Green turtle movements in the Gulf of Mexico: Tracking reveals new migration corridor and habitat use suggestive of MPA expansion

Lamont, Margaret M.; Benscoter, Allison M.; Hart, Kristen M.

doi:10.1016/j.gecco.2023.e02380

Cited by 3 publications

(1 citation statement)

References 65 publications

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“…Pillans et al., 2021; Whiting & Miller, 1998), Argos tracking (e.g. Attum et al., 2014; Broderick et al., 2007; Fujisaki et al., 2016; Hart et al., 2017; Lamont et al., 2023; Naro‐Maciel et al., 2018; Ng et al., 2018; Rees et al., 2013; Sloan et al., 2022; Uribe‐Martínez et al., 2021) and Fastloc GPS techniques (e.g. Gredzens et al., 2014; Shimada, Jones, Limpus, Groom, et al., 2016).…”

Section: Resultsmentioning

confidence: 99%

Individual variation in home‐range across an ocean basin and links to habitat quality and management

Hays,

Rattray,

Shimada

et al. 2024

Journal of Applied Ecology

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Overgrazing may lead to management intervention (e.g. culling, animal relocation) to try and prevent habitat destruction. Overgrazing leading to seagrass meadow collapse has been recorded for green turtles (Chelonia mydas) at several sites around the world, although the generality of this phenomenon and the need for intervention to prevent widespread seagrass destruction is unknown. Where turtles have degraded seagrass meadows, home‐ranges are expected to be large and turtles will relocate as meadows are destroyed. We used high resolution Fastloc GPS tracking (n = 32 individuals, mean = 171 days per individual, SD = 99) to record the home‐range of adult green turtles at foraging sites spanning 4523 km of longitude across the Western Indian Ocean. Contrary to predictions if overgrazing was occurring, we recorded small home‐ranges and turtles rarely relocated their daytime foraging areas. Based on all locations received, the mean 50% and 95% utilisation distributions (UD50 and UD95) were 2.4 km2 (SD = 2.7) and 15.4 km2 (SD = 17.7). Space use was often particularly small at night, when turtles rest, averaging 11% of the overall space use with the mean night‐time UD50 and UD95 being 0.15 km2 (SD = 0.1) and 1.1 km2 (SD = 0.8), respectively. Variation in home‐range across individuals was not influenced by the data volume (number of locations per day, duration of tracking) or animal size (carapace length) but increased significantly as the distance between the centre of day and night areas increased, that is individuals that had a larger daily commute had the larger home‐ranges. Synthesis and applications. Comparisons with home‐range estimates from 16 previous studies, showed that those we recorded are among the smallest for adult green turtles globally. These results suggest that despite population size increases at several major nesting sites in the Western Indian Ocean, green turtles are generally not destroying the seagrass meadows on which they forage and so management intervention to prevent overgrazing is not needed. In this way, our work illustrates how movement data may inform management decisions for green turtles. Further targeted work on the seagrass ecosystem health could help confirm this suggestion.

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Section: Resultsmentioning

confidence: 99%

Individual variation in home‐range across an ocean basin and links to habitat quality and management

Hays,

Rattray,

Shimada

et al. 2024

Journal of Applied Ecology

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Regional foraging areas of green turtles (Chelonia mydas) nesting at Aldabra Atoll: insights from stable isotopes and satellite telemetry

Sanchez,

Casale,

Bunbury

et al. 2024

Biodivers Conserv

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Sea turtles spend the majority of their lives at foraging grounds. These areas are important for population persistence but generally occur in coastal habitats, which are under increasing human pressure. Identifying key foraging areas is therefore an important step to understanding critical sea turtle habitats, and therefore their threats. Isotope ratios (δ15N, δ13C) from skin tissues of 90 green turtles (Chelonia mydas) nesting at the regionally important rookery of Aldabra Atoll, Seychelles, were analyzed with samples collected during two periods: 51 samples from March to September 2021, and 39 samples from January to April 2022. These analyses were complemented by nine satellite tracks to identify key foraging areas. Hierarchical clustering and discriminant function analysis identified two main foraging areas: the East African coast (Tanzania and Somalia) and northern Madagascar. Isotopic values indicated that the majority of green turtles nesting at Aldabra forage at one of these two areas, with slightly more green turtles visiting the East African coast. Geographical isotopic patterns were not found latitudinally, suggesting a potential limit to this approach for coastal areas in the Western Indian Ocean. However, we found longitudinal variation of δ13C and δ15N that few studies have reported. This is the first study in this region to combine satellite telemetry and stable isotope analysis to assign likely foraging areas of green turtles and advances understanding of the complex migration patterns and foraging ecology of this species. We demonstrate the potential and the limitations of stable isotope analysis for identifying/characterizing green turtle foraging areas in this region.

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Satellite telemetry reveals high-use internesting areas and international foraging extent for loggerhead turtles tagged in southeast Florida, USA

Goodwin,

Hart,

Evans

et al. 2024

Endang. Species. Res.

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Developing conservation strategies for highly migratory marine species relies on understanding their spatial distributions. Nesting populations of female loggerhead (Caretta caretta) turtles typically travel from widely dispersed foraging areas and make use of common internesting areas between nesting events. Protection of these areas is essential to the conservation of this species. In this study, we used satellite tracking and behavioral switching state-space movement modeling to examine the internesting use-areas, migration patterns, and foraging area distribution of a previously uninvestigated nesting loggerhead population in southeast Florida. While these turtles spent much of their internesting period close to their nesting site, only 17.4% of the identified internesting area is within the boundaries currently designated under the US Endangered Species Act as critical loggerhead ‘nearshore reproductive habitat’. Additionally, 72% of turtles in this study (17 of 21) that were tracked to foraging grounds have foraging home ranges outside of the USA, with 62% of turtles (n = 13) in The Bahamas. Considering the proximity of their internesting areas to a large human population center and their largely international foraging distribution, this population could benefit from expanding federally designated critical habitat, along with developing collaborative conservation strategies between the USA and The Bahamas.

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Green turtle movements in the Gulf of Mexico: Tracking reveals new migration corridor and habitat use suggestive of MPA expansion

Cited by 3 publications

References 65 publications

Individual variation in home‐range across an ocean basin and links to habitat quality and management

Individual variation in home‐range across an ocean basin and links to habitat quality and management

Regional foraging areas of green turtles (Chelonia mydas) nesting at Aldabra Atoll: insights from stable isotopes and satellite telemetry

Satellite telemetry reveals high-use internesting areas and international foraging extent for loggerhead turtles tagged in southeast Florida, USA

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