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    A TWO-HEADED GREEN SEA TURTLE (Chelonia mydas) HATCHLING ON SAMANDAG BEACH, TURKEY
    (Folium Publ Co, 2017) Sonmez, Bektas; Sert, Mehmet; Kayikci, Senem; Bedirci, Ozay; Yalçın Özdilek, Şükran
    A two headed green sea turtle (Chelonia mydas) was found on Samandag Beach, Turkey in 2015 nesting season. The two heads were anatomically similar with independent reaction to external stimuli. The carapace scutes showed anomalies. Radiography was performed and the spinal column was seen to bifurcate in the area close to the caudal region. In the post mortem examination, esophagus, stomach, liver, lung, heart and trachea were duplicated. The two headed green turtle was subclassified as teratodidymus. Dicephalism rarely occurs in sea turtle and perhaps genetic factors may play a significant role for this two headed green sea turtle.
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    Comparison of the physical properties of two Green Turtle (Chelonia mydas) nesting beaches (Akyatan and Samandag) in the eastern Mediterranean (Reptilia: Cheloniidae)
    (Taylor & Francis Ltd, 2013) Sonmez, Bektas; Turan, Cemal; Yalçın Özdilek, Şükran
    The physical properities of sea turtle nesting beaches may strongly influence embryo development and hence conservation planning. In this study, we compared the characteristics of two nesting beaches of Green Turtles, Chelonia mydas, at Akyatan and Samandag in southern Turkey. A total of 48 sand samples from 48 nests was examined and compared in respect to moisture content (M), temperature (TT), electrical conductivity (EC), salinity (S), total dissolved solution (TDS), pH, air ratio (AR), sand grain size together with distance from sea (DFS), depth (ND), incubation period (ID) and hatching success. Significant differences between the two areas were found in nest chamber moisture, conductivity, salinity, total dissolved solution and sand grain size. In a principal component analysis (PCA), the first component explained 45.1% of the variability and was dominated by the effects of the TDS, EC, S, pH and M. The second component explained 24.2 % of the variation and was dominated by the contributions of the TT, ID and ND. This is evidence that moisture plays a more important role than thermal properties in differentiating between the two beaches.
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    CONSERVATION TECHNIQUE OF THE GREEN TURTLE (Chelonia mydas L. 1758) NESTS UNDER THE RISK OF TIDAL INUNDATION WITH HATCHERIES, ON SAMANDAG BEACH, TURKEY
    (Folium Publ Co, 2013) Sonmez, Bektas; Ozdilek, Sukran Talcm
    Eggs of green turtles are at risk from tidal inundation were transferred in hatcheries on Samandag during nesting season of 2004. In this study four hatcheries were constructed as well as conducting a control group for each hatchery. It was found that the hatching success in hatcheries was similar to natural nests, but it was higher than control group whereas, the number of dead hatchlings in hatcheries was higher than in natural nests. These differences might be due to temperature of nest, the mean nest temperature of hatcheries was higher, and the mean incubation duration was shorter than natural nests. The moisture content differs among nests, and control group nests have higher moisture content than the others. Even if hatcheries have higher hatching success, they have possible negative effect on viability of hatchlings in nest and natural sex ratio. More research is needed on the impacts of hatchery such as alteration of sex ratio and viability of hatchlings in nest.
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    GREEN TURTLES (Chelonia mydas) FEEDING ON INVASIVE ALGAE Caulerpa taxifolia IN TURKEY
    (Folium Publ Co, 2015) Yalçın Özdilek, Şükran; Akdeniz, Burcu; Firat, Ali Rahmi; Balkan, Emine Inci; Gursoy, Sait; Sonmez, Bektas; Erdugan, Huseyin
    An invasive species is a species that has been introduced to an area outside its natural range and can cause ecological problems such as change the functions of ecosystems. A female green turtle was predated by a jackal on Samandag beach, in Turkey. Stomach content was sampled and stored for diet analysis. Macroalgae were the dominant food in terms of mass, and Caulerpa taxifolia (M. Vahl) C. Agardh, which is an invasive species, was the most frequent food type. Although this species has not been shown to be a preferred diet item for green turtles, C. taxifolia is dominant species at the area and was consumed by the adult green turtle.
