Departments of Biology and Environmental Science & Studies, Washington College, 300 Washington Avenue, Chestertown, MD, 21620, USA.
Arch Environ Contam Toxicol. 2019 Jul;77(1):29-39. doi: 10.1007/s00244-019-00629-6. Epub 2019 Apr 24.
Human activities have introduced a variety of chemicals, including pesticides, fertilizers, and salt, into the environment, which may have deleterious effects on the organisms inhabiting these areas. Amphibians are especially susceptible to absorption of chemical pollutants. To determine the possible combined effects of these chemicals on amphibian development and stress levels, Southern leopard frog (Lithobates sphenocephala) larvae were exposed to one of eight individual or combined treatments of atrazine, ammonium nitrate fertilizer, and sodium chloride salt. Stress levels, indicated by release of the stress hormone corticosterone, were measured premetamorphosis at week 8 of development. Water hormone samples were processed to analyze corticosterone levels. Changes in tadpole growth were determined by surface area measurements taken from biweekly photographs. The combined chemical treatment of atrazine, salt, and fertilizer had a significant interactive effect by increasing stress levels before metamorphosis (p = 0.003). After a month of larval development, tadpoles exposed to ammonium nitrate had larger surface area (p = 0.035). Tadpoles exposed to atrazine had a lower growth rate throughout larval development (p = 0.025) and the lowest number of individuals reaching metamorphosis at 33%. However, the frogs in the atrazine treatment that did successfully metamorphose did so in fewer days (p = 0.002). Because amphibians are exposed to multiple chemicals simultaneously in the environment, assessing the effects of a combination of contaminants is necessary to improve application strategies and ecosystem health.
人类活动将各种化学物质，包括农药、化肥和盐，引入环境中，这可能对生活在这些地区的生物产生有害影响。两栖动物特别容易吸收化学污染物。为了确定这些化学物质对两栖动物发育和应激水平的可能综合影响，南方豹蛙（Lithobates sphenocephala）的幼虫暴露于单独的莠去津、硝酸铵化肥和氯化钠盐或八种混合处理中的一种。在发育的第 8 周（即前变态期）测量应激激素皮质酮的释放，以确定应激水平。对水样激素进行处理以分析皮质酮水平。通过从两周一次的照片中测量表面积来确定蝌蚪生长的变化。莠去津、盐和化肥的联合化学处理通过增加前变态期的应激水平（p=0.003）具有显著的交互作用。在一个月的幼虫发育后，暴露于硝酸铵的蝌蚪的表面积更大（p=0.035）。暴露于莠去津的蝌蚪在整个幼虫发育过程中生长速度较慢（p=0.025），达到变态的个体数量最少（33%）。然而，在莠去津处理中成功变态的青蛙在更短的时间内完成（p=0.002）。由于两栖动物在环境中同时接触多种化学物质，因此评估污染物组合的影响对于改进应用策略和生态系统健康是必要的。
