Abstract
BackgroundA strong behavioural plasticity is commonly evidenced in the movements of marine megafauna species, and it might be related to an adaptation to local conditions of the habitat. One way to investigate such behavioural plasticity is to satellite track a large number of individuals from contrasting foraging grounds, but despite recent advances in satellite telemetry techniques, such studies are still very limited in sea turtles.MethodsFrom 2010 to 2018, 49 juvenile green turtles were satellite tracked from five contrasting feeding grounds located in the South-West Indian Ocean in order to (1) assess the diel patterns in their movements, (2) investigate the inter-individual and inter-site variability, and (3) explore the drivers of their daily movements using both static (habitat type and bathymetry) and dynamic variables (daily and tidal cycles).ResultsDespite similarities observed in four feeding grounds (a diel pattern with a decreased distance to shore and smaller home ranges at night), contrasted habitats (e.g. mangrove, reef flat, fore-reef, terrace) associated with different resources (coral, seagrass, algae) were used in each island.ConclusionsJuvenile green turtles in the South-West Indian Ocean show different responses to contrasting environmental conditions - both natural (habitat type and tidal cycle) and anthropogenic (urbanised vs. uninhabited island) demonstrating the ability to adapt to modification of habitat.
Highlights
A strong behavioural plasticity is commonly evidenced in the movements of marine megafauna species, and it might be related to an adaptation to local conditions of the habitat
Diel migrations in the marine realm have been documented in a large range of marine species, from plankton [8, 9], seals [10, 11], cetaceans [12, 13], fish [14] to sea turtles [15,16,17,18,19]. Using satellite telemetry, such day-night differences have been recently observed in sea turtles
General tracking data After filtering, a total of 49 juvenile green turtles were satellite tracked in Europa (n = 11), Glorieuses (n = 10), Juan de Nova (n = 9), Mayotte (n = 9) and La Reunion (n = 10), representing a large dataset of 20,277 Global Positioning System (GPS)
Summary
A strong behavioural plasticity is commonly evidenced in the movements of marine megafauna species, and it might be related to an adaptation to local conditions of the habitat. One way to investigate such behavioural plasticity is to satellite track a large number of individuals from contrasting foraging grounds, but despite recent advances in satellite telemetry techniques, such studies are still very limited in sea turtles During their life, animals spend a considerable amount of time on the move [1]. Courbin et al [7] have shown that zebras exhibit a diel migration strategy associated with a particular habitat (vegetation cover at night) to adjust their behaviour to lions’ presence, and. Using satellite telemetry, such day-night differences have been recently observed in sea turtles. Given that sea turtles rely on visual cues to forage and detect predators [22], this (2020) 8:1 nocturnal behaviour is likely associated with resting and/or a predator avoidance strategy, whereas larger home ranges with higher activity levels during day-time may correspond to a foraging activity [15, 23, 24]
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