The Effects of Oil-Based Mud (Obm) on the Survival of Periophthalmus barbarus (L) after 96 h

A study of the effects of Oil-Based Mud (OBM) on the survival of Periophthalmus barbarus (mean weight: 7.30±0.01 g) after 96 h was conducted using a non-renewable static bioassay techniques. In the acute study, the experimental fish were exposed in triplicates for 96 h to the following: 0% (control), 2, 4, 8, 10%, respectively of the toxicant (i.e., 1% = 100 ml/L).At P> 0.05 the results from the various concentrations were significantly different as cumulative mortality increased with increased concentration. The 96 hour lethal concentration (LC50) of OBM was 4.1%. The lethal time (LT50) for 2% and 10% of the toxicant were 96.58 h and 62 h. The result from the study implies that the oil –based drilling fluid cannot be described as having low toxicity and being environmentally friendly as suggested by the producers.