Lethal and Sub-Lethal Effects of the Water-Soluble Fraction of a Light Crude Oil on the Planktonic Copepod Acartia tonsa

Abstract

In this study the acute and sub-lethal effects caused by the Water Soluble Fraction (WSF) of a light crude oil were assessed for the first time on the planktonic copepod Acartia tonsa. Chromatographic analysis was also performed to quantify the levels of hydrocarbons (total, aliphatic and polyaromatic hydrocarbons) to which copepods were exposed to. Male and female individuals were exposed to hydrocarbon concentrations varying from 12 to 196 μg.L–1 (Total hydrocarbons). The LC50 was 69.5 (24 hours) and 48.0 μg.L–1 (48 hours) for females and 84.8 (24 hours) and 70.1 μg.L–1 (48 hours) for males. Sub-lethal effects were also evaluated by exposing females to the equivalent of LC10. Females showed significant reduction in egg and fecal pellet production, and also a delay in the eggs hatching time. Thus, the toxic effects of WSF of oil may be crucial for the specie population maintenance, possibly influencing the equilibrium of marine ecosystems.