The value of long-term, community-based monitoring of marine turtle nesting: a study in the Lamu archipelago, Kenya

AbstractMonitoring of nesting beaches is often the only feasible and low-cost approach for assessing sea turtle populations. We investigated spatio-temporal patterns of sea turtle nesting activity monitored over 17 successive years in the Lamu archipelago, Kenya. Community-based patrols were conducted on 26 stretches of beach clustered in five major locations. A total of 2,021 nests were recorded: 1,971 (97.5%) green turtleChelonia mydasnests, 31 (1.5%) hawksbillEretmochelys imbricatanests, 8 (0.4%) olive ridleyLepidochelys olivaceanests and 11 (0.5%) unidentified nests. Nesting occurred year-round, increasing during March–July, when 74% of nests were recorded. A stable trend in mean annual nesting densities was observed in all locations. Mean clutch sizes were 117.7 ± SE 1 eggs (range 20–189) for green turtles, 103±SE 6 eggs (range 37–150) for hawksbill turtles, and 103±SE 6 eggs (range 80–133) for olive ridley turtles. Curved carapace length for green turtles was 65–125 cm, and mean annual incubation duration was 55.5±SE 0.05 days. The mean incubation duration for green turtle nests differed significantly between months and seasons but not locations. The hatching success (pooled data) was 81.3% (n = 1,841) and was higher for in situ nests (81.0±SE 1.5%) compared to relocated nests (77.8±SE 1.4%). The results highlight the important contribution of community-based monitoring in Kenya to sustaining the sea turtle populations of the Western Indian Ocean region.

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Status and community-based conservation of marine turtles in the northern Querimbas Islands (Mozambique)

Oryx ◽

10.1017/s0030605311001566 ◽

2012 ◽

Vol 46 (3) ◽

pp. 359-367 ◽

Cited By ~ 22

Author(s):

Julie Garnier ◽

Nicholas Hill ◽

Almeida Guissamulo ◽

Isabel Silva ◽

Matthew Witt ◽

...

Keyword(s):

Local Community ◽

Regional Cooperation ◽

Western Indian Ocean ◽

Chelonia Mydas ◽

Marine Conservation ◽

Marine Turtle ◽

Community Based ◽

East African Coast ◽

North West ◽

Green Turtles

AbstractSituated in the northernmost part of Mozambique, the northern Querimbas Islands support some of the most diverse and pristine coral reefs in the Western Indian Ocean. The community-based turtle conservation programme that we developed on Vamizi Island has facilitated the identification and protection of a key nesting site for the green marine turtle Chelonia mydas in Mozambique, with a mean of 122 nests per year. The area is also used by nesting female and immature hawksbill turtles Eretmochelys imbricata. Nesting activity of green turtles was observed all year round, with a peak in the summer (February–March). Incubation periods of this species showed seasonal fluctuations inversely correlated with air temperature. Hatching success was high (87%) when nests were not lost through tidal overwash and erosion, which affected nearly 40% of all nests in 2007. Using satellite tracking of four green turtles nesting on Vamizi we identified foraging grounds in marine protected areas in Kenya, Tanzania and north-west Madagascar. Migratory routes of two individuals along the East African coast were generally neritic and all passed through the waters of multiple nations and as many as six marine conservation areas, emphasizing the importance of regional cooperation. Awareness programmes were also conducted with resource users, and the development of a community-based management system triggered the creation of a marine sanctuary by the local community.

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Dietary analysis of two sympatric marine turtle species in the eastern Mediterranean

Marine Biology ◽

10.1007/s00227-021-03895-y ◽

2021 ◽

Vol 168 (6) ◽

Author(s):

Josie L. Palmer ◽

Damla Beton ◽

Burak A. Çiçek ◽

Sophie Davey ◽

Emily M. Duncan ◽

...

Keyword(s):

