Cumulative threats to juvenile green turtles in the coastal waters of southern and southeastern Brazil

Abstract

Management of marine turtles at broad spatial scales is challenging due to the costs and the logistical feasibility of collecting ecological data and information on multiple threats at this scale. Spatially explicit assessments of the exposure of marine turtles to cumulative threats provides an alternative approach by identifying regions that are impacted by multiple threats at broad scales. To inform future management of juvenile green turtles, Chelonia mydas, off the southern and southeastern Brazilian coast we determined their cumulative exposure to five pertinent anthropogenic activities (marine traffic, port areas, and artisanal, trawl and gillnet fisheries). Information on the spatial distribution of juvenile green turtles was obtained by satellite tagging 14 wild-caught turtles in the Paranagua Estuarine Complex, off the Parana coast in southern Brazil and human activity information was obtained from various databases. This allowed us to identify the anthropogenic activities that provide the greatest risk to marine turtles (artisanal fisheries and marine traffic) and five “hotspot” threat areas that require prompt local management intervention to protect marine turtles in the region. These results can be used to inform on the ground efforts where further impact assessments and management interventions can be prioritized and undertaken.