Impacts of oil exposure during early life developmental stages in Sheepshead minnows (Cyprinodon variegatus) under different environmental factors

The purpose of this research was to determine windows of increased sensitivity to combined oil and hypoxic exposure under varying salinity regimes during early life stage development of sheepshead minnows. The early life development was divided into three stages: embryonic (< 15 hpf), post-hatch (<10 hph), and post larval (96 hph). Immediately after each transition period sheepshead minnow larvae were exposed to four concentrations of HEWAF (6.25%, 12.5%, 50% and 100% of 1g/L stock solution) under different oxic (2.5 mg/L and >5.0 mg/L) and salinity (10 and 30 ppt) regimes, while temperature was maintained at 30°C. After the 48 h exposure period, larvae were transferred to normoxic clean water to monitor growth and mortality for up to 10 days. The experiments were static experiments with water renewals every 48 hours. Water quality and organism performance were monitored and recorded daily. A sample of 3.5 mL of exposure water was collected from each test chamber during water quality monitoring at 0 h, 24 h, 48 h, and 72 h for fluorescence analysis to measure PAH concentrations. Whole body tissue samples were collected directly after the 48 h exposure period measure relative gene expression and investigate pathway inhibition between the aryl hydrocarbon and hypoxia inducible factor 1-α signaling pathways. Target genes included Cytochrome P450 1A1 (CYP1A1), Erythropoietin (EPO), and Aryl hydrocarbon receptor nuclear translocator (ARNT).