1Department of Zoology, Narajole Raj College, Paschim Medinipur, West Bengal, India;
3Department of Zoology, Vidyasagar University, Paschim Medinipur, West Bengal, India
Received: 07/05/2014; Accepted: 21/05/2014; Published: 12/06/2014
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This proximate study was carried out to determine the seasonal variation of carbohydrate, protein & lipid of common fresh water gastropod Bellamya bengalensis in nine selected study sites of Medinipur. For biochemical analysis, shell of the gastropods were removed, flesh were dried with filter paper to avoid the outer water content. The study revealed that protein was much higher than carbohydrate & lipid (mg %) in all nine study sites in all seasons. Protein (17.20 ± 1.78) carbohydrate (13.12 ± 0.74) and lipid (4.83 ± 0.017) were the maximum during Premonsoon period than to Monsoon & Post Monsoon period. Protein, carbohydrate, lipid were the maximum during Pre-monsoon period than monsoon & post-monsoon period.
Bellamya bengalensis, Medinipur, Monsoon, Nutritional value, Seasonal variation.
Molluscs constitute the second largest invertebrates& most successful group next to insects (Abbot, 1989; Rao, 1989; Bouchet, 1991). The estimate of number of species of mollusca today varies from 80,000 species (Boss, 1973) to 135,000 (Van Bruggen, 1995) of these about 5000 species are fresh water (Abbott, 1989; Seddon 2000). Many fresh water molluscs are important food source for humans such as calms and snails. Not only that freshwater molluscs have been known to play a significant roles in the public and veterinary health and thus need to be significantly exploring more extensively (Supian and Ikhwanuddin, 2002). Molluscs are also one of the larger invertebrate groups in the fresh water habitat of Bangladesh (Baby et al., 2010). Fresh water molluscs play a vital role in the economy and tradition of west Bengal in India serving as a food of more than 80% families. The use of fresh water mollusca as protein-rich food is very much in practice in a number of countries viz-India (Rao and Dey, 1989), Mexico (Garcia-Cabus 1989) Taiwan ,Formosa, The Philippines and Thailand (Baby et al., 2010). Some workers in Bangladesh (Jaman and Jahan, 2003; Mallick 1996) investigated in the role of snails as supplementary feed of prawns.
Seasonal changes in bio-chemical composition of Mercenaria and Mytilus have been reported by many workers (Ansell et al., 1964; De Zwann and Zandee 1972). Several works have been done on littoral molluscs of West Bengal costal belt (Chakraborty and Chowdhury, 1993) and the diversity of freshwater and marine molluscs of Medinipur District (Khalua et al., 2003; Khalua et al., 2008); but nutritional perspective is still not well studied.
The present study was carried out to understand the change in bio-chemical composition (Carbohydrate, Protein, and Lipid) of Bellamya bengalensis through regular collection of this animal from different freshwater ponds of Medinipur district.
The freshwater gastropod , Bellamya bengalensis were collected from different ponds and wetlands of Burigeria (P1) , Sattamali (P2) , Golgram (P3), Srikrishnapur (P4), Harinarayanapur (P5), Chandanpur (P6), Chalkanananta (P7), Kolaghat (P8) and Haldia (P9). *Lat 21° 30’ - 22° 2’ N long. 87° 20’- 88°5’ E+ (figure 1). The collections are made randomly during the period January-2013 to December 2013. Adult Bellamya species (Bellamya sp.) are selected for laboratory experiments. Immediately after bringing to laboratory, the shells of these gastropods are brushed and washed with fresh and clean water to remove algal biomass, mud and other waste material.
Sample preparation and biochemical analysis
For biochemical analysis, shell of the Bellamya sp. was removed and flesh was dried with filter paper to avoid the outer water content. The wet weights of all the tissues were taken to the nearest milligram (mg) and they were immediately transferred to the hot air oven maintained at 90°-100° C. The samples were dried for 3 to 4 days for the complete removal of their water content (Ahirrao and Kulkarni, 2011). Dry weight of all the tissues were taken when all the moisture was removed and no further change in the weight of the dried tissue was noticed. The dried material was powdered and used for analysis.
For biochemical estimations, dry powder was used and its weight was kept practically constant through the experimental work. Carbohydrate was estimated by Kemp et.al. (1954) method, protein was estimated by Lowry et.al. (1951) method and lipid were evaluated by Barns and Blackstock (1975) method.
The data were expressed as mean ± SEM, n=6. The analysis was performed (using a statistical package, Origin 6.1, Northampton, MA 01060 USA) with One-way ANOVA tests, p< 0.05 as a limit of significance.
