Acute response of Branchionus spp. (Rotifera) when exposed to Corexit

We examined lethality and behavioral effects of Corexit EC 9500A (C-9500A) exposure on the model marine zooplankton Brachionus plicatilis singularly and in combination with abiotic and biotic factors. C-9500A exposure at standard husbandry conditions (17.5ppt, 24°C, 200 rotifer*mL-1 density) identified the 24 hr median lethal concentration, by Probit analysis, to be 107 ppm for cultured B. plicatilis. Rotifers surviving exposure to higher concentrations (100 and 150 ppm) exhibited a decreased swimming velocity and a reduced net to gross movement ratio. Significant interaction between C-9500A exposure and temperature or salinity was observed. Upper thermal range was reduced and maximal salinity stress was seen as ca. 25ppt. Increased or decreased nutritional availability over the exposure period did not significantly alter mortality of B. plicatilis populations at concentrations tested. Results from this study may be useful for predicting possible outcomes on marine zooplankton following dispersant application under diverse natural conditions.

我们研究了Corexit EC 9500A（C-9500A）暴露对海洋浮游动物模型褶皱臂尾轮虫（Brachionus plicatilis）的致死性及行为效应，包括单独暴露以及与非生物和生物因素联合作用的情况。在标准饲养条件下（盐度17.5ppt、温度24°C、轮虫密度200个·mL⁻¹）暴露于C-9500A时，通过概率单位分析（Probit analysis）发现，养殖褶皱臂尾轮虫的24小时半数致死浓度（median lethal concentration）为107 ppm。暴露于较高浓度（100和150 ppm）后存活的轮虫表现出游泳速度降低及净移动与总移动比率下降。观察到C-9500A暴露与温度或盐度之间存在显著交互作用：其热耐受上限降低，且最大盐度胁迫约为25ppt。在暴露期间，营养可利用性的增加或减少并未显著改变受试浓度下褶皱臂尾轮虫种群的死亡率。本研究结果或有助于预测在不同自然条件下使用分散剂后对海洋浮游动物可能产生的影响。