Origins of juvenile green sea turtles (Chelonia mydas) in the Bahamas: A comparison of recent and historical rookery contributions

Abstract

Conservation of green sea turtles ( Chelonia mydas ) benefits from knowledge of population connectivity across life stages. Green turtles are managed at the level of genetically discrete rookeries, yet individuals from different rookeries mix at foraging grounds; therefore, rookeries may be impacted by processes at foraging grounds. Bimini, Bahamas, hosts an important foraging assemblage, but rookery contributions to this assemblage have never been resolved. We generated mitochondrial DNA sequences for 96 foraging green turtles from Bimini and used Mixed Stock Analysis to determine rookery contributions to this population using 817 and 490 base pair (bp) rookery baseline data. The MSA conducted with 817 bp data indicated that Quintana Roo, Mexico, and Central Eastern Florida contributed most to the Bimini population. The MSA conducted with 490 bp data indicated that Southwest Cuba and Central Eastern Florida contributed the most to Bimini. The results of the second MSA differ from a previous study undertaken with 490 bp data, conducted in Great Inagua, Bahamas, which suggested that Tortuguero, Costa Rica, contributed the most to that foraging assemblage. Large credible intervals in our results do not permit explicit interpretation of individual rookery contributions, but our results do indicate substantial relative differences in rookery contributions to two Bahamian foraging assemblages which may be driven by oceanic currents, rookery sizes, and possibly juvenile natal homing. Our findings may implicate a shift in contributions to the Bahamas over two decades, highlighting the importance of regularly monitoring rookery contributions and resolving regional recruitment patterns to inform conservation.

Mixed stock analysis identifies natal origins of green turtles at foraging grounds in southeastern Australia

“…MSA can also contribute to our understanding of the impact of climate change on green turtles (Jensen et al, 2018). A combination of factors, including ocean current patterns, geographic distance, and relative genetic stock size have been found to significantly influence the composition of green turtle foraging grounds (Lahanas et al, 1998;Jensen et al, 2020;Kynoch et al, 2022;Stahelin et al, 2022). Findings of foraging turtles that originate from distant rookeries (Naro-Maciel et al, 2014;Read et al, 2015;Jones et al, 2018) and size class segregation at different foraging grounds (Hamabata et al, 2018) indicate that additional drivers, such as active swimming, geomagnetic imprinting and environmental conditions, may influence foraging habitat selection by juveniles (Lohmann et al, 2008;Naro-Maciel et al, 2014;Read et al, 2014;Putman and Mansfield, 2015).…”