Effects of crude oil on the gastropod, tympanotomus fuscata in the Cross River Estuary, south-east Nigeria

Abstract

Edible periwinkle, Tympanotonus fuscata, was collected from the Cross River estuary, allowed to acclimate to laboratory conditions for a week and then exposed to Nigerian light crude oil at different concentrations of 50ml, 100ml, and 150ml per litre of water for a period of 96 hours. Mud (80g) was added to all the 4-litre aquaria used for the experiment. The oil was thoroughly mixed with the estuarine water by stirring vigorously. During the 4-days experimental period, most of the specimens suffered suffocation and became moribund and mortality recorded. Within the first 24 hours mortality was absent in the 50ml and 100ml concentrations, although most specimens moved out of the medium by creeping up the aquaria. Specimens in the control seemed lively and unaffected by oiling throughout the duration of the experiment. Mortalities were as high as 117 out of 180 individuals during the entire experimental period, with higher concentrations recording higher mortalities. There was steady increase in mortality from 4 individuals in the first 24 hours to 12 individuals after 72 hours in the 150ml/l concentration. The LC 50 values were obtained by graphical interpolation. It is concluded that the soluble fraction of the Nigerian light crude oil could be detrimental to shellfish even at a concentration as low as 1000ml/l of the estuarine water.

Quantal Response of Periwinkle (Tympanotonus fuscatus) after Exposure to Kerosene

“…As deposit feeders, periwinkles may have incorporated part of the dissolved components of the kerosene into its tissues [16] which eventually may have altered the normal body physiology and biochemistry of the periwinkle, thereby leading to death. The mortality pattern in this study is in accordance with the findings of [4,13,16] who observed that mortality of periwinkle from petroleum products depends on the concentration of the products and duration of exposure. The kerosene prevents gaseous exchange between the respiratory organs and the affector sites thereby hindering the oxygen changing capacity of the periwinkle which lead to death [17].…”