Resting Dynamics and Diel Activity of the Green Turtle (Chelonia mydas) in Rapa Nui, Chile

Petit, Ignacio J.; González, Camila F.; Gusmao, Joao B.; Álvarez-Varas, Rocío; Hinojosa, Iván A.

doi:10.2744/ccb-1374.1

Cited by 11 publications

(9 citation statements)

References 38 publications

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“…For example, the trajectory of ascent phases became increasingly directional on high, flood tides, to potentially exploit the vast intertidal areas of Yawuru Nagulagun Roebuck Bay that become accessible on these tides [71,144]. This is similar to other species of sea turtle that use high tides to access foraging habitat such as mangroves [145] or feed on benthic prey as they emerge upon inundation in the intertidal [114,146]. Conversely, we found similar effects for both ebb and flood tides on the behaviour of turtles during bottom and ascent phases of dives, suggesting that behaviour is somewhat similar between rising and falling tides.…”

Section: Discussionmentioning

confidence: 99%

Multivariate analysis of biologging data reveals the environmental determinants of diving behaviour in a marine reptile

Hounslow

Fossette²,

Byrnes

et al. 2022

R. Soc. open sci.

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Diving behaviour of ‘surfacers' such as sea snakes, cetaceans and turtles is complex and multi-dimensional, thus may be better captured by multi-sensor biologging data. However, analysing these large multi-faceted datasets remains challenging, though a high priority. We used high-resolution multi-sensor biologging data to provide the first detailed description of the environmental influences on flatback turtle ( Natator depressus ) diving behaviour, during its foraging life-history stage. We developed an analytical method to investigate seasonal, diel and tidal effects on diving behaviour for 24 adult flatback turtles tagged with biologgers. We extracted 16 dive variables associated with three-dimensional and kinematic characteristics for 4128 dives. K -means and hierarchical cluster analyses failed to identify distinct dive types. Instead, principal component analysis objectively condensed the dive variables, removing collinearity and highlighting the main features of diving behaviour. Generalized additive mixed models of the main principal components identified significant seasonal, diel and tidal effects on flatback turtle diving behaviour. Flatback turtles altered their diving behaviour in response to extreme tidal and water temperature ranges, displaying thermoregulation and predator avoidance strategies while likely optimizing foraging in this challenging environment. This study demonstrates an alternative statistical technique for objectively interpreting diving behaviour from multivariate collinear data derived from biologgers.

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Section: Discussionmentioning

confidence: 99%

Multivariate analysis of biologging data reveals the environmental determinants of diving behaviour in a marine reptile

Hounslow

Fossette²,

Byrnes

et al. 2022

R. Soc. open sci.

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“…Our findings highlight the relevance of establishing local actions aiming to decrease the impact caused by high artisanal-boat traffic in sea turtle feeding and resting areas in Easter Island. Reduction of boat speed limits in specific areas of the bay and requiring the use of propeller protectors are some actions recommended to decrease the number of fatal encounters between boats and turtles in the island [ 68 ].…”

Section: Discussionmentioning

confidence: 99%

Genetics, Morphometrics and Health Characterization of Green Turtle Foraging Grounds in Mainland and Insular Chile

Álvarez-Varas

Medrano²,

Benítez

et al. 2022

Animals

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Two divergent genetic lineages have been described for the endangered green turtle in the Pacific Ocean, occurring sympatrically in some foraging grounds. Chile has seven known green turtle foraging grounds, hosting mainly juveniles of different lineages. Unfortunately, anthropic factors have led to the decline or disappearance of most foraging aggregations. We investigated age-class/sex structure, morphological variation, genetic diversity and structure, and health status of turtles from two mainland (Bahia Salado and Playa Chinchorro) and one insular (Easter Island) Chilean foraging grounds. Bahia Salado is composed of juveniles, and with Playa Chinchorro, exclusively harbors individuals of the north-central/eastern Pacific lineage, with Galapagos as the major genetic contributor. Conversely, Easter Island hosts juveniles and adults from both the eastern Pacific and French Polynesia. Morphological variation was found between lineages and foraging grounds, suggesting an underlying genetic component but also an environmental influence. Turtles from Easter Island, unlike Bahia Salado, exhibited injuries/alterations probably related to anthropic threats. Our findings point to establishing legal protection for mainland Chile’s foraging grounds, and to ensure that the administrative plan for Easter Island’s marine protected area maintains ecosystem health, turtle population viability, and related cultural and touristic activities.

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“…Similarly, temperature and rainfall patterns dictate growth and senescence of primary producers [25,26], which are a key diet item for green turtles at non-reef neritic foraging grounds [7,[27][28][29][30]. Green turtle activity cycles [31,32], physiology [33][34][35] and orientation [36] are often linked to the diurnal cycle, and tides provide intermittent access to intertidal habitat and can facilitate passive transport of foraging green turtles [1][2][3]21,36]. Despite these probable interactions little is known about how daily or seasonal changes in microhabitats in uence patterns of movement or residency.…”

Section: Introductionmentioning

confidence: 99%

Should I stay or should I go? The influence of environmental conditions on green turtle residence time and outward transit in foraging areas

Webster,

Duce,

Hamann

et al. 2023

Preprint

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Foraging animals move through the environment to satisfy their requirements for food, rest, reproduction and risk-avoidance. Understanding how animals respond to changing environmental conditions can help to characterise favourable habitat and determine whether they might be motivated to depart when those habitats become unsuitable. Foraging green turtles are typically residents that scarcely move in response to environmental changes or disturbances. Some individuals though, exhibit high mobility. We developed an analysis of Fastloc GPS tracks of 61 green turtles using cox regression models and generalised linear mixed models to investigate the influence of a suite of environmental characteristics on the length of residence time and probability of turtles transitioning between two behavioural modes, “stay” or “go”. Decisions to move (“go”) were influenced by short-term changes in the local environmental conditions. Individuals were more likely to “stay” when temperature increased during their stay and were more likely to “go” when turbidity decreased, and they entered deeper habitats. This result implies that foraging and resting (“staying”) primarily occurs in benthic, shallow, warm habitats, while travel (“going”) is facilitated in deeper, clear water. We also determined that individuals within the green turtle foraging aggregation respond differently to environmental cues to move and hypothesise that a diversity of strategies within a foraging aggregation could confer its resilience to disturbance events. Our study provides new evidence of the factors influencing movements in green turtles and can aid in predicting how they may respond to future changes and enhance risk mitigation efforts through dynamic and adaptive planning.

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Resting Dynamics and Diel Activity of the Green Turtle (Chelonia mydas) in Rapa Nui, Chile

Cited by 11 publications

References 38 publications

Multivariate analysis of biologging data reveals the environmental determinants of diving behaviour in a marine reptile

Multivariate analysis of biologging data reveals the environmental determinants of diving behaviour in a marine reptile

Genetics, Morphometrics and Health Characterization of Green Turtle Foraging Grounds in Mainland and Insular Chile

Should I stay or should I go? The influence of environmental conditions on green turtle residence time and outward transit in foraging areas

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