Selectivity of marine-debris ingestion by juvenile green turtles (Chelonia mydas) at a South American World Heritage Listed area

Beaches in southern Brazil have substantial marine debris and strandings of dead juvenile green turtles (Chelonia mydas). This study investigates associations by quantifying marine debris (1) ingested among new (<40 cm curved carapace length; CCL) and older (>40 cm CCL) juvenile C. mydas recruits; (2) concentrations on beach transects; and then (3) selective ingestion by C. mydas. Among 40 C. mydas (2014-2015), 93% had ingested debris, with smaller individuals having proportionally more. Sheet-like and hard plastics were the most frequently ingested, and commonly concentrated on beach transects. Estuarine beach transects had more debris than those facing the ocean. Selectivity analyses revealed all C. mydas avoided white miscellaneous debris and straws, while smaller conspecifics selected clear sheet-like plastics and avoided coloured ones. The results reiterate a need for long-term reforms to regional waste disposal and short-term initiatives encouraging social awareness to avoid key plastics and reduce ingestion by C. mydas.

Automated summary

Beaches in southern Brazil are facing issues of substantial marine debris and strandings of dead juvenile green turtles. This study found that 93% of the sampled turtles had ingested debris, with smaller individuals ingesting proportionally more. The type and concentration of marine debris varied on different beach transects, with turtles showing selectivity in their ingestion patterns.