Assessment of physico-chemical characteristics and phytoplankton community in selected aquaculture ponds in Karnataka

Abstract

The site characteristics include present land use, vegetation and land topography of the fish ponds were investigated based on visual field observation. Physico-chemical and biological characteristics of water from selected aquaculture ponds were assessed. The results showed variation in different water quality parameters. The water temperature ranged from 24.30 to 32.10 oC, pH from 5.60 to 9.35, Transparency from 7.1 to 30.40 cm, Dissolved oxygen from 3.1 to 11.34 mg/l, Alkalinity from 24 to 166 mg/l, Carbon dioxide from 1.11 to 13.74mg/l, Ammonia-nitrogen from 0.29 to 18.65 µg at./l and Phosphate-phosphorus from 0.21 to 5.34 µg at. /l. All the parameters were found within the optimum range recommended for fish culture. A total of 3 genera of phytoplankton (Cyanophyta, Chlorophyta, and Bacillarophyta) were found dominant groups. The quantitative and qualitative analyses of phytoplankton showed that plankton content was moderate. Chlorophyta and Cyanophyta dominated the phytoplankton biomass. Microcystis spp. was the dominant among the blue green algae whereas, green algae was mainly consisted of Pediastrum, Ulothrix and Cyclotella. The maximum Ulothrix number was recorded in all the selected ponds while Pediastrum contributed to the bulk of green algae in all ponds during the study period.