Phytoplankton abundance and distribution of fish earthen ponds in Lagos, Nigeria
The study investigated phytoplankton abundance and distribution under different pond management to determine the effect of some physicochemical parameters on the community structure of three onresearch fish earthen ponds of Nigerian Institute for Oceanography and Marine Research, Badore, Lagos. Samples were taken every week using standard procedure. Water quality parameters; temperature, dissolved oxygen, turbidity, salinity and pH were measured and found to be within the optimal ranges for phytoplankton productivity. Seventeen (17) phytoplankton species belonging to family Chlorophyceae, Bacillariophyceae, Cyanophyceae and Euglenophyceae were identified. Densities of the phytoplankton ranged from 01.85 x 103 cells L-3 to 25.90 x 103 cells L-3 in the ponds; Chlorophyceae being the most abundant. Mean cell densities of the phytoplankton were significantly different (P<0.05). Few phytoplankton species were present in all the Ponds. The spatial distribution of Bacillariophyceae in ponds 1, 2 and 3 were 41.7%, 41.7% and 16.8%, while those of Euglenophyceae were 50%, 50% and 0% respectively. Shannon Wiener diversity index was 1.263 in Pond 1, 1.265 in pond 2 and 1.078 in Pond 3. Pond 1 had the highest phytoplankton percentage (94.11%). Correlation coefficients were calculated for abundance with pH, DO and temperature. Abundance was positively correlated with the temperature variations and levels of DO but negatively correlated with the pH. Results of phytoplankton abundance of the three ponds clearly showed the
influences of the physicochemical factors on diversity, distribution and abundance of phytoplankton which indirectly affects aquaculture potentials.
Keywords: phytoplankton abundance, diversity, distribution, fish earthen ponds, physicochemical