seaturtle.org : MTN : ARCHIVES : Sign In

Davultepe is located between Kandak Stream (36°43’44.6” N, 34°30’33.6” E) in the northeast and Onur Resort (36°42’53.5” N, 34°28’41.0” E) in the southwest of Mersin, totals 2.8 km in length, and includes Davultepe public beach, the picnic area and Gümüşkum Natural Park. The Gümüşkum Natural Park, designated on 7 November 2011, is 1.8 km long and located between Kandak Stream in the northeast and Kuğu Resort (36°43’00.8” N, 34°29’29.0” E) in the southwest. It is administered by Mersin Sea Turtle Rescue, Rehabilitation and Information Center in Gümüşkum Natural Park of Davultepe 100. Yıl Beach, and the Republic of Turkey Ministry of Forestry and Water Affairs, 7^th Regional Directorate, Section of Mersin. The basic threats facing sea turtles and their nests at Davultepe are human impacts, including boardwalks constructed along the coast, light pollution, sand removal, and predation.

Figure 1. The important nesting areas of Turkey, including Davultepe beach (underlined in orange).

The populations of green and loggerhead sea turtles nesting on Davultepe Beach was investigated over 6 nesting seasons (2009-2014). In the 2009, 2010 and 2011 nesting seasons, the study area was limited to the 1.8 km of beach in the natural park, and in 2012, 2013 and 2014 we surveyed an additional 1 km section ending at the Onur Resort. All field observations were conducted between July and October and data were collected by teams of 5 or 6 people (researchers and students). Surveys were conducted daily, in the early morning, to find the tracks made by turtles the previous evening. During patrols, all nesting and non-nesting emergences, nest predation, and hatchling emergences were investigated and recorded. Each track was examined in detail to determine whether or not there was a nest. If there was no nest, it was recorded as a “non-nesting emergence.” Nest locations were recorded and measurements were taken. All observed nests were protected against predation with wire cages that included warning signs, and coordinates were taken by means of a Global Positioning System (GPS). Then all turtle tracks in the area were obscured so they were not counted twice. The nests were excavated one week after the first emergence of hatchlings. The total number of eggs was calculated by counting unhatched eggs and hatched shell fragments. Davultepe, with a predominantly green turtle population and intensive public beach use, had some nests that were lost due to human activity or which had only empty shells and whose late embryos could not be seen; these were originally classified as “possible green turtle nests.” Possible nests were later classified as either green of loggerhead turtle nests, based on further information including the nest distance from the sea, depth, proximity to vegetation, and the experience of the researchers.

Observed nest numbers increased from 2009 to 2012 and decreased in 2013 and 2014 (Table 1). Researchers also determined the most suitable nesting area, which was the better protected and more sheltered 1.8 km beach at the Gümüşkum Natural Park of Davultepe (Table 1).

Table 1. Sea turtle nests and hatchlings reaching the sea on Davultepe Beach between 2009-2014. Sources of data: ^aErgene et al. (2010); ^bErgene et al. (2012a,b); ^cErgene (2014); ^dthis study. *Does not include two nests found outside study area (see text).

The full 2.8-km study area was surveyed in the 2012, 2013 and 2014 nesting seasons and on the 1-km section which was outside the western border of the Gümüşkum Natural Park of Davultepe, a total of 61 nests (24 nests in 2012; 24 nests in 2013 and 13 nests in 2014) were recorded, with an annual mean of 20.3 nests (Table 1). Therefore, if the full, 2.8-km study area had been surveyed in the 2009, 2010 and 2011 nesting seasons, the total number of observed nests would likely have been higher.

A total of 632 green turtle nests were recorded. Excluding the unhatched nests and some nests whose locations were lost without excavating due to intense public beach use, we calculated that 43,309 green turtle hatchlings reached the sea from 509 nests (39 nests in 2009; 49 nests in 2010; 83 nests in 2011; 150 nests in 2012; 114 nests in 2013 and 74 nests in 2014; see Table 1). We calculated that 1,668 loggerhead hatchlings reached the sea from 29 nests recorded and excavated during six consecutive nesting seasons (2009–2014) on Davultepe (Table 1). The highest number of hatchlings reaching the sea occurred in 2012, the year with the highest nest numbers (Table 1). Also in 2012, two sea turtle nests were discovered on the beach in front of the summer buildings, outside the western border of Davultepe. Locations of those two nests were lost without determining their species due to intense public beach use. These two nests were not included to the calculation of nests/km because they were outside the borders of the beach studied. Several other nests were found outside the borders of the beach by the research team after they were informed by people, but are not reported here.

Casale & Margaritoulis (2010) estimated the average number of loggerhead nests laid annually in the entire Mediterranean was 7,200 nests. Türkozan & Kaska (2010) estimated the annual number of loggerhead nests in Turkey was 769-3521, similar to the earlier estimate of 1,366 loggerhead nests/season in Turkey by Margaritoulis et al. (2003). We recorded between 2 - 11 loggerhead nests per season on Davultepe, with an annual mean of 4.8 nests, during six consecutive nesting seasons (2009–2014). On Davultepe, the number of loggerhead nests is low.

