Mitochondrial DNA reveals regional and interregional importance of the central Mediterranean African shelf for loggerhead sea turtles (Caretta caretta)


  • Paolo Casale Department of Animal and Human Biology, University of Rome 1 ‘La Sapienza’
  • Daniela Freggi Sea Turtle Rescue Centre WWF Italy
  • Paolo Gratton Department of Biology, University of Rome 2 ‘Tor Vergata’
  • Roberto Argano Department of Animal and Human Biology, University of Rome 1 ‘La Sapienza’
  • Marco Oliverio Department of Animal and Human Biology, University of Rome 1 ‘La Sapienza’



Caretta caretta, mtDNA, Mixed Stock Analysis, conservation, Mediterranean


The wide north African continental shelf in the central Mediterranean is known to be one of the few important areas in the basin for loggerhead turtles in the neritic stage. In order to assess the origin of these turtles, sequences of the mtDNA control region were obtained from 70 turtles caught by bottom trawlers in the area, and compared with known sequences from turtles from Mediterranean and Atlantic nesting sites. Five haplotypes were identified (Haplotype diversity = 0.262; nucleotide diversity = 5.4×10-3). Specific haplotypes indicate contributions from distant rookeries such as Turkey and the Atlantic, which shows that Atlantic turtles entering the Mediterranean while in the oceanic phase use at least one Mediterranean continental shelf as a neritic foraging ground. A new haplotype and another one previously found only in foraging areas, highlight the genetic information gaps for nesting sites, which undermine powerful mixed stock analyses. Despite these limitations, the results reveal the regional importance of the study area as a neritic foraging ground for turtles that are probably from most of the Mediterranean nesting aggregates. Therefore, reducing turtle mortality resulting from the high fishing effort in the area should be regarded as key for Mediterranean turtle conservation and is also possibly important for Atlantic populations.


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Allendorf, F.W. and G. Luikart. – 2007. Conservation and the Genetics of Populations. Blackwell Publishing, Oxford, UK.

Bjorndal, K.A., A. Bolten and H.R. Martins. – 2000. Somatic growth model of juvenile loggerhead sea turtles Caretta caretta: duration of pelagic stage. Mar. Ecol. Prog. Ser., 202: 265-272. doi:10.3354/meps202265

Bolten, A.B. – 1999. Techniques for measuring sea turtles. In: K.L. Eckert, K.A. Bjorndal, F.A. Abreu-Grobois and M. Donnelly (eds.), Research and Management Techniques for the Conservation of Sea Turtles, pp. 110-114. IUCN/SSC Marine Turtle Specialist Group Publication No. 4.

Bolten, A.B. – 2003. Variation in sea turtle life history patterns: neritic vs. oceanic developmental stages. In: P.L. Lutz, J.A Musick and J. Wyneken (eds.), The Biology of Sea Turtles. Volume II, pp. 243-257. CRC Marine Biology Series, CRC Press, Inc.: Boca Raton, London, New York, Washington D.C.

Bowen, B.W., J.C. Avise, J.I. Richardson, A.B. Meylan, D. Margaritoulis, and S. Hopkins-Murphy. – 1993. Population structure of the loggerhead turtle Caretta caretta in the northwest Atlantic Ocean and Mediterranean Sea. Conserv. Biol., 37(4): 834-844. doi:10.1046/j.1523-1739.1993.740834.x

Bowen, B.W., A.L. Bass, S.M. Chow, M. Bostrom, K.A. Bjorndal, A.B. Bolten, T. Okuyama, B.M. Bolker, S. Epperly, E. Laca sella, D. Shaver, M. Dodd, S.R. Hopkins-Murphy, J.A. Musick, M. Swingle, K. Rankin-Baransky, W. Teas, W.N. Witzell and P.H. Dutton. – 2004. Natal homing in juvenile loggerhead turtles (Caretta caretta). Mol. Ecol., 13: 3797-3808. doi:10.1111/j.1365-294X.2004.02356.x PMid:15548292

Bowen, B.W., A.L. Bass, L. Soares and R.J. Toonen. – 2005. Conservation implications of complex population structure: lessons from the loggerhead turtle (Caretta caretta). Mol. Ecol., 14: 2389-2402. doi:10.1111/j.1365-294X.2005.02598.x PMid:15969722

Broderick, A.C., M.S. Coyne, W.J. Fuller, F. Glen and B.J. Godley. – 2007. Fidelity and over-wintering of sea turtles. Proc. R. Soc. B, 274: 1533-1538. doi:10.1098/rspb.2007.0211 PMCid:2176160

Carreras, C., S. Pont, F. Maffucci, M. Pascual, A. Barcelo, F. Bentivegna, L. Cardona, F. Alegre, M. SanFelix, G. Fernandez and A. Aguilar. – 2006. Genetic structuring of immature loggerhead sea turtles (Caretta caretta) in the Mediterranean Sea reflects water circulation patterns. Mar. Biol., 149: 1269-1279. doi:10.1007/s00227-006-0282-8