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    Mother- Hatchling Isotopic Relationship in Green Turtle: Isotopic Niche-based Modelling
    (Biodiversity Research Center, Acad Sinica, 2024) Yalçın Özdilek, Şükran; Sonmez, Bektas; Mestav, Burcu
    The isotopic discrimination between a mother and her hatchlings has been modelled in various vertebrates, including sea turtles. In addition to the linear relation between s13C and s15N isotope values of the mother - hatchling couple, there is missing data on the combined effects of both isotopes, which represent ecological niches of a species. The stable s13C and s15N isotope signatures of live hatchlings and their mother's epidermis tissues were used in green turtles. The samples were taken from three main breeding beaches, Akyatan, Sug & ouml;z & uuml; and Samanda & gbreve; in T & uuml;rkiye during the 2020 nesting season. s15N and s13C values of hatchlings were not significantly different from those of mothers. Significant relationships were found between hatchlings and their mothers in terms of s13C value. Furthermore, when the hatchling isotopic niche size is known, the condition probabilities of estimating the mother's isotopic niche size were 85.16% and 92.88% with the 0.95 and 0.99 alpha levels. In addition to showing a linear relationship between hatchlings and their mother's single isotopic composition, the current study offers a novel insight that proposes a niche overlap concept using two isotopes to comprehend the mother-hatchling relationship of green turtles living in the eastern Mediterranean.
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    Sex ratio estimations of Chelonia mydas hatchlings at Samandag Beach, Turkey
    (Tubitak Scientific & Technological Research Council Turkey, 2016) Yalçın Özdilek, Şükran; Sonmez, Bektas; Kaska, Yakup
    Samandag Beach, an important nesting location for endangered green turtles (Chelonia mydas), is located at the most eastern part of the Mediterranean in Turkey. Hatchling sex ratio can be one of the key factors for green turtle protection, which is under the threat of global climate change. In this study, sex ratios of hatchlings were estimated by histological examination of dead hatchlings (n = 190) and by nest temperatures (n = 14) at Samandag Beach between the 2003 and 2007 nesting seasons. The histological examination of dead C. mydas hatchlings and temperature-recorded nests indicated a female-biased sex ratio on Samandag Beach. By histological examination, top and bottom levels of nests were recorded as 94% and 64% of females. Sex ratios during the middle third of the incubation period ranged from 39% to 97% for females with a mean of 74%. Distance from the sea was correlated with the middle third of incubation temperature (r = -0.604, P = 0.022) and female ratio (r = -0.573, P = 0.032). While nest temperatures and nest parameters such as hatching success, clutch size, nest distance from the sea and from vegetation, nest depth, and the day of emergence were not found significantly different among years (P > 0.05), incubation duration was found significantly different among years (P < 0.05). The results showed a female-dominated sex ratio by both histology and nest temperature. The knowledge of hatchling sex ratios provides information on demographic parameters, and coupled with appropriate conservation measures this can make important contributions to studies of climate change effects on green sea turtle populations.
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    Some properties of new nesting areas of sea turtles in north-eastern Mediterranean situated on the extension of the Samanda Beach, Turkey
    (Triveni Enterprises, 2006) Yalçın Özdilek, Şükran; Sonmez, Bektas
    One of the most endangered species in tropical seas, Chelonia mydas (green turtles) prefer undisturbed sand beaches to lay their eggs. While Caretta caretta lays their eggs all over the Mediterranean beaches of Turkey, C. mydas nesting locations are limited with north-eastern site (Alata, Kazanh, Akyatan and Samandag) of the country and some beaches in Cyprus. UnN 2003, no nesting place of both species between Akyatan and Samandag was recorded. From north to south, the beaches examined in 2003 summer are Arsuz, Konaclk, Kale, Tr-H-3, Tr-H-2, and Tr-H-1 in addition to well-known and studied nesting beaches of sea turtle species in Hatay Province: Cevlik, Seyhhizir and Meydan. Since the Hatay Provincial Coast between Cevlik and Arsuz is hilly and no stabilized road is available, these small beaches were not known to have both C. mydas and C. caretta nests. Some physical and chemical sand properties, the number of nests belong to both species and selected nest specifications were investigated in this study. Kale Beach was found to be the most important nesting place in this less populated area. Based on results, Kale, Tr-H-3 and Tr-H-1 beaches were recorded to have high hatchling success.