Green Turtle ◽

Eastern Mediterranean ◽

Chelonia Mydas ◽

Marine Turtle ◽

Dietary Analysis ◽

Low Frequencies ◽

Turtle Species ◽

Dietary Shift ◽

Green Turtles ◽

Loggerhead Turtles

AbstractDietary studies provide key insights into threats and changes within ecosystems and subsequent impacts on focal species. Diet is particularly challenging to study within marine environments and therefore is often poorly understood. Here, we examined the diet of stranded and bycaught loggerhead (Caretta caretta) and green turtles (Chelonia mydas) in North Cyprus (35.33° N, 33.47° E) between 2011 and 2019. A total of 129 taxa were recorded in the diet of loggerhead turtles (n = 45), which were predominantly carnivorous (on average 72.1% of dietary biomass), foraging on a large variety of invertebrates, macroalgae, seagrasses and bony fish in low frequencies. Despite this opportunistic foraging strategy, one species was particularly dominant, the sponge Chondrosia reniformis (21.5%). Consumption of this sponge decreased with increasing turtle size. A greater degree of herbivory was found in green turtles (n = 40) which predominantly consumed seagrasses and macroalgae (88.8%) with a total of 101 taxa recorded. The most dominant species was a Lessepsian invasive seagrass, Halophila stipulacea (31.1%). This is the highest percentage recorded for this species in green turtle diet in the Mediterranean thus far. With increasing turtle size, the percentage of seagrass consumed increased with a concomitant decrease in macroalgae. Seagrass was consumed year-round. Omnivory occurred in all green turtle size classes but reduced in larger turtles (> 75 cm CCL) suggesting a slow ontogenetic dietary shift. Macroplastic ingestion was more common in green (31.6% of individuals) than loggerhead turtles (5.7%). This study provides the most complete dietary list for marine turtles in the eastern Mediterranean.

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ASPEK MORFOLOGI, REPRODUKSI, DAN PERILAKU PENYU HIJAU (Chelonia mydas) Di PANTAI PANGUMBAHAN, KABUPATEN SUKABUMI, JAWA BARAT

BAWAL Widya Riset Perikanan Tangkap ◽

10.15578/bawal.3.2.2010.93-101 ◽

2017 ◽

Vol 3 (2) ◽

pp. 93

Author(s):

Adriani Sri Nastiti Krismono ◽

Achmad Fitriyanto ◽

Ngurah Nyoman Wiadnyana

Keyword(s):

Green Turtle ◽

Carapace Width ◽

Chelonia Mydas ◽

Sea Turtle ◽

Stratified Sampling ◽

Hatching Rate ◽

Brood Stock ◽

Green Turtles ◽

And Behavior ◽

Nesting Season

Penyu hijau (Chelonia mydas) termasuk dalam phylum Chordata dan famili Cheloniideae. Jumlah penyu hijau yang singgah ke Pantai Pangumbahan untuk bertelur semakin menurun karena tidak terkendalinya masyarakat melakukan penangkapan induk penyu dan pengambilan telurnya. Penelitian tentang morfologi, reproduksi, dan perilaku penyu hijau sebagai salah satu dasar pengelolaan telah dilakukan di Pantai Pangumbahan pada bulan Agustus 2008. Metode penelitian yang digunakan pengambilan contoh berstrata. Penelitian ini dilaksanakan pada bulan Agustus 2008 (pada saat puncak peneluran). Parameter yang diamati antara lain ukuran penyu dari 89 ekor jumlah penyu bersarang, jumlah telur dan tingkat penetasan, serta perilaku pada saat penyu bertelur. Hasil penelitian menunjukan yang diamati diperoleh panjang karapas berkisar antara 97-15 cm dan lebar karapas 83,5-108 cm, jumlah penyu naik ke pantai 89 ekor dan penyu yang bertelur 39 ekor. Jumlah telur penyu hijau berhasil dihitung 80-105 butir per induk penyu. Bulan Agustus 2008 merupakan puncak musim peneluran. Kegiatan peneluran penyu hijau dibagi menjadi enam tahap. Upaya konservasi yang sudah dilakukan adalah penetasan telur penyu semi alami, restocking tukik, dan menjaga keamanan sarang telur penyu. Green turtles (Chelonia mydas), including the phylum Chordata and families Cheloniideae. The number of green turtles come to lay eggs Pangumbahan beach to decline because of increasingly unmanageable public do making arrests turtles brood stock and their eggs. Research on the morphology, reproduction, and behavior of green turtles as one of the basic management has been conducted on the Pangumbahan Beach in August 2008. The method used stratified sampling. The experiment was conducted in August 2008 (at the peak of nesting). Other parameters were observed between the size of the 89 tail number of turtles nesting turtles, the number of eggs and hatching rate and behavior during turtle nesting. Results obtained showed that the observed length ranges from 97- 15 cm carapace and carapace width from 83.5-108 cm, the number went up to the beach 89 sea turtle and sea turtle nesting tail as much as 39 tails. The number of green turtle eggs had counted as many as 80-105 eggs per turtles brood stock. Month August 2008 is the peak nesting season of green turtle nesting activities are divided into six stages. Conservation efforts that have been done is semi natural turtle hatchery, restocking hatchlings, and nest of turtle eggs to maintain security.

