Understanding the population composition and dynamics of migratory megafauna at key developmental habitats is critical for conservation and management. The present study investigated whether diferential recovery of Caribbean green turtle (Chelonia mydas) rookeries infuenced population composition at a major juvenile feeding ground in the southern Caribbean (Lac Bay, Bonaire, Caribbean Netherlands) using genetic and demographic analyses. Genetic divergence indicated a strong temporal shift in population composition between 2006–2007 and 2015–2016 (φST=0.101, P<0.001). Juvenile recruitment (<75.0cm straight carapace length; SCL) from the north-western Caribbean increased from 12% to 38% while recruitment from the eastern Caribbean region decreased from 46% to 20% between 2006–2007 and 2015–2016. Furthermore, the product of the population growth rate and adult female abundance was a signifcant predictor for population composition in 2015–2016. Our results may refect early warning signals of declining reproductive output at eastern Caribbean rookeries, potential displacement efects of smaller rookeries by larger rookeries, and advocate for genetic monitoring as a useful method for monitoring trends in juvenile megafauna. Furthermore, these fndings underline the need for adequate conservation of juvenile developmental habitats and a deeper understanding of the interactions between megafaunal population dynamics in diferent habitats.
Referenced in BioNews 31 article "Genetic Testing to Measure Sea Turtle Conservation Success"