scholarly journals Newly Discovered migratory corridor and foraging ground for Atlantic green turtles, Chelonia mydas, nesting on Bioko Island, Equatorial Guinea

2019 ◽  
Author(s):  
Emily Mettler ◽  
Chelsea E. Clyde-Brockway ◽  
Shaya Honarvar ◽  
Frank V. Paladino
Keyword(s):  
Coastal Waters ◽  
Satellite Telemetry ◽  
State Space Model ◽  
Chelonia Mydas ◽  
Equatorial Guinea ◽  
Bioko Island ◽  
Green Turtles ◽  
Satellite Transmitters ◽  
Anthropogenic Threats ◽  
Polluted Waters

AbstractThis study is the first to use satellite telemetry to track post-nesting movements of endangered green turtles (Chelonia mydas) in the Gulf of Guinea. Satellite transmitters were attached in 2018 to six Atlantic green turtles nesting on Bioko Island, Equatorial Guinea, to track their post-nesting movements and locate their foraging grounds. Track lengths of 20-198 days were analyzed, for a total of 536 movement days for the six turtles. Migratory pathways and foraging grounds were identified by applying a switching state space model to locational data, which provides daily position estimates to identify shifts between migrating and foraging behavior. Turtles exhibited a combination of coastal and oceanic migrations pathways that ranged from 957 km to 1,131 km. Of the six turtles, five completed their migration and maintained residency at the same foraging ground near the coastal waters of Accra, Ghana until transmission was lost. These five resident turtles inhabit heavily fished and polluted waters and are vulnerable to a variety of anthropogenic threats. The identification of these foraging grounds highlights the importance of these coastal waters for the protection of the endangered Atlantic green turtle.

scholarly journals The Effects of Nest Location and Beach Environment on Hatching Success for Leatherback (Dermochelys Coriacea) and Green (Chelonia Mydas) Sea Turtles on Bioko Island, Equatorial Guinea

2021 ◽  
Author(s):  
Callie A. Veelenturf ◽  
Elizabeth M. Sinclair ◽  
Peter Leopold ◽  
Frank V. Paladino ◽  
Shaya Honarvar
Keyword(s):  
Green Turtle ◽  
Hatching Success ◽  
Sea Turtles ◽  
Chelonia Mydas ◽  
Dermochelys Coriacea ◽  
Equatorial Guinea ◽  
Leatherback Turtles ◽  
Nest Location ◽  
Bioko Island ◽  
Elevation Range

Abstract Hatching success in sea turtles is hindered by a variety of biotic and abiotic factors. This study of the nesting ecology of leatherback (Dermochelys coriacea) and green (Chelonia mydas) sea turtles, investigated how several environmental factors and beach characteristics on Bioko Island, Equatorial Guinea influence sea turtle reproductive success. Average clutch hatching success was 40.4% for green turtles and 41.73% for leatherback turtles. For leatherback turtles, clutch elevation relative to the high tide line (HTL) was found to be the most influential factor in determining hatching success, highlighting the sensitivity of this species to sea level rise (SLR). Multiple linear regression analysis demonstrated that nest distance to vegetation and sand conductivity also played significant roles in leatherback clutch hatching success. For leatherback clutches, 33% percent of experimental nests were affected by inundation and 17% by predation. An optimum clutch elevation range for leatherback turtles was identified, where a distinct increase in hatching success was observed between -0.286 m to -0.0528 m above the HTL. For green sea turtles, 64% of experimental nests were affected by predation, confounding conclusions about the roles of environmental characteristics in green turtle hatching success. We propose further investigation into influential characteristics in green turtle nests and confirmation of the observed optimum elevation range on Bioko Island and other nesting grounds. Identified sensitivities of each species to SLR and beach characteristics will be used to encourage the government of Equatorial Guinea to consider the vulnerability of their resident turtle populations when planning for future coastal development.

Hypothermic Stunning in Juvenile Green Turtles (Chelonia mydas) in Uruguayan Coastal Waters: Learning for Future Events

2017 ◽  
Vol 16 (2) ◽  
pp. 151-158 ◽  
Author(s):  
Gabriela M. Vélez-Rubio ◽  
Romina Trinchin ◽  
Andrés Estrades ◽  
Virginia Ferrando ◽  
Jesús Tomás
Keyword(s):  
Coastal Waters ◽  
Chelonia Mydas ◽  
Green Turtles ◽  
Future Events

Supplemental feeding and other anthropogenic threats to green turtles (Chelonia mydas) in the Canary Islands