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Incubation temperatures, hatching success and congenital anomalies in green turtle nests from Guanahacabibes Peninsula, Cuba

AQUATIC RESEARCH ◽

10.3153/ar21027 ◽

2021 ◽

Vol 4 (4) ◽

pp. 321-330

Author(s):

Randy Calderón Peña ◽

Julia Azanza Ricardo

Keyword(s):

Congenital Anomalies ◽

Green Turtle ◽

Thermal Tolerance ◽

Elevated Temperatures ◽

Hatching Success ◽

Incubation Temperature ◽

Chelonia Mydas ◽

Sea Turtle ◽

Green Turtles ◽

Incubation Temperatures

Elevated incubation temperatures of sea turtle nests decrease hatching success and alter the resulting hatchlings' morphology. There is an absence of studies assessing the relationships between temperature and hatching success in Cuba, even when they could improve understanding the limits of thermal tolerance in these species. This study evaluated the influence of incubation temperature on hatching success and phenotypic malformations in green turtle hatchlings (Chelonia mydas); and analyzed the temporal variation in hatching success on the studied beaches. In 48 green turtles nests distributed along two beaches, incubation temperature and hatching success were recorded between 2014 and 2019. Increasing incubation temperature caused a decrease in the hatching success and an increase in the frequency of supernumerary scutes. Despite the elevated temperatures (average > 30°C), hatching was higher than 80%. Significant differences in hatching success were only observed among seasons for nests in Antonio Beach (lower values in 2016 and 2019 compared to 2014).

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Seafinding By Hatchling Sea Turtles: Role of Brightness, Silhouette and Beach Slope as Orientation Cues

Behaviour ◽

10.1163/156853992x00309 ◽

1992 ◽

Vol 122 (1-2) ◽

pp. 56-77 ◽

Cited By ~ 41

Author(s):

Mark Lucas ◽

Michael Salmon ◽

Elizabeth Fritz ◽

Jeanette Wyneken

Keyword(s):

Green Turtle ◽

Visual Cues ◽

Chelonia Mydas ◽

Sea Turtle ◽

Infrared Light ◽

Beach Slope ◽

Green Turtles ◽

Nest Sites ◽

Orientation Cues

AbstractUpon emerging from underground nests, sea turtle hatchlings immediately crawl toward the ocean. The primary cues used in orientation are visual but the nature of the visual cues was a matter of speculation. Hatchlings might also respond to secondary cues, such as beach slope. Experiments were carried out in an arena where specific visual and slope cues, simulating those present at nest sites, could be precisely controlled and manipulated. Subjects were green turtle (Chelonia mydas L.) and loggerhead (Caretta caretta L.) hatchlings. Both species oriented toward the more intensely illuminated sections of the arena. They also oriented away from dark silhouettes which simulated an elevated horizon, typical of the view toward land. Turtles responded primarily to stimuli (both silhouettes and photic differences) at or near eye level. When presented simultaneously with a silhouette and a photic gradient located in different directions, hatchlings oriented away from the silhouette and ignored photic stimuli. Under infrared light, both species oriented down slopes. However in the presence of nocturnal levels of visible light loggerheads ignored slope cues and responses of green turtles to slope were weakened. The data suggest that loggerhead and green turtle hatchlings usually find the sea by orienting away from elevated silhouettes. This is a prominent and reliable cue for species which typically nest on continental beaches.

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Use of Baculovirus-Expressed Glycoprotein H in an Enzyme-Linked Immunosorbent Assay Developed To Assess Exposure to Chelonid Fibropapillomatosis-Associated Herpesvirus and Its Relationship to the Prevalence of Fibropapillomatosis in Sea Turtles

Clinical and Vaccine Immunology ◽

10.1128/cvi.00438-07 ◽

2008 ◽

Vol 15 (5) ◽

pp. 843-851 ◽

Cited By ~ 18

Author(s):

Lawrence H. Herbst ◽

Shefali Lemaire ◽

Ada R. Ene ◽

David J. Heslin ◽

Llewellyn M. Ehrhart ◽

...

