Ahmad, 1990 stated that the coastal water of Bangladesh is one of the most productive areas in the world and is rich in fish and shellfish including molluscs. 3 | Channel characteristics, distribution and extent of oyster stocks, and seasonal changes in oyster meat were examined and the results are presented here. Observations on the relationship between length and weight of an organism are important in predicting the total production of said organism in terms of weight (Durve & Shrikhande, 1976).
The chemical composition of oysters cultured in Cork Harbor was similar to literature values for the same species cultured in Pacific waters. Therefore, the collector must go to the bottom of the water body to collect the samples. One opening of the oxygen tube is in the diver's mouth and the other opening is attached to the cylinder.
The fitness factor is considered one of the important factors affecting the body composition of molluscs. The condition index (CI) is generally defined as a measure of meat content relative to the overall size of the organism. Grave (1912) was the first to express oyster meat quality with such an index by using the volume of the meat divided by the volume of the shell cavity.
Samples were aspirated into the flame and the corresponding absorption of the characteristic radiation from each element was recorded.
Pictorial View of ProximateAnalysis
The estimation of the crude fat content was made by continuous extraction of fat with petroleum ether according to the AOAC method (2000). Aliquots of the chloroform layer extract were evaporated to dryness under nitrogen and the lipids were quantified gravimetrically. Fatty acid methyl esters (FAMEs) were obtained by the method described by Metcalfe et al.
The lipid extract fraction was saponified with 0.5 N NaOH in methanol, followed by methylation in 14% boron trifluoride in methanol (BF3/MeOH). The resulting methyl esters were analyzed using an Agilent 6890 N gas chromatography system equipped with a flame ionization detector (FID), a splitless injector, and a polar fused silica capillary column (30 m * 0.25 mm i.d. * 0.25 μm film thickness ). Heavy metals (Mercury 'Hg', Lead 'Pb', Cadmium 'Cd', Chromium 'Cr') will be analyzed from oven dried sample which will be sent to BCSIR (Bangladesh Council of Scientific and Industrial Research) seasonally where the analysis will be carried out using standard methods.
1981) using a Shimadzu LC-10AT high performance liquid chromatography (HPLC) chromatograph equipped with an ion exchange column, a quaternary pump, a 20 ll injection valve, and a fluorescence detector. Mobile phase A contained sodium citrate and ethanol (pH 3.5), and B contained sodium citrate and NaOH (pH 9.8). The flow rate was kept constant at 0.4 mL/min and the column temperature was set at 60 °C.
17 | P a g e derivatization by O-phthalaldehyde, amino acids were identified and quantified by comparing their retention times with those of standards (Sigma).
CHAPTER FOUR RESULT
The ash content observed highest in July, August and September and lowest in other months. The average heavy metal content was found to be 0.2330 ppm (dry meat weight basis) with a maximum of 0.36275 ppm observed in the rainy season and a minimum of 0.152 ppm observed in winter (Figure 12). The concentration of the selected heavy metals shows the seasonal trend as: Rainy season > Winter season > Spring > Autumn > Summer > Late autumn regardless of all heavy metals.
The Pb concentration in oyster muscle ranged from 0.56 ppm dry weight. during spring), while the Cr concentration reached 0.621 ppm dry weight. On the other hand, the Cd concentration was found to be 0.17 ppm dry weight. during winter), while the Hg concentration was constant around 0.1 ppm throughout the year (Figure 13). During this study, the content of different fatty acids was observed, ranging from myristic acid (14:0) to docosahexaenoic acid (22:6).
The findings showed that the fatty acid profile remained relatively constant during the study period with high concentrations of omega-3 fatty acids and 22:6). Palmitic acid (16:0) and oleic acid (18:1) were the main saturated and monounsaturated fatty acids, respectively. Among the essential amino acids, the highest content was lysine (5.23 g%), followed by aspartic acid (3.79 g%), the limiting amino acid leucine (2.99 g%); and threonine (2.69 g%) were also present in high concentration among non-essential amino acids (Figure 15). Details of the amino acid profile of C.
