Green turtle ( Chelonia mydas (L.)) nesting activity at Aldabra Atoll

1979 ◽  
Vol 286 (1011) ◽  
pp. 255-263 ◽  
Keyword(s):  
Green Turtle ◽  
Chelonia Mydas ◽  
Human Settlements ◽  
Southwest Coast ◽  
Annual Variations ◽  
Recent Increase ◽  
Nesting Sites ◽  
Nesting Activity ◽  
Nesting Beaches

Green turtle ( Chelonia mydas ) nesting activity was indirectly monitored at the nesting sites at Aldabra by counting turtle tracks and nest pits during 11 months. Nesting activity took place throughout the year but a prolonged peak season was observed on southwest coast beaches between July and October, and less consistent peaks were observed for other beaches in February and March and from May to August. Estimations based on track and pit counts suggest that about 700 turtles nested at Aldabra during the year. Although annual variations may occur, this is similar to earlier estimates and does not suggest any recent increase. The distribution of turtle emergences among nesting beaches suggests that beaches fall into distinct nesting areas that are utilized to different extents. The distribution of turtle emergences on the largest beach suggests that human settlements may be reducing nesting there.

Hawksbill turtle (Eretmochelys imbricata Linnaeus 1766) and green turtle (Chelonia mydas Linnaeus 1754) nesting activity (2002-2004) at El Cuyo beach, Mexico

2006 ◽  
Vol 27 (4) ◽  
pp. 539-547 ◽  
Author(s):  
Raquel Xavier ◽  
Andre Barata ◽  
Leopoldo Palomo Cortez ◽  
Nuno Queiroz ◽  
Eduardo Cuevas
Keyword(s):  
Green Turtle ◽  
Average Distance ◽  
Biosphere Reserve ◽  
Chelonia Mydas ◽  
Eretmochelys Imbricata ◽  
Nest Location ◽  
Hurricane Ivan ◽  
Green Turtles ◽  
Nest Site Fidelity ◽  
Nesting Activity

Abstract The Yucatan Peninsula nesting hawksbill turtles' population (Eretmochelys imbricata Linnaeus 1766) is the biggest in the Caribbean and fourth in the world; within the Ría Lagartos Biosphere Reserve, at El Cuyo beach both hawksbill and green turtle (Chelonia mydas Linnaeus 1754) nest. In the present study, the nesting trend and reproductive output of both species during three consecutive nesting seasons (2002-2004) was evaluated. Night patrols from mid April to September allowed the collection of data on number of nests, nest location and size of females. The number of hawksbill and green turtles' nests decreased along these seasons. No differences were found in mean length of female turtles of both species between nesting seasons. Both species showed high nest site fidelity with average distance between nests of 3 km for Hawksbill and 1.8 km for Green turtles. The regression analysis between size and fecundity was significant (p < 0.05) for both species. The spatial variation of laid nests was also analyzed revealing that both species nested mainly on the dune zone. Predation has risen on El Cuyo beach, affecting mostly hawksbills nests. Hurricane Ivan destroyed the majority of green turtles nests in 2004.

scholarly journals Cayman Islands Sea Turtle Nesting Population Increases Over 22 Years of Monitoring

2021 ◽  
Vol 8 ◽  
Author(s):  
Janice M. Blumenthal ◽  
Jane L. Hardwick ◽  
Timothy J. Austin ◽  
Annette C. Broderick ◽  
Paul Chin ◽  
...  
Keyword(s):  
Spatial Data ◽  
Green Turtle ◽  
Chelonia Mydas ◽  
Sea Turtle ◽  
Conservation Strategies ◽  
Percentage Increase ◽  
Cayman Islands ◽  
Grand Cayman ◽  
Loggerhead Turtles ◽  
Nesting Beaches

