Ontogenetic diet shifts of green sea turtles (Chelonia mydas) in a mid-ocean developmental habitat

Burgett, Claire M.; Burkholder, Derek A.; Coates, Kathryn A.; Fourqurean, Virginia; Kenworthy, W. J.; Manuel, Sarah A.; Outerbridge, Mark E.; Fourqurean, James W.

doi:10.1007/s00227-018-3290-6

Cited by 41 publications

(24 citation statements)

References 58 publications

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“…However, when threat data were presented for the species associated with these habitats, 52% of the IUCN species assessments did not mention any form of human-induced habitat change. The effects of habitat change can be overlooked for marine animals [45] because of the sub-lethal, chronic effects that occur initially, and because impacts can be hard to directly attribute to species declines without long-term datasets separating natural fluctuations from the effects of human impacts [46]. This is particularly true for sharks and rays, the largest group of species without habitat change listed as a threat.…”

Section: Bringing Habitat Loss and Degradation In Vegetated Coastal Wmentioning

confidence: 99%

“…This is especially true for the persistence of harvested megafauna (i.e. fisheries species) with critical life history links to threatened habitats, because under this scenario, fishery management alone may be insufficient to prevent population declines [45]. In this case, incorporating habitat change into conservation assessments and management plans could be achieved by recognizing the importance of vegetated coastal wetlands to marine megafauna and conducting robust research into the habitat associations that exist.…”

Section: Bringing Habitat Loss and Degradation In Vegetated Coastal Wmentioning

confidence: 99%

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The Role of Vegetated Coastal Wetlands for Marine Megafauna Conservation

Sievers

Brown

Tulloch

et al. 2019

Trends in Ecology & Evolution

123

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Section: Bringing Habitat Loss and Degradation In Vegetated Coastal Wmentioning

confidence: 99%

Section: Bringing Habitat Loss and Degradation In Vegetated Coastal Wmentioning

confidence: 99%

The Role of Vegetated Coastal Wetlands for Marine Megafauna Conservation

Sievers

Brown

Tulloch

et al. 2019

Trends in Ecology & Evolution

123

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“…Ontogenetic dietary change is complex and varies regionally (e.g., Cardona et al 2010;Fukuoka et al 2019). Typically, the diet is omnivorous during the early pelagic stages and becomes primarily herbivorous after recruitment to the neritic zone (e.g., Howell et al 2016;Vélez-Rubio et al 2016;Burgett et al 2018). In the Central North Pacific, however, some individuals up to 70 cm curved carapace length (CCL) forage pelagically on a primarily carnivorous diet (Parker et al 2011).…”

Section: Introductionmentioning

confidence: 99%

Green turtle diet is dominated by seagrass in the Western Indian Ocean except amongst gravid females

et al. 2019

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Green turtles (Chelonia mydas) are key herbivores of tropical and subtropical neritic habitats and play a major role in structuring seagrass meadows. We present the first detailed assessment of green turtle diet in the Western Indian Ocean using the gut contents of salvaged animals from three atolls in the Republic of Seychelles separated from each other by 400-825 km: Cosmoledo (adults, n = 12), Farquhar (adults, n = 33; immature, n = 1) collected in 1982-1983; and Desroches (immatures, n = 8) in 2016-2018. We report the first comparison of the diets of gravid females (n = 17), males (n = 26) and non-breeding females (n = 2) at sites providing both foraging and breeding habitat. Seagrass (mostly Thalassodendron ciliatum) dominated the diet, accounting for 95% of the mean gut content biomass for males and non-breeding females but only 58% for gravid females, alongside relatively large amounts of substrate (14%) and macroalgae (13%). Satellite tracking of post-nesting green turtles from Chagos Archipelago in 2016 located foraging sites at Farquhar Atoll that coincided with capture locations of 26 of the 33 adult turtles sampled there in 1983. In situ surveys of those sites in 2018 revealed extensive nearly monospecific beds of T. ciliatum. The prominence of seagrass in the diet of green turtles and connectivity between foraging and nesting habitats throughout the region illustrate the need to conserve and monitor seagrass habitats of the Western Indian Ocean especially in the context of changing green turtle population densities.

