Comparative study of the acute toxicity of anionic surfactans alkyl benzene sulphonate (ABS) and sodium dodecyl sulphate (SDS) on gilthead, Sparus aurata L., eggs.

In the present work we have evaluated the acute toxicity of two anionic surfactants, alkyl benzene sulphonate (ABS) and sodium dodecyl sulphate (SDS) to eggs of gilthead Sparus aurata. At each surfactant concentration, we determined the exposure time required for 50% mortality of the eggs (LT50), surface tension and volume of oil globule in gilthead eggs. Clear dose-response relationships for mortality of gilthead eggs was observed for both toxicants; at 30 mg/L 50% mortality took place at 45 minutes for ABS and 8 minutes for SDS. At this concentration, SDS was almost six times more toxic than ABS (LT50 is compared). However, at 0.3 mg/L 50% mortality occurred after exposures of 535 minutes to ABS and 425 minutes to SDS. Descriptively, our results showed SDS was more toxic than ABS at high concentrations whereas at low concentrations their toxicity was very similar. However, statistical analysis demonstrated there were no significant differences in the toxicity of both surfactants to gilthead eggs. Surface tension value at each concentration of both surfactants was also calculated. We found that these values decreased with increasing concentration of each surfactant, and this trend was more pronounced in solutions of SDS. We also found that the volume of the oil globule of exposed eggs was influenced by surfactants. After exposure, its volume clearly decreased in comparison to controls, mainly in eggs exposed to SDS.