Given differing trajectories of sea turtle populations worldwide, there is a need to assess and report long-term population trends and determine which conservation strategies are effective. In this study, we report on sea turtle nest monitoring in the Cayman Islands over a 22-year period. We found that green (Chelonia mydas) and loggerhead (Caretta caretta) nest numbers increased significantly across the three islands since monitoring began in 1998, but that hawksbill nest numbers remained low with a maximum of 13 nests recorded in a season. Comparing the first 5 years of nest numbers to the most recent 5 years, the greatest percentage increase in green turtle nests was in Grand Cayman from 82 to 1,005 nests (1,126%), whereas the greatest percentage increase for loggerhead turtle nests was in Little Cayman from 10 to 290 nests (3,800%). A captive breeding operation contributed to the increase in the Grand Cayman green turtle population, however, loggerhead turtles were never captive-bred, and these populations began to increase after a legal traditional turtle fishery became inactive in 2008. Although both species have shown significant signs of recovery, populations remain at a fragment of their historical level and are vulnerable to threats. Illegal harvesting occurs to this day, with multiple females taken from nesting beaches each year. For nests and hatchlings, threats include artificial lighting on nesting beaches, causing hatchlings to misorient away from the sea, and inundation of nests by seawater reducing hatch success. The impacts of lighting were found to increase over the monitoring period. Spatial data on nest distribution was used to identify critical nesting habitat for green and loggerhead turtles and is used by the Cayman Islands Department of Environment to facilitate remediation of threats related to beachside development and for targeted future management efforts.

Green turtle mitochondrial microsatellites indicate finer-scale natal homing to isolated islands than to continental nesting sites

2020 ◽  
Vol 643 ◽  
pp. 159-171 ◽  
Author(s):  
BM Shamblin ◽  
KM Hart ◽  
KJ Martin ◽  
SA Ceriani ◽  
DA Bagley ◽  
...  
Keyword(s):  
Green Turtle ◽  
National Park ◽  
Mitochondrial Control Region ◽  
Chelonia Mydas ◽  
Great Promise ◽  
Natal Philopatry ◽  
Dry Tortugas ◽  
Key West ◽  
Natal Homing ◽  
Nesting Sites

In highly mobile philopatric species, defining the scale of natal homing is fundamental to characterizing population dynamics and effectively managing distinct populations. Genetic tools have provided evidence of regional natal philopatry in marine turtles, but extensive sharing of maternally inherited mitochondrial control region (CR) haplotypes within regions (<500 km) often impedes identification of population boundaries. Previous CR-based analyses of Florida (USA) green turtle Chelonia mydas nesting sites detected at least 2 populations, but the ubiquity of haplotype CM-A3.1 among southern rookeries decreased the power to detect differentiation. We reassessed population structure by sequencing the mitochondrial microsatellite (short tandem repeat, mtSTR) in 786 samples from 11 nesting sites spanning 700 km from Canaveral National Seashore through Dry Tortugas National Park. The mtSTR marker subdivided CM-A3.1 into 12 haplotypes that were structured among rookeries, demonstrating independent female recruitment into the Dry Tortugas and Marquesas Keys nesting populations. Combined haplotypes provided support for recognition of at least 4 management units in Florida: (1) central eastern Florida, (2) southeastern Florida, (3) Key West National Wildlife Refuge, and (4) Dry Tortugas National Park. Recapture data indicated female nesting dispersal between islands <15 km apart, but haplotype frequencies demonstrated discrete natal homing to island groups separated by 70 km. These isolated insular rookeries may be more vulnerable to climate change-mediated nesting habitat instability than those along continental coasts and should be monitored more consistently to characterize population status. Broader application of the mtSTR markers holds great promise in improving resolution of stock structure and migratory connectivity for green turtles globally.

Green turtle (Chelonia mydas) nesting on Atol das Rocas, north-eastern Brazil, 1990–2008

2012 ◽  
Vol 93 (4) ◽  
pp. 1117-1132 ◽  
Author(s):  
Claudio Bellini ◽  
Armando J.B. Santos ◽  
Alice Grossman ◽  
Maria A. Marcovaldi ◽  
Paulo C. R. Barata
Keyword(s):  
Green Turtle ◽  
Carapace Length ◽  
Temporal Distribution ◽  
Chelonia Mydas ◽  
Sea Turtle ◽  
Annual Number ◽  
Eastern Brazil ◽  
North Eastern ◽  
The Mean ◽  
Nesting Activity

In this paper, information is presented on green turtle (Chelonia mydas) nesting on Atol das Rocas (Rocas Atoll), north-eastern Brazil. The temporal distribution of nesting events per season, annual number of nests, carapace length of nesting females, clutch size, hatching success, incubation period, internesting interval, clutch frequency, observed reproductive lifespan, and remigration period are reported. The study period included the nesting seasons from 1990 to 2008, but no regular beach monitoring was carried out in 1998 and 1999. Two sorts of methods were applied to the estimation of the annual number of nests in some seasons. Taking into account the estimated annual numbers of nests, the mean annual number of nests in the study period, excluding 1998–1999, was 335 (standard deviation = 139, range = 136–563, N = 17). An analysis of the available data indicates that the average nesting levels at the beginning of the study period (the first five seasons) and at its end (the last five seasons) were roughly the same. The mean curved carapace length of the nesting turtles decreased significantly during the study period, from 115.9 cm in 1990–1992 to 112.9 cm in 2006–2008. Atol das Rocas was established as a federal biological reserve in 1979, but regular sea turtle conservation activities actually started there in 1990. Since that year, the killing of nesting turtles has ceased, nesting activity by the turtles can proceed in an undisturbed fashion, and their clutches can incubate in a protected environment.

