Influence of oxygenation and quality of sediment on the survival of Scolelepis chilensis (Spionidae: Polychaeta) in Guanabara Bay, Rio de Janeiro

This study aimed to evaluate the tolerance of the polychaete Scolelepis chilensis to variation in oxygenation and sediment to obtain data for environmental impact studies. Individuals were collected at Flamengo Beach, Rio de Janeiro. Favorable combinations of environmental characteristics of Guanabara Bay explain the survival of the organisms, although the introduction of pollutants produces heavily degraded areas. Among the groups of benthic fauna, polychaetes especially play an important role in the functioning and structure of aquatic communities. Scolelepis chilensis is widely distributed due to its morphological characteristics, which allow it to adapt to diverse marine environments. However, this study showed that this polychaete has a high mortality rate under hypoxic conditions, meaning that this species is more sensitive to environments with low oxygen. Furthermore, the mortality rate increases considerably in situations of hypoxia associated with contaminated sediment, indicating that this species is sensitive to environments with contaminated sediment and low oxygen supply. Thus, the intense and continuous input of pollutants could lead to a future deficit of oxygen and extreme anaerobic conditions, which may cause destruction of various marine ecosystems.