Keyword(s):

Immunosorbent Assay ◽

Recombinant Baculovirus ◽

Chelonia Mydas ◽

Sea Turtle ◽

Marine Turtle ◽

Enzyme Linked Immunosorbent Assay ◽

Green Turtles ◽

Glycoprotein H ◽

History Of ◽

Experimentally Induced

ABSTRACT Chelonid fibropapillomatosis-associated herpesvirus (CFPHV) is an alphaherpesvirus believed to cause marine turtle fibropapillomatosis (FP). A serodiagnostic assay was developed for monitoring sea turtle populations for CFPHV exposure. CFPHV glycoprotein H (gH) expressed in recombinant baculovirus was used in an enzyme-linked immunosorbent assay (ELISA) to detect virus-specific 7S turtle antibodies. Using captive-reared green turtles (Chelonia mydas) with no history of virus exposure as “known negatives” and others with experimentally induced FP as “known positives,” the assay had 100% specificity but low sensitivity, as seroconversion was detected in only half of the turtles bearing experimentally induced tumors. Antibodies were detected only in samples collected after cutaneous fibropapillomas appeared, consistent with observations that tumors are significant sites of virion production and antigen expression and the possibility that prolonged/repeated virus shedding may be required for adequate stimulation of 7S antibody responses to gH. Natural routes of infection, however, may produce higher seroconversion rates. High gH antibody seroprevalences (∼80%) were found among wild green turtles in three Florida localities with different FP prevalences, including one site with no history of FP. In addition, all eight loggerhead turtles (Caretta caretta) tested were seropositive despite FP being uncommon in this species. The possibility that CFPHV infection may be common relative to disease suggests roles for environmental and host factors as modulators of disease expression. Alternatively, the possibility of other antigenically similar herpesviruses present in wild populations cannot be excluded, although antibody cross-reactivity with the lung/eye/trachea disease-associated herpesvirus was ruled out in this study.

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Orientation to Oceanic Waves by Green Turtle Hatchlings

Journal of Experimental Biology ◽

10.1242/jeb.171.1.1 ◽

1992 ◽

Vol 171 (1) ◽

pp. 1-13 ◽

Cited By ~ 1

Author(s):

KENNETH J. LOHMANN ◽

CATHERINE M. FITTINGHOFF LOHMANN

Keyword(s):

Green Turtle ◽

Weather Conditions ◽

Chelonia Mydas ◽

Sea Turtle ◽

Wave Direction ◽

Physiological Mechanisms ◽

Wave Propagation Direction ◽

Green Turtles ◽

Open Sea ◽

Vertical Accelerations

Minutes after emerging from underground nests, hatchling green turtles (Chelonia mydas L.) enter the sea and begin a migration towards the open ocean. To test the hypothesis that migrating hatchlings use wave cues to maintain their seaward headings, we released turtles offshore during unusual weather conditions when waves moved in atypical directions. Hatchlings swam into approaching waves in all experiments, even when doing so resulted in orientation back towards land. These data suggest that green turtle hatchlings normally maintain seaward headings early in the offshore migration by using wave propagation direction as an orientation cue. Because waves and swells reliably move towards shore in shallow coastal areas, swimming into waves usually results in movement towards the open sea. The physiological mechanisms that underlie wave detection by sea turtle hatchlings are not known. Calculations indicate that, at the depth at which hatchlings swim, accelerations produced beneath typical waves and swells along the Florida coast are sufficient to be detected by the vertebrate inner ear. We therefore hypothesize that hatchlings determine wave direction while under water by monitoring the sequence of horizontal and vertical accelerations that occur as waves pass above.

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Citizen-Sourced Sightings and Underwater Photography Reveal Novel Insights About Green Sea Turtle Distribution and Ecology in Southern California

Frontiers in Marine Science ◽

10.3389/fmars.2021.671061 ◽

2021 ◽

Vol 8 ◽

Author(s):

Megan E. Hanna ◽

Erin M. Chandler ◽

Brice X. Semmens ◽

Tomoharu Eguchi ◽

Garrett E. Lemons ◽

...

Keyword(s):

