Effects of Exposure Timing on cyp1a Expression, PAH Elimination, and Lipid Utilization in Lumpfish Embryos Exposed to Produced Water

Intentional discharges of produced water from oil productionplatformsto the marine environment contain a complex mixture of toxicants,including polycyclic aromatic hydrocarbons (PAHs). Early life stagesof fish are highly sensitive to petrogenic exposure, and short-termexposure during critical periods of embryonic development may havedetrimental effects on larvae health and survival. However, why differentperiods are more sensitive to exposure than others are not fully understood.Three identical exposure experiments (48 h, approx. 30 mu g/LtPAH, sum 42 PAHs) on lumpfish (Cyclopterus lumpus) embryos were conducted where only exposure timing was varied: 0-48h post fertilization (hpf, starting before chorion hardening), 36-84hpf (starting after chorion hardening), and 240-288 hpf (duringorganogenesis). Total PAH (tPAH) uptake at the end of exposure was5x higher when exposed during fertilization than when exposedlate (during organogenesis). The first evidence of cyp1a induction in lumpfish during embryogenesis was observed after 84hpf. Early exposure affected lipid droplet coagulation, indicatingaltered lipid utilization during embryogenesis. Although no significantimpacts of exposure were observed on hatching success, hatching wasdelayed when exposed at the latest time point. This study shows thatchorion properties, lipid content, biotransformation potential, andtiming of produced water exposure during lumpfish embryogenesis affectedPAH uptake and elimination. Dueto differences in chorion properties and biotransformationability, timing of fish embryo exposure determines PAH uptake andelimination. Exposure timing is critical for PAH uptake and eliminationin fish embryos. Differences in PAH kinetics are associated with chorionproperties and biotransformation potential. The first sign of cyp1a induction in lumpfish embryos was at 84 h post fertilization.Early produced water exposure causes altered lipid droplet coagulationand alterations in fatty acid profiles.

Automated summary

Intentional discharges of produced water from oil production platforms to the marine environment contain a complex mixture of toxicants, including polycyclic aromatic hydrocarbons (PAHs). Early life stages of fish are highly sensitive to petrogenic exposure, and short-term exposure during critical periods of embryonic development may have detrimental effects on larvae health and survival. However, why different periods are more sensitive to exposure than others are not fully understood.