The present study evaluated the embryonic–larval development of sea urchins (Echinometra lucunter) exposed to water-soluble fractions (WSF) of oil spilled on the Brazilian coast in 2019 and recovered post-accident in 2021. In 2019, organisms were exposed to WSF concentrations of 35.01%, 45.51%, 59.17%, 76.9%, and 100%. In 2021, the concentrations tested were 0.88%, 3.30%, 9.42%, 20.71%, 35.01%, 45.51%, 59.17%, 76.9%, and 100%. The EC50-42 h, NOEC, and LOEC were determined, and the concentrations of PAHs and metal(oid)s were analyzed in the 100% WSF. 2019 PAH levels were above regulatory limits, whereas all 16 analyzed PAHs were below detection limits in 2021. Metal(oid) concentrations above regulatory limits were observed for Cd, Cr, Cu, Ni, Pb, Se, Zn, and Au in 2019, and for Fe, Cu, and Se in 2021. Trace elements of emerging concern, for which no safe limits have been established in Brazilian legislation, were detected in both WSF. The EC50-42 h, NOEC, and LOEC indicated reduced toxicity in 2021 (65.42%, 35.01%, and 45.51%, respectively) compared to 2019 (39.45%, > 35.01%, and 35.01%, respectively), with total inhibition of embryo–larval development at 100% WSF in both years. This reduction in toxicity may be related to the absence of detectable PAHs and to changes in the concentrations of specific metal(oid)s in the post-accident WSF.
Pereira et al. (2026) studied this question.