Factors Affecting the Long-Term Population Dynamics of Green Turtles (Chelonia mydas) in Ogasawara, Japan: Influence of Natural and Artificial Production of Hatchlings and Harvest Pressure

A total of 209 strandings of sea turtles (152 loggerhead turtles Caretta caretta, 42 green turtles Chelonia mydas, 15 unidentified) were recorded during the period 1984–2011 along the coasts of Rhodes (Aegean Sea, Greece). The proportion of dead to live individuals was different in the two species. Stranded Caretta caretta were larger than Chelonia mydas. The size range of stranded green turtles, usually juveniles, appeared to increase since 2000, including the largest specimens ever observed in Greek waters. For both species, a tendency to strand more frequently on the west coast of the island, along fishing ground areas, was noted. The higher incidence of loggerhead turtle strandings was observed in summer, while more green turtle strandings were documented in winter. Factors involved in the increased trend of stranding records of both species, along with the acceleration of this phenomenon in the last decade, are discussed. Data from Rhodes provide evidence that human activities detrimentally affect mainly larger-sized loggerhead turtles living in shallow waters.

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Spatial and temporal genetic variation among size classes of green turtles (Chelonia mydas) provides information on oceanic dispersal and population dynamics

Marine Ecology Progress Series ◽

10.3354/meps11521 ◽

2016 ◽

Vol 543 ◽

pp. 241-256 ◽

Cited By ~ 36

Author(s):

MP Jensen ◽

I Bell ◽

CJ Limpus ◽

M Hamann ◽

S Ambar ◽

...

Keyword(s):

Population Dynamics ◽

Genetic Variation ◽

Chelonia Mydas ◽

Size Classes ◽

Green Turtles ◽

Temporal Genetic Variation

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Long-term winter-site fidelity in Song Sparrows (Melospiza melodia)

The Auk ◽

10.1093/auk/ukz010 ◽

2019 ◽

Vol 136 (2) ◽

Author(s):

Tosha R Kelly ◽

Keith A Hobson ◽

Garth W Casbourn ◽

Elizabeth A MacDougall-Shackleton ◽

Scott A MacDougall-Shackleton

Keyword(s):

Population Dynamics ◽

Site Fidelity ◽

Migratory Birds ◽

Melospiza Melodia ◽

Factors Affecting ◽

Song Sparrows ◽

Breeding Grounds ◽

Wintering Areas ◽

Migratory Movements

Abstract In migratory animals, the degree to which individuals return to the same wintering sites across multiple years can affect fitness and population dynamics, and thus has important implications for conservation. Despite this, long-term evaluations of wintering-site fidelity are rare for migratory birds: many populations are intensively studied on their breeding grounds but tracking the migratory movements of small birds once they leave the breeding grounds is challenging. To evaluate patterns of overwintering location and fidelity, we collected winter-grown claw tissue from 301 Song Sparrows (Melospiza melodia; 449 samples) captured in spring at their breeding grounds over 6 consecutive yr and assessed stable hydrogen isotope (δ2Hc) values to determine within-individual repeatability and between-year variation in wintering latitudes. We also retrieved useable data from 8 geolocators over 2 consecutive winters. Geolocator-derived wintering positions correlated with origins based on δ2Hc values. Consistent with previous findings, male δ2Hc values reflected more northerly wintering areas than those of females, indicating shorter latitudinal migration distances for males, but the magnitude of the sex difference varied across years. The distribution of wintering latitudes was generally consistent among years, except for the 2015 舑2016 winter, which had unusually negative δ2Hc values. Values of δ2Hc were repeatable for males but not for females, suggesting that winter-site fidelity could differ between sexes. The data presented here emphasize the importance of tracking migratory populations across multiple years to uncover factors affecting population dynamics.

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Dietary preferences of juvenile green turtles (Chelonia mydas) on a tropical reef flat

Wildlife Research ◽

10.1071/wr05081 ◽

2006 ◽

Vol 33 (8) ◽

pp. 671 ◽

Cited By ~ 36

Author(s):

Mariana M. P. B. Fuentes ◽

Ivan R. Lawler ◽

Emma Gyuris

Keyword(s):

Reef Flat ◽

Chelonia Mydas ◽

Thalassia Hemprichii ◽

Factors Affecting ◽

Green Turtles ◽

Diet Switching ◽

Dietary Preferences ◽

Tropical Reef ◽

Potential Factors ◽

Feeding Choices

We offer the first published description of the feeding choices made by juvenile green turtles on a tropical feeding ground, in this case a reef flat environment. We collected 85 lavage samples from 76 turtles and compared the food eaten to the food resources available. Resampling of some individuals enabled us to gain preliminary insights into diet switching by juvenile turtles. The area of the reef flat at Green Island, Queensland, Australia, had similar proportions of coverage by seagrasses (52%) and by algae (48%). Seven species of seagrass and at least 26 species of algae were identified. The dominant seagrasses, on an area basis, were Cymodocea sp. (29.7%), Halodule sp. (11.1%), Thalassia sp. (6.4%) and Syringodium sp. (4.5%). The most dominant algae were Halimeda spp. (10.2%). and Galaxaura sp. (7.25%). Most juvenile green turtles ate primarily seagrass, but some individuals ate predominantly algae. The turtles showed clear preferences for the seagrass Thalassia hemprichii and the algae Gracilaria spp., Gelidiella sp., Hypnea spp. despite their low abundance in many cases. Ways to improve our understanding of preferences and possible diet switching, and potential factors affecting them, are discussed.

