Community analysis of planktonic protozoa following exposure to dispersant only and physically and chemically dispersed crude oil

This study involved a 7 day land-based mesocosm experiment within 120 gallon tanks placed in a temperature controlled water bath. The mesocosm set up is located at UTMSI, Port Aransas, Texas. Natural seawater was pumped from the shipping channel into each tank during an incoming tide to obtain natural plankton communities. Each tank had a gentle aeration system installed to provide mixing and ensure oxygenation levels remain consistent. The experiment was carried out between August 9th and 15th, 2016 during which three treatments were tested alongside a control. All treatments plus the control were tested in triplicate tanks. These treatments consisted of crude oil only at 10ppm, chemically dispersed crude oil at 10ppm (dispersant to oil ratio of 1:20) and dispersant only at the same concentration used in the 10ppm dispersed oil treatment. Samples were collected every 24hrs to analyze protozoan community alterations. Both live and preserved samples were analyzed via microscopy methods. This allowed the examination of daily survival, mortality and potential recovery rates of protozoan species within conditions which best reflect ambient environmental conditions.

本研究开展了为期7天的陆基中宇宙实验（mesocosm），实验容器为置于温控水浴槽内的120加仑水箱。实验装置位于德克萨斯州阿兰瑟斯港的UTMSI。涨潮时，从航道抽取天然海水注入各水箱，以获取自然浮游生物群落。每个水箱均安装温和曝气系统，以实现水体混合并确保溶氧水平稳定。实验于2016年8月9日至15日进行，期间测试了三种处理组及一组对照组。所有处理组与对照组均采用三重复水箱设计。处理组包括：仅添加10ppm原油组、添加10ppm化学分散原油组（分散剂与油的比例为1:20），以及仅添加与10ppm分散原油处理组浓度相同的分散剂组。每24小时采集一次样本，以分析原生动物群落的变化。活样本与固定样本均通过显微镜法进行分析。这使得研究人员能够在最接近自然环境条件下，考察原生动物物种的每日存活率、死亡率及潜在恢复率。