Carreras, C., M. Pascual, L. Cardona, A. Aguilar, D. Margaritoulis, A. Rees, O. Turkozan, Y. Levy, A. Gasith, M. Aureggi and M. Khalil. – 2007. The genetic structure of the loggerhead sea turtle (Caretta caretta) in the Mediterranean as revealed by nuclear and mitochondrial DNA and its conservation implications. Conserv. Genet., 8(4): 761-775. doi:10.1007/s10592-006-9224-8

Casale, P., D. Freggi, R. Basso and R. Argano. – 2005. Size at male puberty, sexing methods, and adult sex ratio in loggerhead turtles (Caretta caretta) from Italian waters investigated through tail measurements. Herp. J., 15: 145-148.

Casale, P., D. Freggi, R. Basso, C. Vallini and R. Argano. – 2007a. A model of area fidelity, nomadism, and distribution patterns of loggerhead sea turtles (Caretta caretta) in the Mediterranean Sea. Mar. Biol., 152: 1039-1049. doi:10.1007/s00227-007-0752-7

Casale, P., L. Cattarino, D. Freggi, M. Rocco and R. Argano. – 2007b. Incidental catch of marine turtles by Italian trawlers and longliners in the central Mediterranean. Aquatic Conserv.: Mar. Freshw. Ecosyst., 17: 686-701. doi:10.1002/aqc.841

Cross, H., C. Rizk, M. Khalil and L. Venizelos. – 2006. Population Status and Conservation Activities on Sea Turtle Nesting Beaches in South Lebanon, 2005. RAC/SPA (UNEP(MAP), Medasset, Ministry of Environment – Republic of Lebanon.

Dodd, C.K. Jr. – 1988. Synopsis of the biological data on the loggerhead sea turtle Caretta caretta (Linnaeus 1758). U.S. Fish Wildl. Serv., Biol. Rep., 88(14): 1-110.

Ehrhart, L.M., D.A.Bagley and W.E. Redfoot. – 2003. Loggerhead Turtles in the Atlantic Ocean: Geographic Distribution, Abundance, and Population Status. In: A.B. Bolten and B. Witherington (eds.), Loggerhead Sea Turtles, pp. 157-174, Smithsonian Institution Press, Washington, DC, USA.

Encalada, S.E., K.A. Bjorndal, A.B. Bolten, J.C. Zurita, B. Schroeder, E. Possardt, C.J. Sears and B.W. Bowen. – 1998. Population structure of loggerhead turtle (Caretta caretta) nesting colonies in the Atlantic and Mediterranean as inferred from mitochondrial DNA control region sequences. Mar. Biol., 130: 567-575. doi:10.1007/s002270050278

Groombridge, B. – 1990. Marine turtles in the Mediterranean: distribution, population status, conservation. Report to the Council of Europe, Environment Conservation and Management Division, Nature and Environment Series No. 48. Strasbourg.

Heppell, S.S. – 1998. Application of life-history theory and population model analysis to turtle conservation. Copeia, 1998(2): 367-375. doi:10.2307/1447430

Hillis, D.M., A. Larson, S.K. Davis and E.A. Zimmer. – 1990. Nucleic Acids II: Sequencing. In: D.M. Hillis and C. Mortiz (eds.), Molecular Systematics, pp. 318-370. Sinauer Associates, Sunderland, Massachusetts, USA.

Jribi, I., M.N. Bradai and A. Bouain. – 2007. Impact of trawl fishery on marine turtles in the Gulf of Gabès, Tunisia. Herp. J., 17: 110-114.

Kaska, Y. – 2000 Genetic structure of Mediterranean sea turtle populations. Turk. J. Zool., 24(2): 191-197.

Laurent, L., P. Casale, M.N. Bradai, B.J. Godley, G. Gerosa, A.C. Broderick, W. Schroth, B. Schierwater, A.M. Levy, D. Freggi, E.M. Abd El-Mawla, D.A. Hadoud, H.E. Gomati, M. Domingo, M. Hadjichristophorou, L. Kornaraky, F. Demirayak and Ch. Gautier. – 1998. Molecular resolution of marine turtle stock composition in fishery bycatch: a case study in the Mediterranean. Mol. Ecol., 7: 1529-1542. doi:10.1046/j.1365-294x.1998.00471.x PMid:9819906

Laurent, L., M.N. Bradai, D.A. Hadoud, H.M. El Gomati and A. Hamza. – 1999. Marine turtle nesting activity assessment on Libyan coasts. Phase 3: Survey of the coast to the west of Misratah. Marine Biology Research Centre (Tajura, Libya), MEDASET, RAC/SPA (MAP-UNEP), TCEP (Tripoli), WWF International Mediterranean Programme (Rome).

