Combined Developmental Effects of Environmental Stressors and Polycyclic Aromatic Hydrocarbons on Fundulus grandis Larvae

Oil spills have polluted the marine environment for decades and continue to be a major source of polycyclic aromatic hydrocarbons (PAHs) to marine ecosystems around the globe. Although the toxicity of PAHs to fish has been well studied, the combined effects of extreme abiotic factors and oil are poorly understood. Gulf of Mexico killifish Fundulus grandis larvae (< 24 hours post hatch) were exposed to varying environmental conditions (dissolved oxygen 2, 6 ppm; temperature 20, 25, 30°C; and salinity 3, 10, 30 ppt) combined with varying concentrations of high energy water accommodated fractions (HEWAF) (total PAHs 0 – ~ 125 ppb) for a total of 48 h. Larvae survival and development were negatively affected by PAHs, starting with the lowest concentration tested (~15 ppb). High temperature + hypoxia + PAHs resulted in the lowest survival with salinity having little impact on any of the endpoints tested. Expression of the hepatic detoxifying gene cyp1a was highly induced in PAH-exposed larvae, but only under normoxic conditions. A lack of cyp1a induction under hypoxia and PAH exposure could explain the enhanced toxicity observed. This work highlights the need for more studies examining the combined impact of suboptimal water quality parameters in the presence of pollution in fish early life-stages. Gulf of Mexico killifish Fundulus grandis larvae (< 24 hours post hatch) were exposed to varying environmental conditions (dissolved oxygen 2, 6 ppm; temperature 20, 25, 30°C; and salinity 3, 10, 30 ppt) combined with varying concentrations of high energy water accommodated fractions (HEWAF) (total PAHs 0 – ~ 125 ppb) for a total of 48 h.

数十年来，石油泄漏持续污染海洋环境，仍是全球海洋生态系统多环芳烃（polycyclic aromatic hydrocarbons，PAHs）的主要排放来源。尽管多环芳烃对鱼类的毒性已得到充分研究，但极端非生物因子与石油的联合效应仍未得到充分阐释。
本研究以孵化后不足24小时的墨西哥湾大底鳉（Fundulus grandis）幼体为实验对象，将其暴露于不同环境条件[溶解氧2、6 ppm；温度20、25、30℃；盐度3、10、30 ppt]与不同浓度高能水可溶组分（high energy water accommodated fractions，HEWAF，总PAHs含量为0~约125 ppb）的复合环境中，总暴露时长为48小时。
实验结果显示，多环芳烃会对幼体的存活率与发育产生负面影响，最低测试浓度（约15 ppb）即可引发此类不良影响。高温、低氧与多环芳烃的三重复合条件下，幼体存活率降至最低，而盐度对所有测试终点均几乎无影响。
暴露于多环芳烃的幼体肝脏解毒基因cyp1a的表达水平显著上调，但该诱导现象仅出现于常氧条件下。低氧与多环芳烃共同暴露时未出现cyp1a的诱导表达，这一结果可解释观测到的毒性增强效应。
本研究凸显了开展更多相关研究的必要性，以探究鱼类早期生活史阶段中，污染存在时亚优水质参数的联合生态影响。
本研究再次以孵化后不足24小时的墨西哥湾大底鳉幼体为实验对象，将其暴露于不同环境条件[溶解氧2、6 ppm；温度20、25、30℃；盐度3、10、30 ppt]与不同浓度高能水可溶组分（总PAHs含量为0~约125 ppb）的复合环境中，总暴露时长为48小时。