In recent decades, the management of urban surface runoff in coastal regions has become a global priority. However, in Brazil, whose coastline is 8,500 km, these actions are still scarce. This study aimed to characterise, for the first time, the structure of the benthic assemblages near urban drainage channels, whose waters flow permanently to four beaches of Guarujá, São Paulo, Brazil. Collection of sediments took place between October 2017 and August 2018. Macroinvertebrate fauna were identified in a certified laboratory using international standard methodologies. The data showed that although the species richness was in general low, a great abundance and density of taxa tolerant to organic pollution was observed (e.g. Oligochaeta, Gastropoda and, mainly Insecta: Ceratopogonidae, Chironomidae, Chironomus and Culicidae) during the period of greatest tourist influx (rainy season/summer). Furthermore, the results of water quality indexes (in all channels) suggested heavily polluted environments: (i) Shannon-Wiener: H’ < 1; (ii) Biological Monitoring Working Party: BMWP’ < 12 and (iii) Average Score per Taxon: ASPT < 2. Therefore, it is urgent to adopt management measures to improve the environmental water quality and to prevent human health risks associated with tourism activities taking place in the recreational coastal waters of Guarujá municipality.

近几十年来，沿海地区城市地表径流的管理已成为全球重点工作。但是，在海岸线长达8500公里的巴西，这些行动仍然很少。这项研究的目的是首次表征城市排水渠附近的底栖组合的结构，这些排水源的水永久流向巴西圣保罗的瓜鲁加四个海滩。沉积物的收集在2017年10月至2018年8月之间进行。大型无脊椎动物区系在采用国际标准方法的认证实验室中进行了鉴定。数据显示，尽管物种丰富度普遍较低，但观察到耐有机污染的分类单元的丰度和密度很高（例如，Oligochaeta，Gastropoda和主要是Insecta：Ceratopogonidae，Chironomidae，Chironomus和蜂科）在游客人数最多的时期（雨季/夏季）。此外，水质指数（在所有渠道中）的结果都表明环境严重污染：（i）Shannon-Wiener：H' <1；（ii）生物监测工作组：BMWP'<12，以及（iii）每类分类的平均分数：ASPT <2。因此，迫切需要采取管理措施来改善环境水质并防止与旅游活动有关的人类健康风险发生在瓜鲁雅自治市的休闲沿海水域。