MONITORING OF ARTEMIA SP. IN THE HYPERSALINE LAKE KARACHI

Abstract

The researchers investigated the water temperature in the Lake Karachi in the middle of March where it reached 20оС below 0. The mineralization of brine varied greatly: from the lowest parameters in October (98.0 g/l) to the highest parameters in March (271.5 g/l). The authors observed indirect relation between water mineralization and temperature: correlation of the open water period was-0.820. The number of nauplius larvae and codepods Artemia sp. appeared in the brine in the middle of April was high until the end of June whereas it was reduced in the second part of the summer and disappeared in October. Artemia sp. females were observed from the middle of May to the end of September. The highest number of females was observed in July - 5.6 thousands samples/m3. The males were observed in the Karachi Lake in the end of September - 0.2 thousands samples/m3. The relation between females and males in that period was 1:3, seasonal average correlation - 1:69. The cysts of Artemia sp. were observed in the water column and sludge deposits. The dynamics of the number and biomass of plankton and bottom cysts is synchronic during the whole year. The number of bottom cysts varied from 0.3 to 22.6 million samples/m2, biomass - from 1.5 to 113.0 g/m2. The highest number of plankton cysts was observed in June (169.875), the average number was - 73.341 thousands samples/m3, maximal biomass - 0.849 g/m3, the average biomass - 0.367 g/m3. The number and biomass of all cod stages related to the water temperature: correlation coefficient of cysts was 0.88, nauplius - 0.58 and females - 0.69. The number and biomass of males related indirectly to the water temperature (r = - 0,52).