The effect of crude oil pollution on macrophyte assemblage in Kporghor River, southern Nigeria

Abstract

A study of the effects of crude oil pollution on macrophyte assemblage was carried out in Kporghor River, Rivers State. Standard procedures were used in data collection. Temperature, total dissolved solutes, dissolved oxygen, pH and electrical conductivity were taken in-situ using Extech multi-parameter equipment while biological oxygen demand was incubated in a BOD bottle and determined using standard methods. Aquatic macrophytes were sampled with 0.5m × 0.5m quadrant and estimates of the percentage cover of each species inside the 0.5 × 0.5 m quadrant was transformed onto a scale based on Braun-Blanquet. The diversity and abundance of the different species were higher in Station (2), followed by station (3) and Station (1) respectively. Bambus vulgaris having a percentage of (29.7%) being the most abundant with percentage abundance, Cyrtospermum senegalense (8.72%), Nymphaea lotus (5.81), Acanthophoenix crinite (4.65%), Pistia stratiotes and Eichornia grassippes (2.91%) respectively. Unidentified species of macrophyte collected from the sampling area accounted for 11.62% species abundance. The result of physico-chemical parameters: temperature (29±0.63oC to 29.15±0.72oC), pH (6.03±0.12 to 6.9±0.15), TDS (36.23±6.82mg/ to 40.05±5.30mg/L), conductivity (4430±792.42μS/cm to 4914.75±569.42μS/cm), DO (5.20±1.20mg/L to 5.50±0.49mg/L) and BOD (3.08±0.94mg/L to 3.40±0.61mg/L). Copper (0.015mg/L) level was below WHO, SON and DPR standards for Cu in water bodies. Cadmium (0.10mg/L), Lead (0.18mg/L) and Nickel (0.28mg/L) concentrations were above WHO permissible limits. The abundance of Bambusa vulgaris (an alien species) suggests its adaptation to the study area. However, mitigation actions are recommended to restore this polluted ecosystem.