Ph.D. Hinojosa-Toledo, Ivan

Understanding animals' daily activity patterns such as foraging and resting is key to the effective conservation of individuals, populations, and species. Expanding habitat usage by humans today is likely one of the major factors influencing animal habitat use and behavior. Rapa Nui, a remote Chilean island located at the easternmost corner of the Polynesian Triangle, hosts a population of green turtles, Chelonia mydas, that have been monitored by citizen scientists since 2010. Through the collaborative work of divers from the local community and professional scientists, we describe C. mydas daily underwater resting and foraging patterns in Rapa Nui. We identified 15 individuals by monitoring 19 specific resting locations within the Rapa Nui coral reef. A high level of spatial fidelity for specific resting sites was observed in 12 turtles that used the same location for as long as 5 yrs. Moreover, we observed a clear temporal pattern in the daily use of resting habitats, with 79% of resting activity occurring during low tide. In contrast, the daily peak in feeding activity was associated with high tides. Abiotic characteristics (depth and cardinal orientation) of resting sites did not show significant relationships. The information from this study will inform management of the Rapa Nui Multiple Uses Coastal Marine Protected Area to increase the protection of marine turtles residing at this isolated Pacific Island.

Anthropogenic Marine Debris (AMD) in the SE Pacific has primarily local origins from land-based sources, including cities (coastal and inland), beach-goers, aquaculture, and fisheries. The low frequency of AMD colonized by oceanic biota (bryozoans, lepadid barnacles) suggests that most litter items from coastal waters of the Humboldt Current System (HCS) are pulled offshore into the South Pacific Subtropical Gyre (SPSG). The highest densities of floating micro- and macroplastics are reported from the SPSG. An extensive survey of photographic records, unpublished data, conference proceedings, and published studies revealed interactions with plastics for 97 species in the SE Pacific, including 20 species of fish, 5 sea turtles, 53 seabirds, and 19 marine mammals. Sea turtles are most affected by interactions with plastics, underlined by the fact that 4 of the 5 species suffer both from entanglement and ingestion. Reports gathered in this review suggest that interactions along the continental coast are mostly via entanglement. High frequencies of microplastic ingestion have been reported from planktivorous fish and seabirds inhabiting the oceanic waters and islands exposed to high densities of microplastics concentrated by oceanic currents in the SPSG. Our review also suggests that some species from the highly productive HCS face the risk of negative interactions with AMD, because food and plastic litter are concentrated in coastal front systems. In order to improve the conservation of marine vertebrates, especially of sea turtles, urgent measures of plastic reduction are needed.