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.本研究考察了科里克斯EC 9500A（Corexit EC 9500A，简称C-9500A）单独暴露，以及与非生物、生物因子联合暴露对模式海洋浮游动物褶皱臂尾轮虫（Brachionus plicatilis）的致死效应与行为学影响。在标准养殖条件（盐度17.5ppt、温度24℃、种群密度200只·mL⁻¹）下，通过概率单位分析法（Probit analysis）测定，培养的褶皱臂尾轮虫的24小时半数致死浓度为107 ppm。暴露于100 ppm、150 ppm高浓度药剂的存活轮虫，其游泳速度显著降低，净运动与总运动的比值也有所下降。本研究观察到C-9500A暴露与温度、盐度之间存在显著交互效应：轮虫的高温耐受上限有所降低，盐度胁迫临界值约为25ppt。在暴露周期内调整营养供给丰度，对测试浓度下褶皱臂尾轮虫种群的死亡率无显著影响。本研究结果可为预测不同自然环境下施用分散剂后，海洋浮游动物可能面临的生态结局提供参考依据。