Limpus, C.J. – 1994. The loggerhead turtle, Caretta caretta, in Queensland: feeding ground selection following her first nesting season. In: K.A. Bjorndal, A.B. Bolten, D.A. Johnson and P.J. Eliazar (Compilers), Proc. 14th Ann. Symp. Sea Turtle Biol. and Conserv., pp. 78-81. NOA Technical Memorandum NMFS-SEFSC-351.

Limpus, C.J. and D.J. Limpus. – 2001 The loggerhead turtle, Caretta caretta, in Queensland: breeding migrations and fidelity to a warm temperate feeding area. Chel. Conserv. Biol., 4(1): 142-153.

Maffucci, F., W.H.C.F. Kooistra and F. Bentivegna. – 2006. Natal origin of loggerhead turtles, Caretta caretta, in the neritic habitat off the Italian coasts, Central Mediterranean. Biol. Conserv., 127: 183-189. doi:10.1016/j.biocon.2005.08.009

Margaritoulis, D., R. Argano, I. Baran, F. Bentivegna, M.N. Bradai, J.A. Caminas, P. Casale, G. De Metrio, A. Demetropoulos, G. Gerosa, B. Godley, J. Houghton, L. Laurent and B. Lazar. – 2003. Loggerhead turtles in the Mediterranean Sea: present knowledge and conservation perspectives. In: A.B. Bolten and B. Witherington (eds.), Loggerhead Sea Turtles, pp. 175‑198, Smithsonian Institution Press, Washington, DC, USA.

Marquez, M. R. – 1990. Sea turtles of the world. FAO Fish. Synopsis No. 125, Vol. 11. Rome.

Mingozzi, T., G. Masciari, G. Paolillo, B. Pisani, M. Russo and A. Massolo. – 2007. Discovery of a regular nesting area of loggerhead turtle Caretta caretta in southern Italy: a new perspective for national conservation. Biodiversity Conserv., 16: 3519-3541. doi:10.1007/s10531-006-9098-6

Oliverio, M. and P. Mariottini. – 2001. Contrasting morphological and molecular variation in Coralliophila meyendorffii (Muricidae, Coralliophilinae). J. Molluscan Stud., 67: 243-246. doi:10.1093/mollus/67.2.243

Pella, J. and M. Masuda. – 2001. Bayesian methods for analysis of stock mixtures from genetic characters. Fish. Bull., 99: 151–167.

Rozas, J., J. C Sánchez-Delbarrio, X. Messeguer and R. Rozas. – 2003. DnaSP, DNA polymorphism analyses by the coalescent and other methods. Bioinformatics, 19: 2496–2497. doi:10.1093/bioinformatics/btg359 PMid:14668244

Revelles M., C. Carreras, L. Cardona, A. Marco, F. Bentivegna, J.J. Castillo, G. de Martino, J.L. Mons, M.B. Smith, C. Rico, M. Pascual and A. Aguilar. – 2007. Evidence for an asymmetrical size exchange of loggerhead sea turtles between the Mediterranean and the Atlantic through the Straits of Gibraltar. J. Exp. Mar. Biol. Ecol., 349: 261–271. doi:10.1016/j.jembe.2007.05.018

Sambrook, J. and D.W. Russell. – 2000. Molecular Cloning. Cold Spring Harbor Laboratory Press, Cold Spring Harbor, NY. Schroth, W., B. Streit and B. Schierwater. – 1996. Evolutionary handicap for turtles. Nature, 384: 521-522.

Staden, R., K.F. Beal and J.K. Bonfield. – 1998. The Staden Package. In: S. Misener and S.A. Krawetz (eds.), Methods in Molecular Biology. Bioinformatics Methods and Protocols, pp. 115-130. The Humana Press Inc., Totowa, NJ.

Staden, R., D.P. Judge and J.K. Bonfield. – 2005. Sequence assembly and finishing methods. In: A.D. Baxevanis and B.F. Francis Ouellette (eds.), Bioinformatics: A Practical Guide to the Analysis of Genes and Proteins. Second Edition. John Wiley and Sons, New York, NY, USA.

Thompson, J.D., T.J. Gibson, F. Plewniak, F. Jeanmougin and D.G. Higgins. – 1997. The ClustalX Windows interface: flexible strategies for multiple sequences alignment aided by quality analysis tools. Nucleic Acids Res., 25: 4876-4882. doi:10.1093/nar/25.24.4876 PMid:9396791    PMCid:147148

Zaykin, D.V., A.I. Pudovkin – 1993. Two programs to estimate significance of X2 values using pseudo-probability tests. J. Heredity, 84: 152.




How to Cite

Casale P, Freggi D, Gratton P, Argano R, Oliverio M. Mitochondrial DNA reveals regional and interregional importance of the central Mediterranean African shelf for loggerhead sea turtles (Caretta caretta). scimar [Internet]. 2008Sep.30 [cited 2022Dec.8];72(3):541-8. Available from:




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