Water is essential for all living organisms in the universe. Chemicals can cause contamination in groundwater near aquacultural activity areas. Keeping in view the hectic aquacultural activity in surrounding locations of Akividu town in West Godavari District of AP, India, it is proposed to assess the chemical and microbial contamination of waters to suggest remedial measures to protect the quality of water for safeguarding the health of the public residing in the nearby habitations who consume these waters for drinking purposes. 16 Groundwater samples were collected and analyzed for assessing the physicochemical parameters viz., pH, Electrical conductivity (EC), Total Dissolved solids (TDS), Total hardness (TH), Total Alkalinity (TA), Na+, K+, Calcium, Magnesium, Chloride, Sulphate, Nitrate and Phosphate, Irrigation parameters like %Na, SAR, KR RSC, and microbial analysis. The study results revealed that the samples were contaminated chemically and also with pathogenic bacteria like Pseudomonas, Citrobacter freundii and Escherichia coli which can cause water-borne diseases. Further, a health survey was carried out to verify the adverse effects to be caused by the chemical and microbial contamination of water on people?s health. The health survey results indicated the sufferings of the people who consume this water for drinking and domestic purposes. The waters are to be treated accordingly to control the chemical and bacterial contamination by using the available treatment methodologies before considering them for drinking purposes.

This study was aimed to investigate the growth characteristics of living diet Platymonas subcordiformis for aquaculture animals and its harmful organism Oxyrrhis marina in co-culture systems to provide experimental evidences for discussing their succession processes. The colour changes of culture media of P. subcordiformis and growth characteristics of O. marina and P. subcordiformis in co-culture were analysed by the combined methods of macro-observation, microscopic examination and microscopic counting. The results showed that with the decrease of the initial density of O. marina cell (0.65×104 cells mL-1, 0.37×104 cells mL-1 and 0.11×104 cells mL-1 in P. subcordiformis culture media), the time that the population of O. marina reached the stationary phase required longer, were 4d, 5d and 7d after inoculated by O. marina, respectively, and the death time of all cells of P. subcordiformis became longer, were 9d, 10d and 12d after inoculated by O. marina, respectively. After inoculation 9d, pale pink appeared in upper layer of culture media of P. subcordiformis in flasks and the density of O. marina was 2.10×105 cells mL-1. The results also indicated that the variation tendency of cell densities of O. marina and P. subcordiformis cultured in aquariums were consistent with that in flasks basically, pink flocs appeared in upper layer of culture media of P. subcordiformis after inoculation 12d and the density of O. marina was 2.10×106 cells mL-1. The experimental results showed that the feeding of O. marina on P. subcordiformis was affected by the initial concentration of O. marina, and P. subcordiformis populations were evolved to O. marina populations during the 15 days culture period, the colour of culture media appeared pale pink to pink depends on density of O. marina was confirmed, too. Also, the colour changes of P. subcordiformis culture media are indications of pollution by O. marina, which will be important for culture process of P. subcordiformis.

In this present study, the effect of salinity and photoperiod on the growth of Nannochloropsis sp. and Tetraselmis sp. was examined to optimize microalgal growth. Different salinities (5, 10, 15 and 20‰) for Nannochloropsis sp. and (10, 15, 20 and 25‰) for Tetraselmis sp. were studied. Both microalgae were cultivated at two different photoperiod cycles (24:0 and 12:12 h light:dark). Maximum growth rates and cell concentrations for Nannochloropsis sp. and for Tetraselmis sp. were achieved at salinities of 10 and 15‰, respectively. In terms of photoperiod, the maximum growth rates and cell concentrations for both microalgae were obtained at photoperiod of 24:0 h light:dark. This study shows that the cell concentrations and growth rates of both microalgae are highly dependent on salinity and photoperiod.