Effect of waste engine oil on phytoplankton of the Calabar River Estuary, Nigeria

Abstract

The effect of waste lubrication oil on phytoplankton of the Calabar River Estuary has been examined under static conditions in the laboratory. Significant growth inhibitions and growth pattern alterations as well as susceptibility to bacterial attack were observed in the dominant diatom species- Actinocyclus and Aulocadiscus species during a 5 day exposure to concentrations of the oil ranging from 14.5 to 58 ppm. Oil treatment also resulted in growth enhancements in nanoflagellate population. Considering the importance of diatoms to organic carbon and oxygen supply in the Calabar River and associated Cross River Estuary, their destruction by oil and/succession by flagellates will result in negative consequences for fisheries and overall ecology of the system. The high toxicity of the waste oil even at low concentrations of total hydrocarbons calls for a re-appraisal of the permissible levels of total hydrocarbons in Nigerian inland waters currently put at 10 ppm.



Key Words: Waste lubricating oil, Phytoplankton, toxicity, Calabar River Estuary.

[Global Jnl Environ Sci Vol.2(2) 2003: 112-117]