Geomatics approach to assess nesting habitat of green turtles Wadi El Gemal, Red Sea, Egypt

After seven years' study, visiting islands scattered over more than a million square miles of the western Indian Ocean, where once hundreds of thousands of green turtles nested every year, the author?'s “optimistic estimate” of the number of females nesting today is 5500. Only eighty years ago 12,000 were taken in one year on Aldabra alone. Over-exploitation by man for food – both of nesting females and eggs – and destruction of nesting habitat, i.e. disturbance of the beaches, are the two factors that are destroying this immensely valuable resource. The author's study was assisted by FPS.

Download Full-text

Biophysical Characteristics of Nesting Habitat of Green Turtle Chelonia mydas In the Coastal Zone of Kasiak, Bindalang and Karabak Ketek Island Of West Sumatra Indonesia

International Journal of Agricultural Sciences ◽

10.25077/ijasc.3.2.44-49.2019 ◽

2019 ◽

Vol 3 (2) ◽

pp. 44

Author(s):

Harfiandri Damanhuri ◽

Dahelmi Dahelmi ◽

Hafrijal Syandri ◽

Dietriech G. Bengen

Keyword(s):

Green Turtle ◽

Chelonia Mydas ◽

Sandy Beaches ◽

Marine Conservation ◽

Survey Method ◽

Nesting Habitat ◽

Chi Square ◽

Conservation Area ◽

Green Turtles ◽

West Sumatra

The research was conducted on three small islands of marine conservation area of West Sumatra, namely Kasiak Island, Bindalang Island and Karabak Ketek Island from January to December 2016. This research aimed to study the variation of biophysical character of nesting habitat of green turtle (Chelonia mydas L, 1758) by survey method, measurement, observation and analysis. All data were analyzed using Main Component Analysis (PCA), Kriskal Wallis Test Analysis. Based on PCA analysis, the contribution on main character is 43.28%. These results are supported by biophysical conditions of spawning habitats for green turtles is on Karabak Ketek Island as an ideal island of spawning sites favored by green turtles, when compared to the location of Bindalang Island and Kasiak Island habitats.Result of Kruscal Wallis analysis of Karabak Island rank; 11.90, with a chi-square value; 10.47, asymp sig value 0.005 (5% -10%). This value shows the difference between the biophysical character of the spawning habitat on the character of the coastal slope parameter (KP) is 9.60 °.This is also the ideal slope value for the sandy beach habitat (PSe) and fine sandy beaches (PHA) as the main spawning location for green turtles in West Sumatra

Download Full-text

Satellite Tracking Reveals Nesting Patterns, Site Fidelity, and Potential Impacts of Warming on Major Green Turtle Rookeries in the Red Sea

Frontiers in Marine Science ◽

10.3389/fmars.2021.633814 ◽

2021 ◽

Vol 8 ◽

Author(s):

Takahiro Shimada ◽

Carlos M. Duarte ◽

Abdulaziz M. Al-Suwailem ◽

Lyndsey K. Tanabe ◽

Mark G. Meekan

Keyword(s):

Success Rate ◽

Red Sea ◽

Land Surface ◽

Census Data ◽

Chelonia Mydas ◽

Nesting Success ◽

Conservation Strategy ◽

Green Turtles ◽

The Mean ◽

Nesting Patterns

Major aggregations of nesting green turtles (Chelonia mydas) occur in the northern Red Sea, although little is known about the reproductive ecology of this endangered species in the region. To address this issue, we satellite-tracked 30 female green turtles to document their movements and to identify factors driving habitat use at two major rookeries in the Red Sea, Jazirat Mashabah (Mashabah Island) and Ras Al Baridi in Saudi Arabia. Between successive nesting events, turtles displayed high fidelity to nesting beaches and adjacent in-water habitats (inter-nesting habitats). Using generalized linear mixed models, we estimated the mean probability of nesting per beach emergence (nesting success rate) to be 0.628, and the mean duration between a successful nesting event and the successive emergence onto the beach (re-nesting interval) to be 10.8 days at each site. The nesting success rate was relatively high (>0.8) when the preceding daytime land surface temperature (LST) was lower than 37°C but decreased with elevated daytime LST (<0.4 when >47°C). Re-nesting interval was longer at lower water temperatures and towards the end of the nesting season of individuals. Our study improves the robustness of abundance estimates from census data (e.g., track counts) and shows that the protection of nesting and inter-nesting habitats during a breeding season would be an effective conservation strategy for the species. We discuss how global warming could increase energy expenditure due to lowered nesting success, ultimately compromising the reproductive fitness of these populations.

Download Full-text

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

Frontiers in Marine Science ◽

10.3389/fmars.2021.758592 ◽

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.

Download Full-text