MTN 131:46-47 Morphologic Characters of Albino Green Turtle (Chelonia mydas) Hatchlings on Samandağ Beach in Turkey

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Morphologic Characters of Albino Green Turtle (Chelonia mydas) Hatchlings on Samandağ Beach in Turkey

Bektaş Sönmez¹ & Şükran Yalçın Özdilek²
¹Çanakkale Onsekiz Mart University Sea Turtle Research and Application Centre, Samandağ Governor Scientific Research Centre, Samandağ, Hatay, Turkey (E-mail: bektass@gmail.com);
²Canakkale Onsekiz Mart University Faculty of Science and Arts, Department of Biology, Ecology Division, Terzioglu Campus 17100 Canakkale, Turkey (E-mail: yalcin.ozdilek@gmail.com)

The green turtle (Chelonia mydas L. 1758) regularly occurs in the Mediterranean, nesting along the coasts of Greece, Northern Cyprus and Turkey (Kasparek et al. 2001). Previous studies indicate that Samandağ Beach (36°7.500’N 35°55.100’E) is an important nesting site for green turtles (Yalçın Özdilek 2007). Common abnormalities in sea turtles include super- and sub-numerary scutes, lack of color, head and jaw abnormalities, and twinning (Türkozan & Durmuş 2001). The lack of normal skin and shell pigmentation of hatchlings (often referred to as albinism) is a recessively inherited trait. Albino hatchlings are thought to have reduced survival in the wild (Türkozan & Durmus 2001). In Northern Cyprus and the southwest Turkey, nearly 1% of the embryos/hatchlings examined exhibited albinism (Kaska & Downie 1999). Albinism in sea turtles has been reported in the Mediterranean and elsewhere (Marcovaldi 1995; Türkozan & Durmuş 2001). However, few if any published data are available concerning size and scale patterns of live albino turtles. This study presents the first morphological measures of living albino green turtle hatchlings from the Northern Mediterranean.

The data were collected on Samandag Beach during the nesting season in 2010. After hatchling emergence, nest chambers were excavated in order to detect clutch size, nest depth, nest diameter and compressed hatchlings. Albinos were encountered in the nests during these excavations. Measures of straight carapace length (SCL), straight carapace width (SCW), curved carapace length (CCL), curved carapace width (CCW), fore limb length (FLL) from both left and right, hind limb length (HLL) from both left and right, weight, and scute patterns were compared with the previous records (Bolten 1999, Türkozan et al. 2001, Özdemir & Türkozan 2006). Manual calipers (±0.1 mm), and manual scales (± 1g with Pesola scale) were used for measurements.

Figure 1. Live albino green sea turtle hatchlings found on Samandağ beach, Turkey.

We found two live albino turtles during the nest excavations (Figure 1); they were released into the sea after being examined in the laboratory. The nest in which albinos were found contained 165 eggs with a hatch rate of 63.6%. This nest contained 60 undeveloped eggs and incubation period was 56 days. The nest was 75 cm in depth and 28 cm in diameter, 65 m far from the high tide line. The rate of carapace scute abnormalities was high (Table1). Vertebral and costal scutes distributions were different compared to common (normal) scute patterns (see Table 1 in Türkozan et al. 2001). The morphometric characteristics of the albino hatchlings (Table 2) were normal in Samandağ Beach. However, the size of the albinos was greater than the mean of non-albino hatchlings on Samandag beach (Sönmez 2010).

Table 1. Frequency of carapace scute patterns in green turtle albino hatchlings from Turkey.

Other records of albinism in hatchlings have been recorded in Malaysia and Florida and Brazil for green and loggerhead turtles (Harrisson 1963; Fletemeyer 1977; Marcovaldi 1995 in Türkozan & Durmuş 2001). However reports of juvenile or adult live albino turtles in the wild are rare: one albino juvenile green sea turtle was reported from Florida, weighing 56 kg (Fletemeyer 1977 in Türkozan & Durmuş, 2001), and a white adult loggerhead was seen nesting in Australia (Limpus 1979).

Table 2. Descriptive measures of the morphometric variables of live albino green turtle hatchlings from Turkey. SCL/SCW=straigtht carapace length/width in cm, CCL/CCW=curved carapaced length/width in cm, LFLL/RFLL=left and right fore limb length in cm, LHLL/RHLL=left and right hind limb length, and mass is in g.

Scute abnormalities are more commonly observed in albino hatchlings than in normally colored turtles (Kaska & Downie 1999). Hatchling morphology can determine the survival rate in sea turtle (Özdemir et al. 2007). Generally, bigger hatchlings are faster swimmers and are thought to be more likely to escape from predators (Burges et al. 2006). A larger body size may also help hatchlings to escape gape-limited predators and to handle larger prey items successfully, i.e. bigger is better. It may be the case that the albinos we observed have a better advantage to survive in the wild than their smaller counterparts. However, they also likely have some disadvantages, including reduced crypsis and potentially more susceptibility to solar radiation.

Acknowledgements: We thank to Samandağ Governor, Hatay Directorate of Environmental Ministry and Natural Parks and Nature Protect Division. We also thank to Sait Gürsoy and K. Mehmet Ali Sönmez and many other volunteer students.

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