2018 ◽  
Vol 621 ◽  
pp. 1000-1011 ◽  
Author(s):  
Catalina Monzón-Argüello ◽  
Luis Cardona ◽  
Pascual Calabuig ◽  
María Camacho ◽  
José Luis Crespo-Picazo ◽  
...  
Keyword(s):  
Canary Islands ◽  
Chelonia Mydas ◽  
Supplemental Feeding ◽  
Green Turtles ◽  
Anthropogenic Threats

scholarly journals Satellite Tracking of Post-nesting Green Sea Turtles (Chelonia mydas) From Ras Baridi, Red Sea

2021 ◽  
Vol 8 ◽  
Author(s):  
Ahmed M. Al-Mansi ◽  
Anas Z. Sambas ◽  
Baleegh A. Abukaboos ◽  
Ahmed H. Al Zahrani ◽  
Ahmed S. Abdulaziz ◽  
...  
Keyword(s):  
Saudi Arabia ◽  
Red Sea ◽  
Chelonia Mydas ◽  
Marine Turtles ◽  
Green Turtles ◽  
The North ◽  
Nesting Site ◽  
Nesting Sites ◽  
Coastal Margin ◽  
Anthropogenic Threats

Identifying migratory pathways and linking nesting sites to foraging areas is essential for effective conservation management of migratory species, such as marine turtles. Post-nesting marine turtles disperse from their nesting sites to multiple foraging areas located from a few to hundreds of kilometers away. Over a six-year period 16 female green turtles (Chelonia mydas) were equipped with satellite transmitters between October and December of five nesting seasons to determine their migratory routes from their nesting area at five contiguous beaches at Ras Baridi, Saudi Arabia, to their foraging areas. All foraging areas for these turtles were located in shallow coastal areas or in shallow areas around offshore islands within the Red Sea basin. The majority (n = 12) migrated through the shallow (<200 m) water along the coastal margin to reach foraging areas located to the North (n = 4) and South (n = 12) of the nesting site. Four turtles crossed the deep trough of the Red Sea during their journeys. Ten of the 16 turtles migrated to foraging areas within the territorial waters of Saudi Arabia. The other six turtles migrated to foraging areas in Egypt (n = 4) and Eritrea (n = 2). These 16 turtles traveled between 130 and 1749 km from their nesting site to foraging areas located in the northern, middle and southern parts of the Red Sea. Because these turtles utilized foraging areas in at least three countries (Saudi Arabia, Egypt, and Eritrea) and one passed through the territorial waters of Sudan, conservation and management of green turtles in the Red Sea requires multinational cooperation to address anthropogenic threats in the region.

scholarly journals Effects of a power plant closure on home ranges of green turtles in an urban foraging area

2020 ◽  
Vol 41 ◽  
pp. 265-277 ◽  
Author(s):  
T Eguchi ◽  
J Bredvik ◽  
S Graham ◽  
R LeRoux ◽  
B Saunders ◽  
...  
Keyword(s):  
Power Plant ◽  
Green Turtle ◽  
Chelonia Mydas ◽  
Home Ranges ◽  
Utilization Distribution ◽  
Green Turtles ◽  
Foraging Area ◽  
San Diego Bay ◽  
Conservation Actions ◽  
Satellite Transmitters

A natural experiment was conducted to determine effects of a fossil-fueled power plant on home ranges of east Pacific green turtles Chelonia mydas in an urban foraging ground. The power plant, located in south San Diego Bay, California, USA, co-existed with a resident foraging aggregation of ~60 green turtles for ~50 yr. It was decommissioned during a long-term green turtle monitoring study, thus providing a rare opportunity to evaluate how the cessation of warm-water effluent affected turtle movements and habitat use in the area. During pre- and post-decommissioning of the power plant, 7 and 23 green turtles, respectively, were equipped with GPS-enabled satellite transmitters. Useful data were obtained from 17 turtles (4 for pre- and 13 for post-decommissioning). Core use areas (50% utilization distribution [UD]) increased from 0.71 to 1.37 km2 after the power plant decommissioning. Increase in post-power plant 50% UD was greater during nighttime (0.52 to 1.44 km2) than daytime (1.32 to 1.43 km2). Furthermore, UDs moved from the effluent channel to an area closer to seagrass pastures, a presumed foraging habitat of the turtles. The observed expansion of green turtle home ranges may increase turtle-human interactions, such as boat strikes, within the foraging ground; this underscores how seemingly innocuous human actions contribute to inadvertent consequences to wildlife. Possible management and conservation actions include increasing awareness of the public regarding turtle presence in the area through signage and education as well as legislating for a reduction in boat speeds in select areas of the bay.

scholarly journals Use of the Alaskan Beaufort Sea by Bowhead Whales (Balaena mysticetus) Tagged with Satellite Transmitters, 2006 – 18

