In the present study efforts have been made to ascertain the seasonal abundance and population dynamics of zooplankton community and its relationship with physico-chemical factors of the water bodies of Santragachi Jheel in the District Howrah, W.B., INDIA. The zooplankton abundance showed distinct seasonal or temporal variation in the Jheels. A total of 18 species belonging to 12 families and 15 genera were recorded. The population density of total zooplankton showed summer maxima in the Jheel. Maximum abundance of rotifer fauna was recorded during summer season in sewage sites whereas Cladocera population showed maximum density at non-sewage sites. Copepods showed postmonsoon maxima in sewage sites in the Jheels. Some species i.e., Polyarthara vulgaris were quite abundant in the polluted water of the Santragachi Jheel. Out of 15 genera of Zooplankton, Brachionus, Keratella, Polyarthra, Diaphanosoma, Ceriodaphnia, Bosmina, Heliodiaptomus and Mesocyclops were found to be dominant in Santragachi Jheel. Highest percentage of similarity was recorded between S1 and S3 sites of the Jheel. Results of ANOVA (2 - way) indicated that zooplankton population differs significantly in relation to stations and seasons of the Jheel. Population of Rotifera, the most dominant group was found to be positively influenced by Biological Oxygen demand (BOD), Free Carbon-di-oxide FCO2), CaCO3 hardness (CaHa), Total suspended solid (TSS), Chloride(Cl) and Phosphate (PO4) in the Jheels. Total Cladocera showed positive correlation with PO4 in the Jheel. The Copepods expressed positive correlation with BOD and ammonia. Increment of population density of several zooplankton organisms (i.e., Keratella tropica, Polyarthra vulgaris) and low value of community indices especially species diversity and species richness indicated the rise of pollutional stress on the Santragachi Jheel. Keywords: Zooplankton; Rotifera; BOD; COD; Shannon - Wiener index; Evenness index DOI: http://dx.doi.org/10.3126/jowe.v5i0.4595 J Wet Eco 2011 (5): 20-39

The results of this investigation clearly indicate that there was a significant (p<0.001) role of dietary salt in the development of hypertension.

A field study of the nest-building behaviour in the breeding season of the Asian Open-Billed Stork, Anastomus oscitans, was conducted in the Kulik Bird Sanctuary, Raiganj, Uttar Dinajpur, West Bengal, India. Observations were made throughout one complete breeding season (2007)(2008) in the sanctuary. The open-billed stork comes in the last week of June at the Kulik bird sanctuary, stays there for 5 to 6 months and leaves the place in the month of December of every year. From the present observations it was noticed that about 58920 storks came to Kulik during 2008. Various types of behaviour were observed during this particular period. Coming to the Kulik, pairing of the individual storks start and mating display was observed within a day or two. Birds of a pair supplied the nest building materials to form the nest. To give a definite shape to the nest it took about 12-15 days before egg laying. The nesting territory consisted of a semicircle, some times circular and approximately with 30.21 ± 0.12 cm radius. The depth of the nest was about 6.9 ± 0.02 cm. The nest building materials consisted of fragments of old branches of trees, some soft green leaves and grasses. These branches helped in strengthening and the leaves and grasses helped in softening of the nest. During the incubation period both sexes were involved to incubate the eggs. Nest attendance of the breeding birds was continuous during the first 2-months period. From regular observation it was noticed that either of the pair took additional care by spreading their wings during the time of heavy sunshine or heavy rain. The main behavioral patterns examined were aerial displays, mating pattern, nest building, egg laying and incubation pattern, nest defense and nest protection. Diversity of nesting behavior in openbilled stork was pointed out and discussed.

To observe the complementary effects, whole body of the male wild Indian house rat, Rattus rattus was irradiated with X-rays at 100 r, 200 r, 300 r and 500 r (single dose) doses. The changes in the histophysiological parameters of the testis were observed after 2, 7, 15 and 30 days of post treatment. Determination of biochemical parameters: ascorbic acid, cholesterol, acid and alkaline phosphatases in the testicular tissues indicated that concentrations of ascorbic acid and cholesterol (2 to 15 days post treatment) had increased while acid and alkaline phosphatases (2-30 days) had decreased. Changes in these parameters were observed in all four X-ray treated groups (100 r, 200 r, 300 r and 500 r). The histochemical study of the different X-ray treated groups clearly showed the intense accumulation of lipid substances and depletion of acid, alkaline phosphatases, 5-3-HSDH and 17-HSDH in the testicular tissues of 7 to 30 day-post treated groups exposed to 300 r and 500 r X-irradiation. In view of the changes observed in the testicular tissues, it is likely that a single dose of X-ray may cause certain histophysiological changes in the testis of wild rodents at least for certain periods. As a single dose of Xrays of 200r or 300r was sufficient to cause sterility in male rats, this may be included as a controlling agent that adversely effect the fertility of the rodent pests. Possible mode of action is discussed.

The present study deals with the seasonal limnological investigation related to physico-chemical characteristics of water of the Santragachi and Joypur Jheel, West Bengal, India. Besides temperature and meteorological data, 17 limnological parameters were tested following standard methods at 3 sampling sites/stations of each Jheel. The physico-chemical parameters (transparency, pH, DO, BOD, COD, free CO2, total alkalinity, conductivity, CaCO3, TSS, TDS, Chloride, Ammonia, Nitrite, Nitrate, Phosphate, etc.) showed distinct temporal or seasonal variation in both the Jheels. Higher nutrient contents (nitrate, phosphate) are present in Santragachi Jheel. This finding also signifies eutrophication/higher trophic level. Water transparency, dissolved oxygen, BOD, total alkalinity, conductivity, CaCO3 hardness, TSS, nitrate and phosphate was correlated with various physico-chemical parameters in both the Jheels.  The physico-chemical characteristics of water of the two Jheels revealed the poor water quality in Santragachi Jheel than the Joypur Jheel. These characteristics showed maximum contamination of water due to sewage effluents in Santragachi Jheel. The two years (February, 2000 - January, 2002) survey reflects higher degree of pollution in Santragachi Jheel.DOI: 10.3126/on.v8i1.4328