The effects of co-exposure of Australian crude oil and ultraviolet radiation to yellowtail kingfish (Seriola lalandi) and black bream (Acanthopagrus butcheri) on hatching success and cardiac development

Yellowtail kingfish (Seriola lalandi) and black bream (Acanthopagrus butcheri) embryos were co-exposed to Australian crude oil and ultraviolet radiation at different points in development, and the effects were quantified on the hatched larvae. For each experiment, a high energy water accommodated fraction (HEWAF) of Australian crude oil at a loading rate of 1 g/L was prepared. Fish were exposed to dilutions of the HEWAF and either 10% or 100% ultraviolet radiation (outdoor sunlight) in a temperature controlled water bath to ensure temperatures in the exposure dishes did not exceed 25°C. Yellowtail kingfish embryos were exposed to dilutions of the HEWAF for approximately 32 hours, and then co-exposed to UV radiation for 4 hours. Following the UV exposure, the embryos were transferred to clean water and held at normal laboratory conditions (25°C, 14:10 light dark cycle) until hatch. At 48 h, hatching success, heart rate, incidence of edema were quantified. Images were taken of the larvae using a Leica M205C stereomicroscope to quantify pericardial edema using ImageJ (v1.49). Another experiment was conducted on yellowtail kingfish later in development. The embryos were exposed to oil for approximately 21 h during which hatch occurred, then co-exposed to UV radiation for 2.75 h as larvae. Following the exposure, the larvae remained in the exposure solution in normal laboratory conditions. Survival was quantified at 72 h and images were taken to quantify pericardial area using ImageJ (v1.49). Black bream embryos were exposed to dilutions of the HEWAF for a total of 4 h. After 2 h of oil exposure, the embryos were then co-exposed to UV radiation for 2 h. Following the UV co-exposure, embryos were transferred to clean water and remained in normal laboratory conditions until hatch. At 24 h, hatching success, heart rate, incidence of arrhythmia were quantified. Images of the hatched larvae were taken to quantify pericardial edema in ImageJ (v1.49).