The protein content of oysters fluctuated during the study period, from the highest dry meat mass) in the rainy and autumn periods to the lowest in the spring period (Figure 16). Seasonal protein content of oyster meat was significantly different p<0.05 at 95% significance level (Appendix H). Lipid content differed significantly from season to season (p<0.05) at the 95% significance level (Appendix H).
The ash content varied significantly throughout the study period with the highest value during spring dry meat weight basis) and the lowest value in late autumn (Figure 18). No seasonal significant difference was shown by ash content with respect to with 95% significance level (p<0.05) (Appendix H). Moisture content also varied from dry meat weight basis) during rainy season, which follows in spring (Figure 19). There was no seasonal difference present in moisture content with respect to 95% significance level (p<0.05) (Appendix H).
CHAPTER FIVE
DISCUSSION
The secondary water quality data clearly indicate that low salinity along with high siltation from upstream runoff are responsible for the non-existence of these three species of mollusks in the Noakhali region. Direct field visits were made in the area of Sandwip Island and Shitakunda in Chittagong district, but there was also no sign of oysters. According to the study, it was found that during the rainy season, the huge water comes along with the silt and sand particles from upstream, which makes the region very turbid and muddy, and therefore the mollusc population cannot survive in the unfavorable environment.
According to the collectors, about 50-60 tons of molluscs are collected from this region per year. According to the shellfish collectors in the Khulna region, about thirty boats had five persons each, who collected molluscs from different places in the Sundarban area. According to the middlemen, around 500-550 tonnes of shells are sold to the industry every year from this region.
Oyster shells are also sold to the poultry and tiger shrimp industry to make poultry and shrimp feed. According to the collectors, about 50-60 tons of molluscs were collected in this area (Appendix B). Range of metal concentrations found in oyster muscle in this study (in ppm dry weight).
This change occurred due to changes in environmental parameters such as water salinity, food availability and temperature. Sidwell et al., 1979 reported that variations in fatty acid concentrations at each site may be due to changes in environmental parameters. Amino acid richness in wild oysters was also associated with maximum maturity (Dridi et al., 2007).
The main component of oyster meat is water, which is so tightly bound to the proteins in the structure that it cannot be easily extracted even under high pressure and is an indicator of freshness. Whyte and Englar (1982) reported an average lipid content of 7.35% for tray-grown oysters, while Jeng et al. 1998) reported that the lipid concentration in oysters remained relatively constant compared to other ingredients. During the rainy season, the moisture content is high due to greater intake of water for osmoregulation.
CHAPTER SIX CONCLUSION
RECOMMENDATIONS AND FUTURE PERSPECTIVES
LITERATURE CITED
And Nayak V.N., 2011, Nutritional quality of bivalves, Crassostrea madrasensis and Perna viridis in the kali estuary, Karnataka, India. Seasonal dynamics of phytoplankton and zooplankton in the coastal waters of the Bay of Bengal, Cox's Bazar. Species composition and seasonal dynamics of Diatom and their relationship with some environmental factors in the Moheskhali Canal, Cox's Bazar, Bangladesh.
Seasonal variation in the chemical composition and fatty acid profile of Pacific Oysters (Crassostrea gigas). Reproduction, growth rate and culture potential of the Green Mussel, Perna viridis (L.) In Edaiyur Backwaters, East Coast of India. M., 2010, Abundance, distribution and culture potential of three commercially important mollusc species along the Bay of Bengal coast. Journal of Agricultural and Biological Sciences.
Fish as food: the contribution of aquaculture Ecological and economic impacts and contributions from fish farming and capture fisheries. Seasonal variation in the chemical composition and condition index of Pacific oysters, Crassostrea gigas, grown in hills or on the seabed.
APPENDICES
Appendix E: Seasonal variations of amino acid content of oysters (g/100 g crude protein) Parameters Summer Rainy season Autumn Fall Late Winter Spring.
BRIEF BIOGRAPHY OF THE AUTHOR
