One Shell of a Problem: Cumulative Threat Analysis of Male Sea Turtles Indicates High Anthropogenic Threat for Migratory Individuals and Gulf of Mexico Residents

• Published in: Remote sensing (Basel, Switzerland) Vol. 14; no. 16; p. 3887
• Main Authors: Ashford, Micah, Watling, James I., Hart, Kristen
• Format: Journal Article
• Language: English
• Published: Basel MDPI AG 01-08-2022
• Subjects: 21st century; Anthropogenic factors; Aquatic reptiles; Breeding sites; Caretta caretta; Chelonia mydas; conservation; Corridors; COVID-19; cumulative threat; Dermochelys coriacea; Eretmochelys imbricata; Exposure; Fish; Fisheries; Foraging behavior; Lepidochelys kempii; Lepidochelys olivacea; Light pollution; Light sources; Males; Marine environment; Marine protected areas; Natator depressus; National parks; Oceans; Oil pollution; PCB; Polychlorinated biphenyls; Protected areas; sea turtle; Sea turtles; State space models; Threat evaluation; Threats; Tourism; Wildlife sanctuaries; Florida Keys; Greece; Mexico; Dry Tortugas; Gulf of Mexico; United States > US
• ISSN: 2072-4292; 2072-4292
• DOI: 10.3390/rs14163887

Human use of oceans has dramatically increased in the 21st century. Sea turtles are vulnerable to anthropogenic stressors in the marine environment because of lengthy migrations between foraging and breeding sites, often along coastal migration corridors. Little is known about how movement and threat interact specifically for male sea turtles. To better understand male sea turtle movement and the threats they encounter, we satellite-tagged 40 adult male sea turtles of four different species. We calculated movement patterns using state-space modeling (SSM), and quantified threats in seven unique categories; shipping, fishing, light pollution, oil rigs, proximity to coast, marine protected area (MPA) status, and location within or outside of the U.S. Exclusive Economic Zone (EEZ). We found significantly higher threat severity in northern and southern latitudes for green turtles (Chelonia mydas) and Kemp’s ridleys (Lepidochelys kempii) in our study area. Those threats were pervasive, with only 35.9% of SSM points encountering no high threat exposure, of which 47% belong to just two individuals. Kemp’s ridleys were most exposed to high threats among tested species. Lastly, turtles within MPA boundaries face significantly lower threat exposure, indicating MPAs could be a useful conservation tool.