Abstract
The regular discharge of produced water (PW) from offshore oil and gas industry installations on a global scale constitutes the largest direct and intentional release of industrial effluent containing oil components into the marine environment. In the present study, we have investigated the molecular and phenotypic relationship between timing of embryonic exposure to PW discharges and toxicological effects related to developmental deformities, biotransformation, lipid homeostasis, bone vasculogenesis and oxidative stress using lumpfish (Cyclopterus lumpus) as a model species. PW was collected at the point of release of a Norwegian Sea offshore oil-producing platform, acidified, extracted, and reconstituted. The exposure solutions targeted a nominal total polycyclic aromatic hydrocarbon (tPAH) concentration of 20 µg/L, and fish eggs were subjected to a 48-h exposure starting at three different timepoints, namely: 0 - 48 h post-fertilization (hpf; DEP1), 38 - 86 hpf (DEP2) and 10 - 12 days post-fertilization (dpf; DEP3). We observed exposure-specific significant effects in heart rate (HR), lipid composition and morphometry in PW exposed embryos. Overall, our data demonstrated that the timing of lumpfish embryonic exposure to PW discharges leads to specific toxicological, physiological, morphological, and other developmental effects related to bone formation, vascular development, and osteogenic differentiation. DEP3 showed unique response patterns, compared to DEP1 and DEP2, suggesting that 10-12 dpf is a sensitive developmental stage for toxicological effects of PW in lumpfish. These effects were correlated with the presence and concentration of PAH compounds in PW. The findings suggest a potential health and developmental impacts on lumpfish and other marine species regularly exposed to PW discharges.