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    Stranded sea turtle records between 2010 and 2017 in northern Aegean and Sea of Marmara
    (Elsevier Science Bv, 2018) Yalçın Özdilek, Şükran; Sonmez, Bektas; Sert, Mehmet
    Studies on sea turtles in Turkey have mostly been concentrated on nesting beaches. Although there is no sea turtle nesting beaches on the northern Aegean Sea coast, there are stranded sea turtle records from the northern Aegean Sea and the Sea of Marmara. This study aimed to investigate causes of strandings and their spatio-temporal distribution in these two seas between 2010 and 2017. For data acquisition, denunciations to the Canakkale Onsekiz Mart University's Sea Turtle Research and Application Center (COMU-DEKUM) were used. A total of 37 sea turtles were studied; 8.1% of them were Chelonia mydas, and 91.9% were Caretta caretta. The number of dead strandings (53%) was higher than that of injured strandings (47%). The mean curved carapace length and width of the 27 C. caretta individuals were 68.97 cm and 61.96 cm, respectively, and for C. mydas, these values were 34.5 cm and 29.5 cm, respectively. The most intensive area of strandings was Canakkale (76.5%). Moreover, although adult sea turtles were frequently stranded in the Sea of Marmara, sub-adult sea turtles were frequently stranded in the northern Aegean Sea. The leading causes of strandings in the study site were identified as intentional harm (45.9%) and fishing activities (27%). The results of this study show that coasts of the northern Aegean and the Sea of Marmara may be marine habitats of sea turtles. It is recommended that awareness-raising activities for fishermen in the region should be initiated. (C) 2018 Elsevier B.V. All rights reserved.
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    Strandings of loggerhead (Caretta caretta) and green (Chelonia mydas) sea turtles along the eastern Mediterranean coast of Turkey
    (British Herpetol Soc, 2013) Turkozan, Oguz; Yalçın Özdilek, Şükran; Ergene, Serap; Ucar, Askin Hasan; Sonmez, Bektas; Yilmaz, Can; Kacar, Yasemin
    Data on strandings of dead loggerhead (Caretta caretta) and green (Chelonia mydas) turtles were collected from the eastern Mediterranean coast of Turkey during the nesting seasons between 2002 and 2009. A total of 276 strandings were recorded (142 C. caretta and 128 C. mydas). The curved carapace length (CCL) of C. caretta ranged from 12.6-85 cm (mean 63.50 +/- 1.06 cm). The CCL of C. mydas ranged from 20-93 cm with a mean of 40.97 +/- 1.41 cm. 2.4% and 31.7% of the loggerheads were oceanic stage small juveniles (<= 30 cm CCL) and adults (>= 70 cm CCL), respectively. Of the green turtles, 33.3% (<= 31.5 cm CCL) and 4.6% (>= 85 cm CCL) were small juveniles and adults, respectively. The source populations of these turtles could become identified with genetic mixed stock analysis.
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    The effect of relocation on the morphology of Green Turtle, Chelonia mydas (Linnaeus, 1758), hatchlings on Samandag beach, Turkey (Reptilia: Cheloniidae)
    (Taylor & Francis Ltd, 2011) Sonmez, Bektas; Turan, Cemal; Yalçın Özdilek, Şükran
    We studied the impact of nest relocation in Green Turtles, Chelonia mydas (Linnaeus, 1758), on hatchling morphology at Samandag, Turkey, and examined 350 hatchlings taken equally from both natural nests and relocated nests. The nuchal, vertebral and costal series were the most variable and the supracaudal scutes were almost stable for the hatchlings in both groups. There were significant differences in all sets of nuchal, costal and marginal except vertebral seines between hatchlings from natural and relocated nests. Hatchlings from relocated nests also had a smaller straight carapace width and lower weight than hatchlings from natural nests. Furthermore, hatchlings from relocated nests had smaller left and right fore limb lengths than hatchlings from natural nests. There were significant differences between both nests in incubation duration and moisture content. Relocation thus has a negative effect on hatchling morphology and consequently on the fitness of hatchlings. The smaller size of hatchlings (with scute variations) results in reduced fitness. In spite of the relocation of nests being an important protection technique, it has a negative effect on the morphology and probably on the viability of hatchlings.