NoteMarine debris ingestion by coastal dolphins: What drives differences between sympatric species?

•Sympatric coastal dolphins interact in different way with marine debris.•Differences in feeding activities are driven differences in marine debris ingestion.•Pontoporia blainvillei feeds near bottom and is more vulnerable to debris ingestion.•Sotalia guianensis feeds near surface and its interaction with debris is reduced.•Seabed is the main source of debris to the coastal dolphins.

This study compared marine debris ingestion of the coastal dolphins Pontoporia blainvillei and Sotalia guianensis in a sympatric area in Atlantic Ocean. Among the 89 stomach contents samples of P. blainvillei, 14 (15.7%) contained marine debris. For S. guianensis, 77 stomach contents samples were analyzed and only one of which (1.30%) contained marine debris. The debris recovered was plastic material: nylon yarns and flexible plastics. Differences in feeding habits between the coastal dolphins were found to drive their differences regarding marine debris ingestion. The feeding activity of P. blainvillei is mainly near the sea bottom, which increases its chances of ingesting debris deposited on the seabed. In contrast, S. guianensis has a near-surface feeding habit. In the study area, the seabed is the main zone of accumulation of debris, and species with some degree of association with the sea bottom may be local bioindicators of marine debris pollution.