Environmental characteristics of a brackishwater
Manikandavelu
Environmental characteristics of a brackishwater by D. Manikandavelu - M. F. Sc - Thoothukudi Fisheries College and Research Institute 1985 - 87p
Include reference
"The thesis discussed in detail meteorological features of the study area and provides a better picture of the spatial and temporal variations in basic hydrographical parameters, essential plant nutrients and primary production. The study was carried out for a period of one year in mangrove water, which opens in the Tuticorin bay. Two stations i.e., one at the mouth region and the other in the upstream region were fixed for the present study. The difference between the two stations is around 1 km. During the study period salinity showed a range of variation between 12.7 and 42.2% with a bimodal type of oscillation in temporal distribution. In this biotope dissolved oxygen varied between 2.3 and 7.9 ml/l. Generally, during summer months (April to June) super saturation of oxygen and consequent AOP (Apparent Oxygen Production) was prevalent in this mangrove water. Water was generally alkaline and pH of the water oscillated around a mean pH of 7.9. Secchi depth indicated high light penetration during summer months and euphotic zone almost extended upto the bottom throughout the study period. A wide range of variation was observed in light extinction coefficient value. Biochemical oxygen demand (BOD) and chemical oxygen demand (COD) of the water samples were analysed for seven months. The range of variations observed in COD and BOD were from 13.60 to 44.00 mg/l and from 1.50 to 16.05 mg/l respectively. Particulate mattercontent of the water showed a range of variation between 42.80 and 127.50 mg/l. The values of particulate organic carbon fluctuated between 0.98 and 2.82 mg/l. Available nitrogen (NO-3 - N +NO-2 - N + NH3 - N) seasonally varied between 4.56 and 48.36 �g-at N/l and during most of the period contribution by ammonia was high (2.5 to 30.81 �g-at NH3 N/l). Nitrogen seemed to limit plant production, when the ratio of nitrate to phosphate was considered. Phosphorus became the limiting nutrient when the ratio of available nitrogen to phosphate was considered. The domination of ammonia in this biotops could be attributed to the effect of the heavily industrialized area through which the mangrove water receives its freshwater. Silicon showed a significant negative correlation with salinity. High oxygen demand indicated rather continuous higher rate of mineralization of organic matter. Primary production was maximum in this biotope during December and April. The highest value recorded was to the tune of 526.88 mg C/m3/hr. Seasonal maxima in chlorophyll 'a' well coincided with the primary and secondary maxima in primary production. Diurnal variations observed in some essential hydrographical parameters indicated that due to the high oxygen demand during night hours the predawn oxygen values were for below the oxygen level (5 ppm) fixed for fish culture practices. "
Brackishwater - Characteristics
639.32
Environmental characteristics of a brackishwater by D. Manikandavelu - M. F. Sc - Thoothukudi Fisheries College and Research Institute 1985 - 87p
Include reference
"The thesis discussed in detail meteorological features of the study area and provides a better picture of the spatial and temporal variations in basic hydrographical parameters, essential plant nutrients and primary production. The study was carried out for a period of one year in mangrove water, which opens in the Tuticorin bay. Two stations i.e., one at the mouth region and the other in the upstream region were fixed for the present study. The difference between the two stations is around 1 km. During the study period salinity showed a range of variation between 12.7 and 42.2% with a bimodal type of oscillation in temporal distribution. In this biotope dissolved oxygen varied between 2.3 and 7.9 ml/l. Generally, during summer months (April to June) super saturation of oxygen and consequent AOP (Apparent Oxygen Production) was prevalent in this mangrove water. Water was generally alkaline and pH of the water oscillated around a mean pH of 7.9. Secchi depth indicated high light penetration during summer months and euphotic zone almost extended upto the bottom throughout the study period. A wide range of variation was observed in light extinction coefficient value. Biochemical oxygen demand (BOD) and chemical oxygen demand (COD) of the water samples were analysed for seven months. The range of variations observed in COD and BOD were from 13.60 to 44.00 mg/l and from 1.50 to 16.05 mg/l respectively. Particulate mattercontent of the water showed a range of variation between 42.80 and 127.50 mg/l. The values of particulate organic carbon fluctuated between 0.98 and 2.82 mg/l. Available nitrogen (NO-3 - N +NO-2 - N + NH3 - N) seasonally varied between 4.56 and 48.36 �g-at N/l and during most of the period contribution by ammonia was high (2.5 to 30.81 �g-at NH3 N/l). Nitrogen seemed to limit plant production, when the ratio of nitrate to phosphate was considered. Phosphorus became the limiting nutrient when the ratio of available nitrogen to phosphate was considered. The domination of ammonia in this biotops could be attributed to the effect of the heavily industrialized area through which the mangrove water receives its freshwater. Silicon showed a significant negative correlation with salinity. High oxygen demand indicated rather continuous higher rate of mineralization of organic matter. Primary production was maximum in this biotope during December and April. The highest value recorded was to the tune of 526.88 mg C/m3/hr. Seasonal maxima in chlorophyll 'a' well coincided with the primary and secondary maxima in primary production. Diurnal variations observed in some essential hydrographical parameters indicated that due to the high oxygen demand during night hours the predawn oxygen values were for below the oxygen level (5 ppm) fixed for fish culture practices. "
Brackishwater - Characteristics
639.32