ACUTE TOXICITY ASSESSMENT OF AN OFFSHORE EXPLORATION FLID FOR THE FERTILIZATION SEA URCHIN LYTECHINUS VARIEGATUS

Abstract

In Colombia, oil industry is interested in developing offshore hydrocarbon exploration, activity that causes spills of harmful substances in marine areas. It is essential to understand the effects that those substances may cause in native organisms in the inflence zones. This manuscript proposes an assay with an autochthonous organism from the Colombian Caribbean, that may be used as a bioindicator of contamination. The acute toxicity (CE50) of a flid used in offshore exploration was assessed on basis on the fecundity of the sea urchin Lytechinus variegatus, using as a standard toxic pentahydrated cooper sulfate. The protocol for obtaining the gametes and fecundation was previously standardized with the reference toxic which is used to guarantee and validate its results in terms of effective concentration (CE50). The fecundation percentage should be greater than 85% in order to validate the assay in the control treatment, that was carried out by fecundating 2000 oocytes with 50 x 106 sperms. In each replicate 200 oocytes (10%) were counted in order to determine the percentage of fecundation. The obtained CE50 value of pentahydrate copper sulphate was 20.45 ± 1.90 mg.L-1 and 3649 mg.L-1 ± 400 mg.L-1 corresponding to the suspended particulate phase of mud, which was prepared from a mud-water relationship of 1:9 (v/v). The results show a high sensitivity degree of the L. variegatus gametes to the action of the drilling mud of offshore hydrocarbon exploration, which shows the sensitivity of the test organism to these substances and its potential use as bioindicator of pollution.