Seasonal Variation in the Physicochemical Characteristics and Microalgae of Selected Mangrove Ecosystems in Ernakulam

The present study was carried out to determine the physicochemical characteristics of water and the diversity of microalgae in three different mangrove ecosystems of Ernakulam district for a period of one year. Surface water temperatures varied from 30 0 C to 32 0 C. The pH ranged from 7.1 to 8.4 at all the stations during the course of study. The variation in the dissolved oxygen ranged from 0.48 to 1.28 mg/l, carbon dioxide from 0.88 to 3.6 ppm, alkalinity ranged from 15 to 20 ppm and the dissolved chloride ions ranges from 7.28g/l to 8.07 g/l. Concentrations of nutrients viz. phosphate (10.3 to 93.6 μg/l), nitrate (28.6 to 110.6 μg/l), varied independently their concentration recorded its maximum during the post monsoon period at all the stations studied. The presence of 18 different genera from Cyanophyceae, Chlorophyceae and Bacillariophyceae was recorded in the three stations. Oscillatoria, Chlorella and Navicula were the dominant species at all the three stations investigated.