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“…herbivory versus carnivory), which are unrelated to changes in spatial habitat use (shift from oceanic pelagic prey to neritic benthic prey). Four studies have investigated this question in C. caretta in Atlantic and Indian Ocean populations (Wallace et al, ; McClellan et al, ; Thomson et al, ; Hall et al, ); 19 studies in Atlantic C. mydas (Burgett et al, ; Cardona et al, ; Di Beneditto, Siciliano & Monteiro, ; Gillis et al, ; Gonzales Carman et al, ; Hancock et al, ; Howell et al, ; Velez‐Rubio et al, ; Williams et al, ), Pacific C. mydas (Arthur, ; Barceló, ; Lemons et al, ; Prior, Booth & Limpus, ; Rodríguez‐Barón, ; Sampson et al, ; Santos‐Baca, ; Shimada et al, ), and C. mydas in the Indian Ocean (Burkholder et al, ) and in the Mediterranean (Cardona et al, ); one study in Atlantic D. coriacea (Wallace et al, ), one study in E. imbricata (Ferreira et al, ), and one study in L. olivacea (Peavey et al, ).…”

Section: Resultsmentioning

confidence: 99%

“…A high‐protein diet derived from carnivory fuels the growth of early life stages, thus minimising time to maturity and attainment of a size refuge from predation (Werner & Gilliam, ; Werner, ; Werner & Hall, ; Werner & Anholt, ). Additionally, several studies found regional differences (Prior, Booth, & Limpus, ; Gillis et al, ) and inter‐individual differences in diet within the same life stage (Barceló, ; Burgett et al, ).…”

Section: Resultsmentioning

confidence: 99%

Beyond trophic morphology: stable isotopes reveal ubiquitous versatility in marine turtle trophic ecology

2019

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The idea that interspecific variation in trophic morphology among closely related species effectively permits resource partitioning has driven research on ecological radiation since Darwin first described variation in beak morphology among Geospiza.Marine turtles comprise an ecological radiation in which interspecific differences in trophic morphology have similarly been implicated as a pathway to ecopartition the marine realm, in both extant and extinct species. Because marine turtles are charismatic flagship species of conservation concern, their trophic ecology has been studied intensively using stable isotope analyses to gain insights into habitat use and diet, principally to inform conservation management. This legion of studies provides an unparalleled opportunity to examine ecological partitioning across numerous hierarchical levels that heretofore has not been applied to any other ecological radiation. Our contribution aims to provide a quantitative analysis of interspecific variation and a comprehensive review of intraspecific variation in trophic ecology across different hierarchical levels marshalling insights about realised trophic ecology derived from stable isotopes.We reviewed 113 stable isotope studies, mostly involving single species, and conducted a meta-analysis of data from adults to elucidate differences in trophic ecology among species. Our study reveals a more intricate hierarchy of ecopartitioning by marine turtles than previously recognised based on trophic morphology and dietary analyses. We found strong statistical support for interspecific partitioning, as well as a continuum of intraspecific trophic sub-specialisation in most species across several hierarchical levels. This ubiquity of trophic specialisation across many hierarchical levels exposes a far more complex view of trophic ecology and resource-axis exploitation than suggested by species diversity alone. Not only do species segregate along many widely understood axes such as body size, macrohabitat, and trophic morphology but the general pattern revealed by isotopic studies is one of microhabitat segregation and variation in foraging behaviour within species, within populations, and among individuals.These findings are highly relevant to conservation management because they imply ecological non-exchangeability, which introduces a new dimension beyond that of genetic stocks which drives current conservation planning.Perhaps the most remarkable finding from our data synthesis is that four of six marine turtle species forage across several trophic levels. This pattern is unlike that seen in other large marine predators, which forage at a single trophic level according to stable isotopes. This finding affirms suggestions that marine turtles are robust sentinels of ocean health and likely stabilise marine food webs. This insight has broader significance for studies of marine food webs and trophic ecology of large marine predators.Beyond insights concerning marine turtle ecology and conservation, our findings also have broader impli...

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Ontogenetic diet shifts of green sea turtles (Chelonia mydas) in a mid-ocean developmental habitat

Cited by 41 publications

References 58 publications

The Role of Vegetated Coastal Wetlands for Marine Megafauna Conservation

The Role of Vegetated Coastal Wetlands for Marine Megafauna Conservation

Green turtle diet is dominated by seagrass in the Western Indian Ocean except amongst gravid females

Beyond trophic morphology: stable isotopes reveal ubiquitous versatility in marine turtle trophic ecology

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