scholarly journals Plasma Analysis in Normal Green Sea Turtles, Chelonia mydas, During two Different Periods of Nesting at Ras Al- Hadd, Sultanate of Oman

2001 ◽  
Vol 6 (1) ◽  
pp. 21
Author(s):  
Abdulaziz.Y.A. AlKindi ◽  
Ibrahim.Y. Mahmoud ◽  
Humaid Khan
Keyword(s):  
Uric Acid ◽  
Total Protein ◽  
Sea Turtles ◽  
Plasma Concentrations ◽  
Chelonia Mydas ◽  
Peak Period ◽  
Normal Green ◽  
Nesting Sites ◽  
High Concentrations ◽  
Nesting Activity

Plasma composition which includes total protein, cholesterol, lactate, glucose, uric acid, urea, CO2, and electrolytes (Ca++, K+, Na+, Mg++, PO4-3, Cl-), and plasma osmolarity were analyzed in normal adult nesting green turtles Chelonia mydas. Blood samples were collected in June-October at the peak of the nesting season and in November-May during the non-peak period. Plasma electrolytes values, except for PO4-3 and Cl- were significant between the two periods. Values for total proteins and uric acid were significantly different during the two periods but urea values were insignificant. Osmolarity was unchanged during the two periods. During nesting the sea turtles undergo strenuous and exhaustive exercise and like other lung breathing reptiles, they ventilate intermittently, thus, they rely on anaerobic metabolism during the nesting exercise. Plasma concentrations of lactate and CO2 were significant but glucose values remained stable and unchanged during the two nesting periods. Higher concentrations of total protein during June compared to October may be related to the type and the availability of diet in the waters near the nesting sites. High concentrations of electrolytes and lactate are perhaps related to more stressful conditions during June because of higher crowding and intense competition for nesting sites. The aim of this study was to analyze the role of these parameters during nesting activity to evaluate changes under two different crowding conditions and gather information for future population health assessments.

scholarly journals Biophysical factors influencing the choice of nesting sites by the green turtle (Chelonia mydas) on the Kenyan coast

2019 ◽  
Vol 18 (2) ◽  
pp. 45-55
Author(s):  
Fridah D. Obare ◽  
Robert Chira ◽  
Dorcus Sigana ◽  
Andrew Wamukota
Keyword(s):  
Human Activities ◽  
Vegetation Cover ◽  
Green Turtle ◽  
Chelonia Mydas ◽  
Management Tool ◽  
Factors Influencing ◽  
Biophysical Factors ◽  
Beach Width ◽  
Nesting Sites ◽  
Kenyan Coast

The green turtle (Chelonia mydas) is the most common sea turtle nesting along Kenya’s coastline. Varying biophysical factors influence choice of nesting sites where eggs are laid. This study was conducted between February and November 2016 and was designed to establish the relationship between numbers of C. mydas nests on the beach and biophysical variables such as vegetation cover, organic matter content (OMC), beach width, and beach slope. Multiple regression analysis was employed to assess the factors that contribute to the number of C. mydas nests on a beach. This analysis did not allow prediction of the number of nests in a statistically significant way (F (4, 26) = 0.094, p > 0.05, R = 0.120). However, there was a decrease in the number of nests with increased vegetation cover (b = - 0.013), OMC (b = - 8.114), beach width (b = - 0.089) and slope of the beach (b = - 0.352). Approximately 70% of nests occurred on beaches with medium and fine sand. Beaches with intense human activities were associated with high OMC which significantly affected the number of nests on the beach. It is therefore recommended that existing laws should be enforced to control beach development and human activities along the Kenyan coast to protect nest sites. Additionally, long term monitoring should be put in place to evaluate the impact of human disturbance on the favourable biophysical factors influencing the number of nests on a beach, as a management tool in the conservation of C. mydas. 

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