A large-scale oil spill has reached over 3000 km of the NE Brazilian coast since August 2019. The cause and origin of this spill remain mysterious, and the impacts on coastal ecosystems have not been clearly understood so far. Despite the efforts to remove the oil (mainly from local communities), oil stains are still present in beaches, mangroves, and beachrocks. In this short report, we describe the occurrence of the barnacle Chthamalus bisinuatus Pilsbry, 1916 colonizing oil spill stains on intertidal surfaces of beachrocks one year after the first oil records. We quickly assessed oil stains across three different reefs located at the Conde municipality, Bahia (NE Brazil), where the species was identified and its density on oil stains calculated. The occurrence of barnacles in oil stains was restricted to zones in the wake of the reefs. Their densities varied from 0 to 238 ind./dm², with an average of 34 ± 68 ind./dm². If we account for dead individuals (empty barnacle plates), they correspond to 25.9% of the sampled population. The presence of oil possibly affected barnacle survival rates but did not seem to prevent barnacle individuals from reaching adult sizes. We also found individuals of the snail Echinolittorina lineolata (d'Orbigny, 1840) crawling on these barnacles, indicating that the barnacle assemblages on oil stains are stable enough to provide refuge for these snails. It is not clear if the presence of barnacles on oil reflects the resistance of these crustaceans to the oil toxicity or is just a result of a low substrate selectivity by the cypris larvae.

自 2019 年 8 月以来，巴西东北部海岸发生了超过 3000 公里的大规模漏油事件。此次漏油的原因和起源仍然是个谜，对沿海生态系统的影响迄今尚未明确。尽管努力去除油污（主要来自当地社区），但海滩、红树林和海滩岩石中仍然存在油渍。在这份简短的报告中，我们描述了藤壶Chthamalus bisinuatus的发生Pilsbry，1916 年，在第一次石油记录一年后，在海滩岩石的潮间带表面上定植溢油污渍。我们快速评估了位于巴伊亚（巴西东北部）孔德市的三个不同珊瑚礁的油渍，在那里确定了该物种并计算了其在油渍上的密度。油渍中藤壶的出现仅限于珊瑚礁之后的区域。它们的密度从 0 到 238 ind./dm ²不等，平均为 34 ± 68 ind./dm ²。如果我们考虑死亡个体（空藤壶板），则它们对应于抽样人口的 25.9%。石油的存在可能会影响藤壶的存活率，但似乎并没有阻止藤壶个体达到成年尺寸。我们还发现了蜗牛的个体Echinolittorina lineolata (d'Orbigny, 1840) 在这些藤壶上爬行，表明油渍上的藤壶组合足够稳定，可以为这些蜗牛提供避难所。目前尚不清楚油上藤壶的存在是否反映了这些甲壳类动物对油毒性的抵抗力，或者仅仅是由于鲤鱼幼虫对底物的选择性低。