Meeting Abstract
Interannual, sometime cyclic, variation in numbers of sea turtles nesting on beaches complicates estimates of both population sizes and trends and can affect population dynamics. We update and extend an earlier, probabilistic, physiologically-based model of the effects of variation in ocean temperature and resources on intervals between sea turtle nesting migrations. As with earlier models, simulations suggest that variation in temperature (and induced variation in resource acquisition) might induce variation in sea turtle remigration but is unlikely to create sustained cycles in migration. Additional results from the refined model include: 1) predicted immediate responses to pulses of increased/decreased resources depends both on the magnitude of the resource pulse and on recent resource levels, 2) time to return to a baseline depends primarily on historical and ongoing resource levels, 3) lower resource levels result in prolonged ‘ringing’ of the migration response around a baseline and increased ability to support short term cycling of remigration. Hence lower resource levels would be expected to result in short term cyclicity of migration rates. Attempts to match predicted variation in migration rates due to historical temperature variation at several leatherback nesting beaches were complicated by substantial local and regional variation in responses of resources (estimated by net primary productivity) to variation in sea surface temperature.
