Dynamics of the chlorophycean populations in a Lagoon bordered by heavy industry, Lagos, Southwest, Nigeria

Abstract

CLARKE, Edwin O, JIMOH, Abayomi A, ADEBOYEJO, Akintade O

An investigation into the dynamics of the population of the green algae (Chlorophyceae) in Ologe lagoon was carried out from January, 2018 to December, 2019. The study covered identification, temporal abundance, spatial distribution and diversity of the (Green algae). These were correlated with variations in some physical and chemical parameters in the lagoon. Eleven sample stations, including Five villages (Idoluwo, Oto, Ibiye, Obele, and Gbanko) bordering the lagoon, were sampled using standard techniques. Data obtained were statistically analyzed using linear regression and hierarchical clustering. Thirteen (13) species of the Class Chlorophyceae were identified and there were positive, significant correlations between them and physical and chemical parameters (surface water temperature and conductivity).The presence of Organic Matter Content (OMC) showed, via partial regression plots, positive correlations at sample stations 2 (Rsq = 0.038), 4 (Rsq = 0.290), 6 (Rsq = 0.095), 7(0.4392), 10 (Rsq = 0.190) and 11 (Rsq = 0.046).The population increased correspondingly with NO3-N at Ibiye (Rsq = 0.0218) and Gbanko (Rsq = 0. 0132). The relationship was positive with the concentration of phosphate-phosphorus (PO4-P) at Ibiye (Rsq = 0.2574). The population was indifferent to the concentration of PO4-P at Oto (Rsq = 0.0000), while it dropped with a corresponding increase in PO4-P at Idoluwo (Rsq = 0.1300) and Gbanko (Rsq = 0.0228).Potassium(k) was observed to favor the green algae at Idoluwo (Rsq = 0.2941). There was also a positive correlation with Sulphate-sulphur (SO4-S) at Oto (Rsq = 0.0957) and Gbanko (Rsq = 0.4560).The hierarchical cluster analysis, revealed two main clusters with all the species except Tribonema occupying the first cluster (the richest), which is divided into eight sub-clusters. Meanwhile, the Spirogyra and Selenastrum species, displayed the greatest similarity or homogeneity, on the rescaled distance cluster. The green algae showed a polymictic distribution and had no prevalent species. The results revealed a narrow spectrum in diversity of Chlorophycean species which were patchy in spatial distribution, undergo seasonal perturbations and were highly influenced by nutrient imputes from bordering towns including Ibiye, Oto, Gbanko, Idoluwo, Agbara industrial estate and surrounding farmlands.