6 research outputs found
Somatic growth dynamics of West Atlantic hawksbill sea turtles: a spatio-temporal perspective
This is the final version of the article. Available from the publisher via the DOI in this record.Somatic growth dynamics are an integrated response to environmental conditions. Hawksbill
sea turtles (Eretmochelys imbricata) are long-lived, major consumers in coral reef habitats that move over
broad geographic areas (hundreds to thousands of kilometers). We evaluated spatio-temporal effects on
hawksbill growth dynamics over a 33-yr period and 24 study sites throughout the West Atlantic and explored
relationships between growth dynamics and climate indices. We compiled the largest ever data set
on somatic growth rates for hawksbills – 3541 growth increments from 1980 to 2013. Using generalized additive
mixed model analyses, we evaluated 10 covariates, including spatial and temporal variation, that could
affect growth rates. Growth rates throughout the region responded similarly over space and time. The lack
of a spatial effect or spatio-temporal interaction and the very strong temporal effect reveal that growth rates
in West Atlantic hawksbills are likely driven by region-wide forces. Between 1997 and 2013, mean growth
rates declined significantly and steadily by 18%. Regional climate indices have significant relationships with
annual growth rates with 0- or 1-yr lags: positive with the Multivariate El Niño Southern Oscillation Index
(correlation = 0.99) and negative with Caribbean sea surface temperature (correlation = −0.85). Declines
in growth rates between 1997 and 2013 throughout the West Atlantic most likely resulted from warming
waters through indirect negative effects on foraging resources of hawksbills. These climatic influences are
complex. With increasing temperatures, trajectories of decline of coral cover and availability in reef habitats
of major prey species of hawksbills are not parallel. Knowledge of how choice of foraging habitats, prey
selection, and prey abundance are affected by warming water temperatures is needed to understand how
climate change will affect productivity of consumers that live in association with coral reefs