Public Relations ◽

Green Turtle ◽

Southern California ◽

Chelonia Mydas ◽

Sea Turtle ◽

Green Turtles ◽

Underwater Photography ◽

Local Aggregation ◽

Distribution And Ecology ◽

La Jolla

East Pacific (EP) green turtles (Chelonia mydas) have undergone substantial population recovery over the last two decades owing to holistic protection at nesting beaches and foraging areas. At the northern end of their range in southern California United States, green turtles have been seen in more areas and in greater numbers since 2014 than before as a result. A resident population of green turtles has established near La Jolla Shores (LJS), a protected site with daily marine tourism (e.g., kayakers, snorkelers, divers). To study this local aggregation, innovative and non-invasive methods were required because the traditional capture-recapture methods were infeasible due to public relations sensitivities. Green turtle habituation to humans at this site has created a unique opportunity for citizen-based science using underwater photography to document turtles and their surroundings. We obtained 309 usable photographs of local green turtles from members of the dive/snorkel community in LJS. Photos were taken from April 2016 to June 2019. Images were processed in Hotspotter—a patterned species instance recognition software—to identify seven individuals, five of which were consistently photographed throughout that period. These images helped infer minimum residency duration (MRD), seasonal differences in algal coverage on the carapace, habitat association, behavioral patterns, and diet. Mean MRD was 424 days (SE = 131 days, calculated from entire population, n = 7), during which turtles were active in 82.8% of the photographs; the remainder of the photographs depicted foraging (14.9%) or resting behavior (2.3%). Green turtles were seen foraging in water temperatures as low as 15.8°C, the lowest recorded temperature for foraging green turtles documented in literature. Additional opportunistic observational platforms were used to look at trends of increasing green turtle abundance in southern California since 2015 that supported the arrival of a new aggregation of green turtles in LJS. Our use of citizen-sourced photographs confirms the presence of a resident aggregation of green turtles in LJS. Existence of green turtles and other protected species in highly populated areas provide excellent opportunities to educate beachgoers and seafarers about conservation of these species. This study also highlights the value of citizen-based science in areas where traditional research techniques are ill-suited.

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Low male production at the world’s largest green turtle rookery

Marine Ecology Progress Series ◽

10.3354/meps13500 ◽

2020 ◽

Vol 653 ◽

pp. 181-190

Author(s):

DT Booth ◽

A Dunstan ◽

I Bell ◽

R Reina ◽

J Tedeschi

Keyword(s):

Green Turtle ◽

Hatching Success ◽

Incubation Temperature ◽

Chelonia Mydas ◽

Sea Turtle ◽

Green Turtles ◽

Nesting Site ◽

Almost All ◽

Monthly Variations ◽

Nesting Season

Because the sex of all sea turtle hatchlings is determined by incubation temperature, with low temperatures producing mainly males and high temperatures producing mainly females, sea turtle populations worldwide are threatened by feminization of hatchlings due to increases in global temperature. Data obtained by laparoscopic sexing of immature individuals captured from a major feeding ground indicates that over several decades there has been little recruitment of males into the northern Great Barrier Reef (nGBR) green turtle Chelonia mydas population, one of the largest sea turtle populations in the world. Over 2 nesting seasons, we measured nest temperatures at Raine Island, the most important nesting site for this nGBR population, and predicted that almost all nests would have produced all female hatchlings. The few nests that produced some male hatchlings were constructed at the very end of the nesting season, and these nests had the lowest hatching success. Taking into account monthly variations in nest construction, hatching success, and hatchling sex ratio, we estimate that over an entire nesting season only 0.7% of hatchlings produced are male. Hence, we conclude that the nGBR population of green turtles has likely recruited very few males in recent years.

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DNA BARCODE ANALYSIS OF THE ENDANGERED GREEN TURTLE (Chelonia mydas) IN MEXICO

Genome ◽

10.1139/gen-2019-0213 ◽

2021 ◽

Author(s):

Fátima Yedith Camacho-Sánchez ◽

A. Alonso Aguirre ◽

Jose Alberto Narvaez-Zapata ◽

Alan A. Zavala-Norzagaray ◽

Cesar P Ley-Quiñónez ◽

...

Keyword(s):

Green Turtle ◽

Dna Barcode ◽

Chelonia Mydas ◽

Sea Turtle ◽

Population Diversity ◽

Coi Gene ◽

Dna Barcodes ◽

Mexican Pacific ◽

Turtle Species ◽

Green Turtles

Technological and analytical advances to study evolutionary biology, ecology, and conservation of green turtles (Chelonia mydas) are realized through molecular approaches including DNA barcoding. We characterized the usefulness of COI DNA barcodes in green turtles in Mexico to better understand genetic divergence and other genetic parameters of this species. We analyzed 63 sequences, 25 from green turtle field specimens collected from the Gulf of Mexico and from the Mexican Pacific, and 38 already present in the Barcode of Life Data Systems (BOLD). A total of 13 haplotypes were identified with 4 novel haplotypes from the Pacific Ocean and 3 novel haplotypes from the Atlantic Ocean. Intraspecific distance values among COI gene sequences by two different models were 0.01, demonstrating that there is not a subdivision for green turtle species. Otherwise, the interspecific distance interval ranged from 0.07 to 0.13 supporting a clear subdivision among all sea turtle species. Haplotype and total nucleotide diversity values of the COI gene reflect a medium genetic diversity average. Green turtles of the Mexican Pacific showed common haplotypes to some Australian and Chinese turtles, but different from the haplotypes of the Mexican Atlantic. COI analysis revealed new haplotypes and confirmed that DNA barcodes were useful for evaluation of the population diversity of green turtles in Mexico.

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