Núcleo de Estudos do Mar, Universidade Federal de Santa Catarina, C.P. 476, 88.040-900, Florianópolis, SC, Brazil.
Environ Monit Assess. 2010 Aug;167(1-4):65-78. doi: 10.1007/s10661-010-1518-0. Epub 2010 Jun 5.
This paper assesses the effects of non-aqueous fluids (NAF)-associated drill cuttings discharge on shelf break macrobenthic communities in the Campos Basin, off the southeast Brazilian coast, Rio de Janeiro State. Samples were taken with a 0.25-m2 box corer from surrounding two oil and gas wells on three monitoring cruises: before drilling, three months after drilling, and 22 months after drilling. Statistical methodologies used Bayesian geostatistical and analysis of variance models to evaluate the effects of the NAF-associated drill cuttings discharge and to define the impact area. The results indicated that marked variations were not observed in the number of families between cruises, though there were changes in the fauna composition. The changes seen in biological descriptors in both control and background situation areas were not considered significant, showing a temporal homogeneity in means. The impact area presented changes in biological descriptors of communities and trophic structure during the three cruises and such changes were correlated to chemical and physical variables related to the drilling activities, as a result of the mix of drill cuttings and sediment and the anoxic conditions established in the substrate. In that area, three months after drilling, a decrease in diversity and an increase in density, motile deposit-feeders and Pol/Crp ratio, and dominance of opportunistic organisms, such as the capitellid Capitella sp., were observed and, 22 months after drilling, an increase of diversity, reduction of dominance of capitellid polychaete, changes in the fauna composition, and a dominance of opportunistic burrowing and tube-building organisms were observed, indicating an ecological succession process.
本文评估了非水相流体（NAF）相关钻屑排放对巴西东南海岸里约热内卢州坎波斯盆地陆架断裂大型底栖动物群落的影响。在三次监测航行中，使用 0.25 平方米的箱式采样器从周围两个石油和天然气井中采集样本：钻井前、钻井后三个月和钻井后 22 个月。统计方法采用贝叶斯地质统计和方差分析模型，以评估 NAF 相关钻屑排放的影响，并定义影响区域。结果表明，航行之间的科数没有明显变化，尽管动物群组成发生了变化。在对照区和背景区，生物指标的变化都不被认为是显著的，表明平均值在时间上具有同质性。在三个航次中，影响区的群落和营养结构的生物指标发生了变化，这些变化与与钻井活动相关的化学和物理变量有关，这是由于钻屑和沉积物的混合以及底物中建立的缺氧条件造成的。在该区域，钻井后三个月，多样性降低，密度、运动沉积物摄食者和 Pol/Crp 比增加，以及机会主义生物（如头索纲 Capitella sp.）的优势增加，而钻井后 22 个月，多样性增加，头索纲多毛类的优势减少，动物群组成发生变化，以及机会主义的挖掘和管状生物的优势增加，表明存在生态演替过程。
