Ecological assessment of fish biodiversity in relation to hydrological variables in Ogun Coastal Water, Ogun State, Nigeria

Abstract

This research analysed the fish species diversity; ecological distribution and abundance in relation to hydrological variables of Ogun coastal water. Fish species were collected with the use of graded gillnet bimonthly for six-months. Correlation analysis between fish species richness with the hydrological attributes showed good relationship; nitrate (17.14mg/l), salinity (30.95mg/l), dissolved oxygen (6.74mg/l) and temperature (28.43^oC) were found the most important variables in determining fish abundance. A total of 21 fish species belonging to six orders, 12 families and 18 genera were recorded. Clupeids (47.1%) were the most dominated group followed by Carangid (16.53%) and Sciaenid (10.44%). The Perciformes was found to be the most predominated order constituting 48.3% of the total 6 order. Shannon-Weiner diversity index showed considerable variation and ranged from 1.26 to 2.27; while monthly diversity indices showed that the fish taxa was least in March (12) and highest in June (19). Dendogram result identified seven distinct groups which suggest closer ecological similarities in the study area. Variation in fish species diversity and richness indicated that the water quality variables strongly determine the abundance of fish fauna and the exhibited level of fish diversity provides a precise set of structural basis for this research.

Keywords: Biodiversity, hydrological, coastal, ecology, fish