The estimated protein of Bellamya sp. has been shown in figure 2. Among the nine selected study sites the protein content in the flesh of Bellamya sp. ranging (8.79±0.15) to (17.20 ±a 1.78). It was observed that protein was maximum (17.20 ± 1.78) during pre-monsoon (March – June). It was further noted that the protein content in remained maximum in study site P3 respectively. The present study revealed that in monsoon protein ranged from (10.23 ± 0.27) to (16.98 ± 1.07); during post-monsoon it varied from (8.79 ± 0.15) to (15.55 ± 0.99) and pre-monsoon the P3 due to presence of large number of small Nymphea.
The analysis of nutrients from the flesh of Bellamya sp. results that molluscs are cheap source of protein and as a source of carbohydrate also. Flesh of Bellamya sp. contains moderate amount of carbohydrate. The present study revealed that during pre-monsoon period carbohydrate was maximum (13.12 ± 0.74) and during post-monsoon it was minimum (5.034 ± 0.57). There was very little variation of carbohydrate content between monsoons, and post-monsoon. In pre-monsoon the carbohydrate was maximum (13.12 ± 0.74) in study site P2 and minimum in study site P8 (7.09 ± 0.54) (figure 3).
The flesh of Bellamya bengalensis contain very little amount of lipid. The present study indicated that the lipid content of flesh showed the very small seasonal variation. Lipid was maximum during pre-monsoon and minimum during post-monsoon and moderate amount during monsoon. During pre-monsoon, the lipid was maximum in study site P2 (4.83±0.01) and P1 (4.57±0.57) and minimum in study size P5(2.14±0.07). During post-monsoon it was maximum in study site P3 (2.00±0.06) probably due to the presence of large number of Nymphea and very low in study size P8 (0.89±0.06) due to thermal pollution. During monsoon lipid was the maximum in study site P9 (1.67±0.26) (figure 4).
Enormous literature is accessible on the toxicity of heavy metals, organ pesticides and insecticides etc. in different aquatic animals related to effect on biochemical constituent levels in different tissues of animals but not so far on seasonal variation. Hence the present study was carried out to evaluate the changes during the seasonal variation on nutritional value of Bellamya bengalensis in different area. The present investigation also showed that these gastropods exhibit total protein, carbohydrate and lipid in pre-monsoon period were maximum due to favorable environmental condition in summer.
It was observed that in study site P8, the protein was lower due to the effect of thermal and fly as pollution of Kolaghat Thermal Power Station as well as it was indicated that study site P9 the protein was comparatively less than rest study areas’ due to environmental pollution of Haldia Petrochemicals, Indian Oil Corporation, Mitsubishi etc. and other industries. Other study sites i.e. P1 - P7, the protein content is comparatively high due to less environmental pollution and stress. During pre-monsoon the protein was the maximum as the water level of pond decreased and less activity of the snail and also the effect of environmental temperature.
During monsoon carbohydrate was maximum in study site P4 (12.02±0.94) probably due to the presence of large number of Pisita, and minimum in study site P9 (6.01 ± 0.32) and P8 probably due to the industrial pollution of Haldia and environmental Pollution by Kolaghat Thermal Power Station. In post-monsoon study site P2 carbohydrate was maximum (9.23 ± 0.65) and minimum in study site P8 (5.03 ± 0.57). At a glance carbohydrate showed small variation in the entire study site during monsoon and post-monsoon season.
The present study revealed that there was a significant variation in the bio-chemical composition in the flesh of Bellamya according to seasonal change. The organic substances like carbohydrate, protein and lipid play a key role in different metabolic activities. Protein is the main organic nutrient that serves as the structural part of different body tissues. The present study showed that
protein was maximum during summer season i.e. in the pre-monsoon and very minimum during post-monsoon, probably due to the variation of environmental temperature. It was observed that protein, lipid and carbohydrate were low in post-monsoon probably due to sedentary life without much activity. Similar results were observed by Pandit (2005) in Lamellidens marginalis of Godavari River. The lipid was found to be more during summer season as due to exposure of mantle and foot to high temperature in summer season .Similar results was observed by Shaikh (2011). The present study revealed that in energy conservation the organism would be expected to make compensatory adjustment to both the components of energy gain and energy loss in the fate of changes in the environmental conditions (Vedpathak, 1989).
The present study may conclude that the nutrient i.e. protein, carbohydrate and lipid content in the flesh of Bellamya bengalensis showed the great seasonal variation and were correlated with the changes in environmental factors and aquatic macrophytes also. However, further study is necessary for evaluation of such variation by molecular study.
The authors are grateful to the Narajole Raj College, Medinipur, West Bengal, India for providing the facilities to execute these studies. Authors acknowledge the help, received from the director and scientists of Zoological Survey of India, Kolkata for identification of species. Authors are thankful also to UGC, Govt. of India, India for funding.