ARCTIC ◽  
2020 ◽  
Vol 73 (3) ◽  
pp. 278-291
Author(s):  
Justin Olnes ◽  
John J. Citta ◽  
Lori T. Quakenbush ◽  
John C. George ◽  
Lois A. Harwood ◽  
...  
Keyword(s):  
Satellite Telemetry ◽  
State Space Model ◽  
Beaufort Sea ◽  
Bowhead Whale ◽  
Movement Behavior ◽  
Autumn Migration ◽  
Bowhead Whales ◽  
Dive Behavior ◽  
Satellite Transmitters ◽  
Switching State

We used satellite telemetry to examine bowhead whale movement behavior, residence times, and dive behavior in the Alaskan Beaufort Sea, 2006 – 18. We explored the timing and duration of use of three subregions (western, central, eastern) within the Alaskan Beaufort Sea and applied a two-state switching state-space model to infer bowhead whale behavior state as either transiting or lingering. Transiting whales made direct movements whereas lingering whales changed direction frequently and were presumably feeding. In spring, whales migrated across the Alaskan Beaufort Sea in 7.17 ± 0.41 days, primarily off the continental shelf over deep water. During the autumn migration, whales spent over twice as much time crossing the Alaskan Beaufort Sea than in spring, averaging 18.66 ± 2.30 days, spending 10.05 ± 1.22 days in the western subregion near Point Barrow. Most whales remained on the shelf during the autumn migration and frequently dove to the seafloor, where they spent 45% of their time regardless of behavioral state. Consistent dive behavior in autumn suggests that the whales were looking for food while migrating, and the identification of lingering locations likely reflects feeding. The lack of lingering locations in the eastern and central subregions suggests that prey densities are rarely sufficient to warrant whales pausing their migration for multiple days, unlike in the western subregion near Point Barrow, where bowhead whales regularly lingered for long periods of time.

scholarly journals Migratory corridor linking Atlantic green turtle, Chelonia mydas, nesting site on Bioko Island, Equatorial Guinea to Ghanaian foraging grounds

PLoS ONE ◽  
2019 ◽  
Vol 14 (6) ◽  
pp. e0213231 ◽  
Author(s):  
Emily Mettler ◽  
Chelsea E. Clyde-Brockway ◽  
Shaya Honarvar ◽  
Frank V. Paladino
Keyword(s):  
Green Turtle ◽  
Chelonia Mydas ◽  
Equatorial Guinea ◽  
Bioko Island ◽  
Nesting Site ◽  
Migratory Corridor

scholarly journals The diving behaviour of green turtles undertaking oceanic migration to and from Ascension Island: dive durations, dive profiles and depth distribution

2001 ◽  
Vol 204 (23) ◽  
pp. 4093-4098
Author(s):  
G. C. Hays ◽  
S. Åkesson ◽  
A. C. Broderick ◽  
F. Glen ◽  
B. J. Godley ◽  
...  
Keyword(s):  
Depth Distribution ◽  
Satellite Telemetry ◽  
Chelonia Mydas ◽  
Diving Behaviour ◽  
Near Surface ◽  
Green Turtles ◽  
Marine Reptiles ◽  
Ascension Island

SUMMARY Satellite telemetry was used to record the submergence duration of green turtles (Chelonia mydas) as they migrated from Ascension Island to Brazil (N=12 individuals) while time/depth recorders (TDRs) were used to examine the depth distribution and dive profiles of individuals returning to Ascension Island to nest after experimental displacement (N=5 individuals). Satellite telemetry revealed that most submergences were short (<5 min) but that some submergences were longer (>20 min), particularly at night. TDRs revealed that much of the time was spent conducting short (2–4 min), shallow (approximately 0.9–1.5 m) dives, consistent with predictions for optimisation of near-surface travelling, while long (typically 20–30 min), deep (typically 10–20 m) dives had a distinctive profile found in other marine reptiles. These results suggest that green turtles crossing the Atlantic do not behave invariantly, but instead alternate between periods of travelling just beneath the surface and diving deeper. These deep dives may have evolved to reduce silhouetting against the surface, which would make turtles more susceptible to visual predators such as large sharks.

Stock composition of green turtles Chelonia mydas foraging in the Ryukyu Archipelago differs with size class

2018 ◽  
Vol 600 ◽  
pp. 151-163 ◽  
Author(s):  
T Hamabata ◽  
H Nishizawa ◽  
I Kawazu ◽  
K Kameda ◽  
N Kamezaki ◽  
...  
Keyword(s):  
Chelonia Mydas ◽  
Size Class ◽  
Ryukyu Archipelago ◽  
Green Turtles
Sign in / Sign up

Export Citation Format

Share Document