Benjamin Onozeyi Dimowo¹ , Adewole Michael Gbadebo¹ , Adewale Matthew Taiwo¹ , Isaac Tunde Omoniyi²

1 Department of Environmental Management and Toxicology, Federal University of Agriculture, PMB 2240, Abeokuta, Nigeria
2 Department of Aquaculture and Fisheries Management, Federal University of Agriculture, PMB 2240, Abeokuta, Nigeria
Author    Correspondence author
International Journal of Aquaculture, 2018, Vol. 8, No. 26   
Received: 18 Jul., 2018    Accepted: 15 Oct., 2018    Published: 26 Oct., 2018

This is an open access article published under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

The application of biological indicators is a cheaper alternative for quality assessment of surface waters and can be used to complement routine physical/chemical analysis. This study evaluated the ecological integrity of Lower Ogun River using planktonic diatoms. Water and planktonic diatom samples were collected from four sampling stations fortnightly for a period of four consecutive months (March-June, 2015). Water quality parameters including pH, temperature, electrical conductivity, total dissolved solids, dissolved oxygen, chemical oxygen demand, nitrite, nitrate, ammonium, phosphate, sulphide, chloride, iron, manganese, silicate, total alkalinity, total hardness, total suspended solids, transparency and total organic carbon were analyzed using standard methods. Planktonic diatom samples were collected using 55 µm standard hand plankton net and analyzed following standard protocols. Data collected were subjected to descriptive and inferential statistics using PAST and SPSS statistical packages. A total of 54 planktonic diatoms belonging to 11 orders and 3 classes were identified at the study sites with Melosira varians having the highest abundance (3860 individuals/ml). The dominance of Melosira varians was indicative of organic pollution. The ranges of community structure indices were as follows: Shannon-Weaver Index (2.58-3.53), Menhinick index (0.23-0.57), Margalef index (0.97-3.85), Pielou index (0.70-0.96) and Simpson’s dominance index (1.03-1.41). Canonical Correspondence Analysis and Pearson Correlation results showed correlation between physical/chemical parameters, planktonic-diatom abundance, species composition, distribution and community structure at different levels of significance (p<0.05). It was concluded that the quality of the river during the study period ranged between no pollution and slight/moderate pollution.

Applied ecology; Bioassessment; Ecosystem health; Environmental management; Surface water bio-indicators