Abstract:

Photoproducts were generated by irradiating a high energy water accommodated fraction (HEWAF) of Australian crude oil. After a 1 g/L HEWAF was prepared, the solution was diluted to 10% using seawater. The 10% solution was placed in a clear, glass Pyrex baking dish and covered with either aluminum foil (to block UV radiation, referred to as the non-irradiated WAF) or UV transparent plastic (to allow for UV radiation, referred to as the irradiated WAF). The covered dishes were placed under ambient sunlight for 3-5h. After the UV exposure, the dishes were cooled to 25°C and diluted to 0, 0.1, 1, and 10%. Yellowtail amberjack (Seriola lalandi) embryos were exposed to irradiated and non-irradiated WAFs for 48 h in the laboratory (no UV light, 14:10 light dark cycle, 25°C). At 48h, hatch rate was quantified, and five larvae per treatment replicate were randomly selected and heart rate was quantified. Images of the five larvae were taken using a Leica M205C stereoscope and pericardial edema and spinal curvatures were quantified using ImageJ (v1.49). Black bream (Acanthopagrus butcheri) embryos were exposed to the irradiated and non-irradiated WAF dilutions for 48 h. After 48 h, hatching success was quantified in the hatch larvae.

Suggested Citation:

Sweet, Lauren; Roberts, Aaron P.. 2017. Effects of photoproducts generated from irradiated Australian crude oil to the yellowtail kingfish (Seriola lalandi) and black bream (Acanthopagrus butcheri) on hatching success and cardiac development. Distributed by: GRIIDC, Harte Research Institute, Texas A&M University–Corpus Christi. doi:10.7266/N7D50K2S

Purpose:

PAH photo-products have been shown to be more toxic than their PAH parent compounds to some organisms. Ultraviolet radiation is capable of modifying PAHs found in crude oil to contain more oxygen functional groups and change the physico-chemical properties of the PAH molecules. Given the high levels of ultraviolet radiation in the southern hemisphere near Australia, the purpose of this study was to understand the effects of UV irradiated oil to early life stage fish in the surface of the water column.

Data Parameters and Units:

UV treatment (%), Oil treatment (% HEWAF), Replicate, Fish #, Organism hatch rate or survival counts (number of organisms), PAH chemical analysis (pg/mL), Heart rate (number of beats in 15 seconds), ultraviolet radiation measurements (μWatts/cm2), Wavelength (nm)

Methods:

Fish embryos were exposed to high energy water accommodated fractions (HEWAFs) of the northwest shelf 2 crude oil. Approximately 1 g of oil was placed in 1 L of seawater (33 ppt) and blended on high for 30 seconds. Immediately after mixing, the solution was placed into a separatory funnel, capped, and covered in aluminum foil. After one hour of settling, 100 mL of solution was drained from the funnel and discarded. The middle 800 mL of the solution was collected and considered 100% HEWAF solution. This 100% solution was diluted to 10% using ambient seawater (33 ppt). Aliquots of the 10% HEWAF solution and ambient seawater (controls) were placed into 20.3 cm square, glass, Pyrex® baking dishes. The dishes were covered with either UV transparent plastic (termed irradiated WAFs) or aluminum foil (termed non-irradiated WAFs) to ensure minimal evaporative loss. The covered dishes were placed under ambient sunlight for 3-5h. After UV exposure, the dishes were cooled to 25°C. The 10% WAFs were further diluted to 1%, 0.1%, and 0% HEWAF concentrations. A subsample of each dilution was stored in a 250 mL low-density polyethylene wide mouth bottles with a polypropylene screw cap (Thermo Fisher Scientific) at -20°C until photo-product chemical analysis. Ultraviolet irradiance (λ = 380 nm) was measured continuously throughout the UV exposures using a BioSpherical radiometer (BioSpherical Instruments, Inc., San Diego, CA, USA). The yellowtail amberjack toxicity test was performed with a 14:10 light dark cycle at 25°C. After the WAFs were irradiated, cooled, and further diluted, embryos were exposed to the irradiated and non-irradiated WAFs for 48 h in the lab (no UV light). Specifically, ten fish embryos were randomly placed in 250 mL crystalizing dishes containing 200 mL of each WAF dilution with four replicates for each treatment. At 48 h, survival was quantified by placing the embryos under a Leica M205C stereo microscope. Five larvae per treatment replicate were randomly selected and heart rate was quantified during a 15 s time interval. Images of the five larvae per treatment were taken to use for cardiac edemas and spinal measurements. The black bream embryos were maintained at 25°C with a 14:10 light dark cycle. Ten black bream embryos were randomly placed in 250 mL crystalizing dishes containing 200 mL of each WAF dilution with four replicates for each treatment. After 48h of exposure, hatch rate was quantified by placing the embryos under a Leica M205C stereo microscope.

Instruments:

Microscope: Leica M205C Steroscope, Biospherical Radiometer

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