Temperature-dependent effects of the Brazilian oil spill to early life stages of <i>Danio rerio</i>

Exposure of fish early life stages to polycyclic aromatic hydrocarbons (PAHs) causes negative impacts on development of teleost fish, which can be exacerbated by rising global temperatures. This study investigated the combined effects of exposure to oil water accommodated fractions from the spill that affected the Brazilian northeast and rising temperatures on early development of the zebrafish Danio rerio. Exposure to PAHs caused developmental delay and increased frequency of malformations at 16.47 and 32.95 μg-∑PAHt L-1 at 28 °C, 30 °C, and 32 °C. Incomplete mandible development was not verified after PAH exposure at 28 °C but increased with increasing temperatures. Increased frequency of malformations included thrombosis, deformed heart, pericardial and yolk-sac edemas and spinal kyphosis. Heart rates increased with increasing temperature in control larvae and with increasing PAH concentrations at 28 °C and 30 °C, but not at 32 °C. Total length, eye and swim bladder area of larvae at 168 hr post-fertilization (hpf) decreased with increasing PAH concentrations and increasing temperatures, indicating an additive interaction. Acetylcholinesterase (AChE) activity in control larvae increased with increasing temperatures and decreased with increasing PAH concentrations. Combined exposure to PAHs and temperature elevation intensified developmental delays and teratogenic outcomes, posing additional threats to the viability of Danio rerio early life stages. Results indicate that temperature effects should be considered in oil spill risk assessments under climate change scenarios.