Patterns and intensity of ghost crab predation on the nests of an important endangered loggerhead turtle population

Marco, Adolfo; Graça, Jesemine da; García-Cerdá, Rosa María; Abella, Elena; Freitas, Rui

doi:10.1016/j.jembe.2015.03.010

Cited by 53 publications

(46 citation statements)

References 44 publications

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“…Commonly known as ghost crabs due to their nocturnality and their generally pale colouration that blends in well with the sand (Karleskint et al 2009), they are predators of small animals, including early juveniles of turtles, and generalist scavengers, whose cleaning activity makes them important components of sandy beach food webs (Trott 1999;Valero-Pacheco et al 2007;Türeli et al 2009;Lucrezi & Schlacher 2014;Marco et al 2015). Being negatively affected by human activities, they also constitute valuable ecological indicators for quickly assessing the impact of disturbance on beach habitats (Branco et al 2010;Schlacher et al 2011;Noriega et al 2012;Jonah et al 2015;Lucrezi 2015).…”

Section: Introductionmentioning

confidence: 99%

The protected taxon Ocypode cursor (Linnaeus, 1758) (Crustacea: Decapoda: Ocypodidae) – documenting its well-established presence in the central Mediterranean

Deidun

Crocetta

Sciberras³

et al. 2017

The European Zoological Journal

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Ocypode cursor (Linnaeus, 1758) is the only Ocypode species present in the Mediterranean Sea, and one of the nine marine crustacean species protected in the basin. It is widely distributed in the eastern Mediterranean, but knowledge about its presence in the central Mediterranean is very limited so far. We hereby first document the established presence of O. cursor in the central Mediterranean (Sicily and Malta), backdate the known presence of this taxon in Italy, and offer preliminary observations on the main known Maltese population. In Sicily, O. cursor is distributed along most of the south-western coast of the island of Sicily, whilst at least three beaches in the Maltese Islands are known to support populations of this species. The main Maltese population exhibits numerous similarities (e.g. burrow width, zonation along the beach) to another Mediterranean population studied in northern Cyprus, although occurring at lower densities. We conclude that the species has been probably present within the study area for a long period, but went undetected in view of the low population densities at which it previously occurred, the lack of a comprehensive census for the species within the same study area, and its nocturnal habits. The presence of this species in the central Mediterranean seems to be attributable to secondary natural spreading.

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Section: Introductionmentioning

confidence: 99%

The protected taxon Ocypode cursor (Linnaeus, 1758) (Crustacea: Decapoda: Ocypodidae) – documenting its well-established presence in the central Mediterranean

Deidun

Crocetta

Sciberras³

et al. 2017

The European Zoological Journal

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“…For example, the final number of offspring and, thus, the reproduction success of the organism are dependent on the percentage of ova that are fertilized and commence development. However, there are many biotic and abiotic factors that affect hatching success by causing embryo mortality during the incubation on the beach (Patino-Martinez et al, 2014;Marco et al, 2015;Sarmiento-Ramírez et al, 2014;De Andrés et al, 2016). Even, the percentage of unfertile eggs may negatively affect development of viable eggs within the nest, because they usually decompose and are colonised by microorganisms that may invade the viable eggs and eventually affect their hatching success (Blanck Sawyer, 1981;Phillott Parmenter, 2001;Sarmiento-Ramírez et al, 2010.…”

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confidence: 99%

Non-invasive monitoring of the fertilization rate in sea turtle nests: comparison between two techniques

Abella¹,

García-Cerdá

Marco

2017

bah

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Egg fertilization rate is a defining event in the life history of oviparous species. However, for many terrestrial oviparous species, this parameter is only estimated after hatching and emergence of hatchlings, by studying evidence of embryonic development in unhatched eggs. We compared the accuracy of this method with a second technique based on the careful excavation of sea turtle nests within the first 96 hours of oviposition and calculating the proportion of alive eggs, where a clear white spot is externally visible in the shell. Both methods underestimate the fertility rate but we are not aware of any other alternative on-invasive technique. The study was conducted in a nesting population of loggerhead turtles (Caretta caretta) at Boa Vista Island (Republic of Cabo Verde). We found significant differences in the estimation of fertilization rate between both techniques. When inspecting eggs after hatching, researchers significantly overestimated the number of unfertilized eggs and this calculation was not correlated with the estimation based on examination of eggs soon after oviposition. The first estimate was not correlated with hatching success or hatchling phenotype. There was no relationship between the number of viable embryos at oviposition and the hatching success and the hatchling's phenotype. The absence of embryo or its early death had no effect on survival of developing embryos within a nest. Fertilization rate in loggerheads did not show spatial or temporal variation during nesting season. We suggest the implementation in sea turtle nesting monitoring programs of annual less-invasive estimation of egg fertilization rate based on the excavation of a sample of representative nests immediately after the formation of the white spot in the shell of developing embryos.

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“…7: 200327 chemosensory cues present around nests soon after laying [39]. For example, it may function better against predation by Asian mongooses (Herpestes javanicus), which predate most hawksbill nests soon after laying [9], than ghost crabs, which predate most loggerhead turtle (Caretta caretta) nests when eggs are hatching [44].…”

Section: Discussionmentioning

confidence: 99%

Buried treasure—marine turtles do not ‘disguise’ or ‘camouflage’ their nests but avoid them and create a decoy trail

et al. 2020

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After laying their eggs and refilling the egg chamber, sea turtles scatter sand extensively around the nest site. This is presumed to camouflage the nest, or optimize local conditions for egg development, but a consensus on its function is lacking. We quantified activity and mapped the movements of hawksbill ( Eretmochelys imbricata ) and leatherback ( Dermochelys coriacea ) turtles during sand-scattering. For leatherbacks, we also recorded activity at each sand-scattering position. For hawksbills, we recorded breathing rates during nesting as an indicator of metabolic investment and compared with published values for leatherbacks. Temporal and inferred metabolic investment in sand-scattering was substantial for both species. Neither species remained near the nest while sand-scattering, instead moving to several other positions to scatter sand, changing direction each time, progressively displacing themselves from the nest site. Movement patterns were highly diverse between individuals, but activity at each sand-scattering position changed little between completion of egg chamber refilling and return to the sea. Our findings are inconsistent with sand-scattering being to directly camouflage the nest, or primarily for modifying the nest-proximal environment. Instead, they are consistent with the construction of a series of dispersed decoy nests that may reduce the discovery of nests by predators.

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Patterns and intensity of ghost crab predation on the nests of an important endangered loggerhead turtle population

Cited by 53 publications

References 44 publications

The protected taxon Ocypode cursor (Linnaeus, 1758) (Crustacea: Decapoda: Ocypodidae) – documenting its well-established presence in the central Mediterranean

The protected taxon Ocypode cursor (Linnaeus, 1758) (Crustacea: Decapoda: Ocypodidae) – documenting its well-established presence in the central Mediterranean

Non-invasive monitoring of the fertilization rate in sea turtle nests: comparison between two techniques

Buried treasure—marine turtles do not ‘disguise’ or ‘camouflage’ their nests but avoid them and create a decoy trail

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