We observed between 68 - 172 green turtle nests annually during six consecutive nesting seasons (2009–2014) on Davultepe, with an annual mean of 105.3. The highest number of green turtle nests on Davultepe occurred in 2012, with 172 nests recorded in the 2.8 km-beach sector. This corresponds to a density of 61.43 nests/km, which compares favorably to the other important nesting beaches for green turtles on the East Mediterranean coasts of Turkey; Davultepe ranks fifth (Table 2).

Table 2. Comparison of the important nesting areas for Chelonia mydas on the eastern Mediterranean coasts of Turkey. ^aAureggi et al. (2000); Kasparek et al. (2001); ^bSönmez (2013) ^cErgene et al. (2012c); ^dCanbolat et al. (2005); ^eErgene et al. (2013); ^fErgene et al. (2012a,b); Ergene (2014); this study.

Estimates of the total number of green turtle nests laid in Turkey vary. Kasparek et al. (2001) estimated the annual number of green turtle nests in the Mediterranean as 350 - 1750. Canbolat (2004) estimated that the mean annual number of green turtle nests laid the coast of Turkey was 647.6, varying between 391 and 910 while Kaska et al. (2005) reported 700 - 1150 green turtle nests being laid each year in Turkey. Subsequently, Türkozan & Kaska (2010) estimated the annual green turtle nests laid on the beaches of Turkey between 452-2051. Using the values of Türkozan & Kaska (2010), the maximum and minimum nesting numbers on Davultepe constituted 15% and 8.4% of the recorded range of total nests along the Turkish coast (Table 3). The nesting numbers on Davultepe are also in proportion to the range of numbers of total nests on the Turkish coasts in Canbolat (2004), Kaska et al. (2005) and those in the Mediterranean in Kasparek et al. (2001) (Table 3).

Table 3. The proportion of minimum and maximum nest numbers on Davultepe beach between 2009-2014 to the range of annual nest numbers given for Turkey and the Mediterranean. Data sources: ^aCanbolat (2004); ^bKaska et al. (2005); ^cTürkozan & Kaska (2010); ^dKasparek et al. (2001); ^eErgene et al. (2010; 2012a,b); Ergene (2014); this study.

Casale & Margaritoulis (2010) defined any nesting beach in the Mediterranean containing > 40 nests as a major nesting site for green sea turtles. On Akyatan Beach in Beach, the average annual number of nests (362) constituted approximately 25% of the overall nesting in the Mediterranean between the 2006 and 2011 nesting seasons (Yılmaz et al. 2015). During six consecutive nesting seasons (2009 – 2014), green turtle nests at Davultepe (mean = 105.3 nests/year) constituted 7% of the green turtle nesting potential for the entire Mediterranean. Other important nesting beaches for Mediterranean green turtles outside of Turkey include beaches in Latakia, Syria (Rees et al. 2010), and in North Karpaz and Alagadi in Cyprus (Casale & Margaritoulis 2010).

Türkozan & Kaska (2010) suggested that the exploration of two nesting sites at Sugözü and Alata Beaches may reveal significant nesting by green turtles, thus changing the current status of green turtles in the Mediterranean. Now we can add our new data from Davultepe, demonstrating the importance of this nesting beach for this species in the Mediterranean. Although sea turtle activity in Turkey has been studied for many years, there is still the potential to discover new significant nesting areas. Davultepe is an important example of this. The fact that Davultepe includes a 1.8-km section within Gümüşkum Natural Park offers a great opportunity for future protection and conservation of sea turtles.

Acknowledgements. We thank the Republic of Turkey Ministry of Forestry and Water Affairs, the 7^th Regional Directorate, Section of Mersin for the wire cages and warning plates.

AUREGGI, M., G. GEROSA, & S.V. YERLİ. 2000. Five years of research at Akyatan Beach (Turkey): one of the main nesting sites for the green turtle, Chelonia mydas, in the Mediterranean. Biogeographica 21: 555-560.

BARAN, İ. & M. KASPAREK. 1989. Marine turtles Turkey, status survey 1988 and recommendation for conservation and management: Prepared by WWF, Hedielberg. 123pp.

CANBOLAT, A.F. 2004. A review of sea turtle nesting activity along the Mediterranean coast of Turkey. Biological Conservation 116: 81-91.

CANBOLAT, A.F., K. ATATUNC, O. CANDAN & D. BARCAK. 2005. A new green turtle (Chelonia mydas) nesting site in the Mediterranean: Sugözü beaches, Adana (Turkey). In: Demetropoulos, A. & O. Turkozan (Eds.). Proceedings of the 2nd Mediterranean Conference on Sea Turtles. Barcelona Convention - Bern Convention - Bonn Convention. p. 65.

