Flora composition of phytoplankton as bioindicators of water quality in Jakara dam, Kano state, Nigeria

Abstract

A study on phytoplankton as bioindicators of water quality in Jakara Dam was carried out for a period of 12 months (March, 2013-February 2014). Phytoplankton and water samples were collected and analyzed using standard methods. Sampling sites designated as A, B, C, D, and E were chosen. Physico-chemical parameters showed temperature, secchi disk transparency, pH, and electrical conductivity ranged between 25.3-23.9, 10.7-57.9 cm, 7.9-7.7 and 856.7- 817.9μs/cm respectively, so also dissolved oxygen, biochemical oxygen demand, nitrate and phosphate ranged between 4.5-3.3 mg/l, 2.5-1.7 mg/l, 23.8-14.3 mg/l, and 15.8-12.5mg/l respectively. Cyanophyceae were the most dominant contributing 56.8% of the total flora composition, followed by Bacillariophyceae (23.2%) and Chlorophyceae (23.0%). A combined total of 23 species of phytoplankton were encountered. Cyanophyceae 9, Bacillariophyceae 7 and Chlorophyceae 7. The total flora count obtained was 3255.93 Org/l. The highest phytoplankton density was recorded at site D (870.18 Org/l) and lowest at site A (454.39 Org/l). Oscillatoria spp. had the highest total species count (1131.58) org/l while Anthophysa vegetans had the lowest (10.53 Org/l). High percentages of organic pollution indicators Oscillatoria spp and Microcystis aerogenosa were signs of deteriorating condition of the water quality. Shannon - Weiner’s and Evenness Indices values were higher in the months of wet season than in dry season, while the Simpson’s Index values were low. The total flora counts were higher in dry season. In the wet season, Pearson’s Coefficient analysis showed that there was positive relationship between temperature and nitrate and BOD at P< 0.05. Likewise between DO and phytoplankton, BOD and nitrate and phosphate at P< 0.01. During the period of this study, site A had low secchi disk transparency, high level of nitrate and phosphate. This is due to human activities taking place at the site. Shannon - Weiner’s Index value indicated that the site is more polluted. Government and stakeholders should strengthen their legislation against indiscriminate and improper waste disposal along water-ways, dams inclusive. This will ease inflow and check contamination to a large extent. Keywords : Bioindicators, Indicies, Jakara Dam, Physico-chemical parameters, Phytoplankton