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Design of a Sampling Plan for Studies on the Population Dynamics of the Diamondback Moth, Plutella maculipennis (Curt.) (Lepidoptera: Plutellidae)

The Canadian Entomologist ◽

10.4039/ent93820-9 ◽

1961 ◽

Vol 93 (9) ◽

pp. 820-831 ◽

Cited By ~ 35

Author(s):

D. G. Harcourt

Keyword(s):

Population Dynamics ◽

Diamondback Moth ◽

Sampling Plan ◽

Immature Stages ◽

Mortality Factors ◽

Term Study ◽

Factors Affecting ◽

Long Term Study ◽

Successive Generations

In 1958, intensive studies on the population dynamics of the diamondback moth, Plutella maculipennis (Curt.), on cabbage were initiated in long-term study plots at Merivale, Ontario. The object was to construct ecological life tables (Morris and Miller, 1954) for successive generations of the insect, and, ultimately, to develop a mathematical model describing survival of field populations. This paper reports on the variation between samples of immature stages of the moth, and between some of the mortality factors affecting its abundance, and on the use of these data in designing a sampling plan with acceptable limits of precision.

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Expanding the coastal forager paradigm: long-term pelagic habitat use by green turtles Chelonia mydas in the eastern Pacific Ocean

Marine Ecology Progress Series ◽

10.3354/meps12372 ◽

2018 ◽

Vol 587 ◽

pp. 217-234 ◽

Cited By ~ 14

Author(s):

CN Turner Tomaszewicz ◽

JA Seminoff ◽

L Avens ◽

LR Goshe ◽

JM Rguez-Baron ◽

...

Keyword(s):

Pacific Ocean ◽

Habitat Use ◽

Chelonia Mydas ◽

Eastern Pacific ◽

Eastern Pacific Ocean ◽

Green Turtles ◽

Pelagic Habitat

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Design of a Sampling Plan for Studies on the Population Dynamics of the Imported Cabbageworm, Pieris rapae (L.) (Lepidoptera: Pieridae)

The Canadian Entomologist ◽

10.4039/ent94849-8 ◽

1962 ◽

Vol 94 (8) ◽

pp. 849-859 ◽

Cited By ~ 15

Author(s):

D. G. Harcourt

Keyword(s):

Population Dynamics ◽

Pieris Rapae ◽

Sampling Plan ◽

Immature Stages ◽

Mortality Factors ◽

Term Study ◽

Factors Affecting ◽

Long Term Study ◽

Successive Generations

In 1958, intensive studies on the population dynamics of the imported cabbageworm, Pieris rapae (L.), on cabbage were initiated in long-term study plots at Merivale, Ontario. The object was to construct ecological life tables for successive generations of the species, and ultimately, to develop mathematical models describing survival of field populations. This paper reports on the variation between samples of immature stages of the insect, and between some of the mortality factors affecting its abundance; it further illustrates the use of these data in designing a sampling plan with acceptable limits of precision.

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Change in body mass associated with long-term fasting in a marine reptile: the case of green turtles (Chelonia mydas) at Ascension Island

Canadian Journal of Zoology ◽

10.1139/z02-110 ◽

2002 ◽

Vol 80 (7) ◽

pp. 1299-1302 ◽

Cited By ~ 45

Author(s):

Graeme C Hays ◽

Annette C Broderick ◽

Fiona Glen ◽

Brendan J Godley

Keyword(s):

Mass Loss ◽

Body Mass ◽

Chelonia Mydas ◽

Green Sea Turtles ◽

Green Turtles ◽

Ascension Island ◽

Pinniped Species ◽

Marine Reptile ◽

Nesting Season

Female green sea turtles (Chelonia mydas) nesting at Ascension Island (7°57'S, 14°22'W) in the middle of the Atlantic Ocean had a mean body mass (post oviposition) of 166.3 kg (range 107.5243.5 kg, n = 119). Individuals lost mass slowly during the nesting season (mean mass loss 0.22 kg·d1, n = 14 individuals weighed more than once). Gut-content analysis and behavioural observations indicated a lack of feeding. Females of equivalent-sized pinniped species that also do not feed while reproducing (nursing pups) on islands lose mass about 17 times faster. This comparatively low rate of mass loss by green turtles probably reflects their ectothermic nature and, consequently, their low metabolic rate. We estimate that a female turtle would lose only 19% of her body mass during the 143-day, 4400-km round trip from Brazil if she did not eat, laid 3 clutches of eggs, and lost 0.22 kg·d1.

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Foraging Habits of Green Sea Turtles (Chelonia mydas) in the Northwestern Gulf of Mexico

Frontiers in Marine Science ◽

10.3389/fmars.2021.658368 ◽

2021 ◽

Vol 8 ◽

Author(s):

Lyndsey N. Howell ◽

Donna J. Shaver

Keyword(s):

Gulf Of Mexico ◽

Green Turtle ◽

Carapace Length ◽

Foraging Ecology ◽

Chelonia Mydas ◽

Foraging Habitat ◽

Seagrass Meadows ◽

Green Sea Turtles ◽

Green Turtles

Knowledge of green turtle (Chelonia mydas) foraging ecology in the northwestern Gulf of Mexico (GOM) is critical as populations begin to recover from heavy harvesting in prior centuries. We present a comprehensive long-term assessment of green turtle diets from carcasses salvaged from 1987 to 2014 along the Texas coast. Digestive tract contents were examined from 420 green turtles, ranging in size from 7.3 to 86.0 cm in straight carapace length (SCLmax). Green turtles as small as 16.2 cm SCLmax recruit from the oceanic environment to nearshore foraging habitat in the northwestern GOM and consume macroalgae principally. A successive shift in diet and habitat to inshore seagrasses was evident by the seagrass-dominated diet of turtles larger than 30 cm SCLmax. Animal matter remained a frequently ingested diet item suggesting these immature green turtles are better classified as omnivores. The overall evidence indicates that Texas’ recovering green turtle assemblage is exhibiting foraging plasticity within seagrass meadows changing species composition and density.

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