tray and rack and string culture, concrete cubical pillars can also be constructed which is again a suitable substratum for the setting of
oyster spats.
Oyster Culture Technology with Special Reference to Indian
Sundarbans
The Indian Sundarbans is a vibrating ecosystem from the point of view of physicochemical variables and significant spatial and temporal variations of water salinity, pH, nutrient level and turbidity exist in this dynamic geographical locale
(Mitra et al. 2004). The lower stretch of the estuarine complex and high saline
zones (e.g., Namkhana block, Sagar block, Patharpratima block etc.) are extremely
favourable for edible oyster culture. Saccostrea cucullata is the dominant oyster
species in Indian Sundarbans and mean population density is around 385/m
2
(Table 9.13).
In context to lower stretch of Indian Sundarbans, the relevant parameters, which
have major role in regulating the oyster populations, are surface water temperature,
salinity, turbidity (expressed as extinction coefficient), wave action, nutrient (nitrate,
phosphate and silicate) and phytoplankton population. A brief account of each of
these parameters is necessary to justify the commercial viability of oyster culture in
this mangrove dominated deltaic lobe at the apex of Bay of Bengal.
Surface Water Temperature
Surface water temperature has profound influence on biotic community (Mitra et al.
2004). It regulates the composition of phytoplankton community (the major food of
oysters) by increasing the dominancy of flagellates in warm stratified waters of
coastal regions (Strickland 1983; Maestrini and Graneli 1991). It has been observed
that low temperature and low dissolved oxygen often limit the germination of phytoplankton cyst (Ishikawa and Taniguchi 1994; Blanco 1995). In this context it is to
be mentioned that the environment of Indian Sundarbans is ideal for oyster culture
as temperature lower than 20 °C seldom reaches in this deltaic lobe, which is
extremely congenial for phytoplankton stock acceleration. The water temperature
also influences the process of gametogenesis and breeding cycle in marine and estuarine organisms. Most of the members of nekton and benthos in coastal West Bengal
breed during the onset of summer, when the temperature of the ambient water is in
a state of gradual increase.
9 Mangroves: A Source of Existing and Alternative Livelihood