Effect of Crude Oil on African Catfish (Clarias gariepinus) Juveniles in Port Harcourt, Rivers State

Petroleum hydrocarbons continue to pose a significant threat to fish communities in various aquatic ecosystems, including ponds, lakes, streams, and rivers. The indiscriminate disposal of oil-contaminated materials and oil spillage have made these hydrocarbons the primary pollutants in these environments. Crude oil spreads rapidly in water bodies, causing acute or lethal effects on juvenile fishes, which comprise approximately 60% of aquatic fish populations. To investigate this further, a study was conducted on juvenile Clarias gariepinus. One hundred twenty healthy juveniles were randomly placed in 12 plastic aquaria and exposed to varying crude oil concentrations for 96 hours. Water quality parameters and mortality rates were recorded daily. The study revealed alarming results. The crude oil exposure led to reduced dissolved oxygen and water surface blockage, resulting in increased mortality. However, a concentration of 25ml showed a reduced level of mortality, with no further deaths recorded after 96 hours. Physiological changes, including altered skin color and reduced locomotion, were also observed. Additionally, the study found that crude oil impaired feeding behavior and swimming performance within 24 hours of exposure. Mortality rates increased with prolonged exposure, ranging from 24 to 96 hours. Crude oil and petroleum fractions blocked atmospheric oxygen dissolution, limiting oxygen supply and increasing excretory waste products, such as carbon dioxide and ammonia, in the water. Recovery was delayed in treated basins, whereas control basin juveniles developed into post-juveniles. The study revealed significant differences (P<0.05) in the effect of crude oil on the mortality rate of C. gariepinus when exposed to oil pollutants. The findings of this study underscore the devastating impact of petroleum hydrocarbons on fish communities. Urgent measures are necessary to mitigate oil spillage and disposal in aquatic ecosystems to protect these vulnerable populations.