Factors influencing variations of oxygen content in nests of green sea turtles during egg incubation with a comparison of two nesting environments

Cheng, I-Jiunn; Lin, Chia-hua; Tseng, Cheng-Tsung

doi:10.1016/j.jembe.2015.05.013

Cited by 22 publications

(16 citation statements)

References 47 publications

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“…For the majority of our monitored nests, PO 2 and PCO 2 was similar to sand values, and similar to atmospheric air as is usual for sea turtle nests early in incubation [ 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 ]. However, in two of our nests NG31 and NG48, PO 2 and PCO 2 were conspicuously different to other nests.…”

Section: Discussionsupporting

confidence: 77%

“…Although we do not know of any studies that have experimentally examined the effect of depressed PO 2 and elevated PCO 2 on newly laid sea turtle eggs, we are confident that the deviations from atmospheric conditions we observed were not extreme enough to adversely influence embryonic development. We base this conclusion on studies that have reported field nest measurements of respiratory gases and also reported high hatching success from these nests [ 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 ]. This indicates that, at least for the 2016–2017 nesting season, the amount of organic matter residing in beach sand was not great enough to fuel a microbial respiratory load that could cause a significant depression in oxygen and elevation of carbon dioxide across the beach at green turtle nest level.…”

Section: Discussionmentioning

confidence: 97%

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A preliminary investigation into the early embryo death syndrome (EEDS) at the world’s largest green turtle rookery

Booth

Dunstan

2018

PLoS ONE

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Raine Island hosts the largest nesting aggregation of green turtles in the world, but nest emergence success and hence recruitment of hatchlings off the beach appear to have significantly declined since the 1990s. Nests destroyed by subsequent nesting turtles, and nest failure due to flooding account for most of the nest failure, but many nests still have poor hatch success even when undisturbed and flood-free. In undisturbed, flood-free nests that experience high mortality, embryos typically die at a very early stage of development, a phenomenon we term early embryo death syndrome (EEDS). Previous research indicates that EEDS is correlated with the number of females nesting at Raine Island during a nesting season. Here, we monitor nest temperature and oxygen (PO2) and carbon dioxide (PCO2) partial pressures during the first week after nest construction to discover if they are associated with EEDS. Our investigation found that the proportion of early embryo death was greatest in two nests that experienced the highest nest temperature, lowest PO2 and highest PCO2 during the first week of incubation suggesting that these variables either by themselves or in combination may be the underlying cause of EEDS. These two nests were located adjacent to maturing nests, so the high temperature and more extreme PO2s and PCO2s are most likely to be caused by the combined metabolism of embryos in the mature nests. Although this conclusion is based on just two nests and needs to be substantiated in future studies, it would appear that the laying of new nests in the close location to mature nests could be a significant cause of hatch failure at high density nesting sea turtle rookeries around the world.

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Section: Discussionsupporting

confidence: 77%

Section: Discussionmentioning

confidence: 97%

A preliminary investigation into the early embryo death syndrome (EEDS) at the world’s largest green turtle rookery

Booth

Dunstan

2018

PLoS ONE

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“…Parker and Begon (1986) predicted that optimal egg size increases with female body size when clutch size is negatively correlated with offspring survival. Because neritic foragers lay larger clutches than those of oceanic foragers, their embryos and hatchlings might suffer from more-severe hypoxia within a nest due to greater oxygen demands for metabolism, as has been shown in green turtle (Cheng et al 2015) and leatherback turtle (Dermochelys coriacea) nests (Wallace et al 2004). We could not, however, find significant negative correlations between the number of eggs reburied in a nest and emergence success in both oceanic and neritic foragers.…”

Section: Discussionmentioning

confidence: 99%

Loggerhead turtle (Caretta caretta) offspring size does not vary with maternal alternative foraging behaviors: support for their phenotypic plasticity

2015

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classified based on stable isotope ratios, suggesting that the development process of hatchling tissue from yolk and albumen is genetically similar between the two groups. Egg size and mass significantly increased with female body size only in neritic foragers that laid larger clutches than oceanic foragers, whereas hatchling size and mass significantly increased with egg mass in both groups. This suggested that larger females produced larger hatchlings within neritic foragers, and indeed, there was a significant positive correlation in body size between females and hatchlings only within neritic foragers. However, significant negative correlations between the number of eggs reburied per nest and emergence success that might explain the above phenomenon were not found in either oceanic or neritic foragers. Effects of a seasonal rise in ambient temperature on embryonic development and hatchling morphology were also similar between the two foraging groups, implying their genetic similarity in thermal response, consistent with their phenotypic plasticity.

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“…This effect, in turn, influences the reproductive output and eggs per clutch [ 13 , 30 , 42 , 49 – 51 ]. Although the nesting environments are different between the two islands [ 7 ], the similar remigration intervals indicated similar responses to global climate change during the study period. Both populations using the same foraging area is another possibility; however, animal were tracked with satellite telemetry showed that two populations had different foraging sites ( Fig 3 ).…”

Section: Resultsmentioning

confidence: 99%

“…Political conflicts in the region and limited funding impede research opportunities on sea turtle ecology and the threats that they face, particularly in Taiwan, despite great effort devoted to the nesting ecology of sea turtles at the primary nesting sites e.g. [ 4 – 7 ].…”

Section: Introductionmentioning

confidence: 99%

Geographically closed, yet so different: Contrasting long-term trends at two adjacent sea turtle nesting populations in Taiwan due to different anthropogenic effects

Cheng

Chan

2018

PLoS ONE

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Marine turtles are endangered megafauna that face both natural disturbances and anthropogenic threats. The islands of Wan-an and Lanyu support two important green turtle nesting populations in Taiwan and are separated by 250 km. Nesting activity was first documented on Wan-an Island in 1992, with 8 nesting females being documented. A further 11 nesting females were first documented on Lanyu Island in 1997. However, by 2015, the Wan-an Island population declined to only 2 nesting females, whereas the Lanyu Island population showed peaks in abundance (up to 24 nesters) every 3–5 years with no long-term decline. Additionally, the recruitment of new nesters to the Wan-an Island population decreased to 15%, whereas recruitment into the Lanyu Island population remained high (66%). The decrease of the nesting population on Wan-an Island might be due to illegal poaching on the high seas along the migratory corridor of the turtles, whereas the stable nesting population on Lanyu Island showed no evidence of such a threat. The two nesting populations use different migratory corridors to their foraging grounds, resulting in different fates of development in population trend.

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Factors influencing variations of oxygen content in nests of green sea turtles during egg incubation with a comparison of two nesting environments

Cited by 22 publications

References 47 publications

A preliminary investigation into the early embryo death syndrome (EEDS) at the world’s largest green turtle rookery

A preliminary investigation into the early embryo death syndrome (EEDS) at the world’s largest green turtle rookery

Loggerhead turtle (Caretta caretta) offspring size does not vary with maternal alternative foraging behaviors: support for their phenotypic plasticity

Geographically closed, yet so different: Contrasting long-term trends at two adjacent sea turtle nesting populations in Taiwan due to different anthropogenic effects

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