CASALE, P. & D. MARGARİTOULIS. 2010. Sea turtles in the Mediterranean: distribution threats and conservation priorities. Gland, Switzerland: IUCN. 294pp.

ERGENE, S. 2006. Opinion on the walking-track planned to be constructed along the coast of Davultepe (100. Yıl Beach), Report to Ministry of Environment and Forestry (in Turkish).

ERGENE, S., C. AYMAK, A.H. UÇAR, Y. KAÇAR & S.N. ŞENGEZER. 2010. A preliminary research on determining potential marine turtle nesting activity on Davultepe 100.Yıl Beach (Mersin). Ege Journal of Fisheries and Aquatic Sciences 27: 7-13.

ERGENE, S., A.H. UÇAR, C. AYMAK, S.N. ŞENGEZER, M. ERKEK, M. ERGENE, H. KORKMAZ & A. ELÇİ. 2012a. Research of marine turtles (Chelonia mydas and Caretta caretta) population between 2009 and 2012 nesting seasons in Davultepe 100. Yıl Beach in Mersin. Proceedings of the Fourth National Conference on Marine Turtles in Turkey. pp. 11-13.

ERGENE, S., Y. KAÇAR, A.H. UÇAR, C. AYMAK, S.N. ŞENGEZER, M. ERKEK & M. ERGENE. 2012b. Research, monitoring and conservation of marine turtles (Chelonia mydas and Caretta caretta) population nesting in the Gümüşkum Natural Park of Davultepe 100. Yıl Beach in Mersin between 2009 and 2012 nesting seasons. Final Report to Ministry of Forestry and Water Affairs. 35pp.

ERGENE, S., A.H. UÇAR & C. AYMAK. 2012c. Nesting sites of marine turtles in Mersin. Proceedings of Ministry of Forestry and Water Affairs Biodiversity Symposium, 22-23 May 2012. pp. 125-132.

ERGENE, S., Y. KAÇAR, A.H. UÇAR, C. AYMAK, M. ERKEK & M. ERGENE. 2013. Research, monitoring and conservation of marine turtles (Chelonia mydas & Caretta caretta) population in Kazanlı beach in Mersin. Final Report to Ministry of Forestry and Water Affairs. 147pp.

ERGENE, M. 2014. Sea turtles population [Chelonia mydas (Linnaeus, 1758) and Caretta caretta (Linnaeus, 1758)] which is nesting on Mersin Davultepe beach research of biological characteristic. M.Sc. thesis. Mersin University, Turkey. 107pp.

KASKA, Y., İ. BARAN, Y., Ç. ILGAZ, O. TÜRKOZAN, M. ÖZ & A. ERDOĞAN. 2005. An estimation of the total nesting activity of sea turtles in Turkey. In: Coyne, M.S. & R.D. Clark (Comps.) Proceedings of the 21st Annual Symposium on Sea Turtle Biology and Conservation, NOAA Tech Memo NMFS-SEFCS-528. pp. 204-205.

KASPAREK, M., B.J. GODLEY & A.C. BRODERICK. 2001. Nesting of the green turtle, Chelonia mydas, in the Mediterranean: A review of status and conservation needs. Zoology in the Middle East 24: 45-74.

MARGARITOULIS, D, R. ARGANO, İ. BARAN, F. BENTIVEGNA, M.N. BRADAI, J.A. CAMINAS, P. CASALE, G. DE METRIO, A. DEMETROPOULOS, G. GEROSA, B.J. GODLEY, D.A. HADDOUD, J. HOUGHTON, L. LAURENT & B. LAZAR. 2003. Loggerhead turtles in the Mediterranean Sea: Present knowledge and conservation perspectives. In: Bolten, A.B. & B.E. Witherington (Eds). Loggerhead Sea Turtles. Smithsonian Books. Washington D.C. USA. pp. 175-198.

REES, A.F., A. SAAD & M. JONY. 2010. Syria. In: Casale, P. & D. Margaritoulis (Eds.). Sea Turtles in the Mediterranean: Distribution, Threats and Conservation Priorities. IUCN/SSC Marine Turtle Specialist Group: Gland, Switzerland. pp. 233-243.

SÖNMEZ, B. 2013. Research and conservation of marine turtle (Chelonia mydas & Caretta caretta) population in Samandağ beach in Hatay (2013). Final Report. Samandağ; Turkey: Association of Environment Conservation and Tourism of Samandağ.

TÜRKOZAN, O. & Y. KASKA. 2010. Turkey. In: Casale, P. & D. Margaritoulis (Eds.). Sea Turtles in the Mediterranean: Distribution, Threats and Conservation Priorities. IUCN/SSC Marine Turtle Specialist Group: Gland, Switzerland. pp. 257-293.

YILMAZ, C., A. ORUÇ & O. TÜRKOZAN. 2015. Marine turtles (Chelonia mydas and Caretta caretta) nesting along the eastern Mediterranean coast of Turkey: Results from six years of surveying. Herpetological Journal 25: 197-204.