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Marine Turtle Newsletter 111:, ©

Marine Turtle Newsletter-Online

Charybdis hellerii, a Non-indigenous Portunid Crab from the Gastrointestinal Contents of a Kemp’s Ridley Sea Turtle (Lepidochelys kempi) in Georgia, USA

Michael G. Frick & Kristina L. Williams
Caretta Research Project, P.O. Box 9841, Savannah, Georgia, USA (E-mail: caretta05@aol.com)

The portunid crab Charybdis hellerii originates from the Indo-Pacific region (Japan, Philippines, New Caledonia, Australia and Hawaii) and the Indian Ocean (including the Red Sea). This species was introduced into the eastern Mediterranean (Israel and Egypt) via the Suez Canal and ship traffic from this region is likely responsible for introducing C. hellerii to Colombia, Venezuela and Cuba. Recently, C. hellerii has expanded its range in the western North Atlantic, presumably through larval dispersal, to the Indian River lagoon system in Fort Pierce, Florida, USA, Brazil and French Guiana (Dineen et al. 2001). Here we report the occurrence of C. hellerii from the stomach contents of an immature Kemp’s ridley sea turtle (Lepidochelys kempi) from Georgia, USA – the first record of C. hellerii as a prey item of sea turtles and a range extension for this non-indigenous decapod.

An immature L. kempi was found dead on the beach at Wassaw Island, Georgia, USA (31°53’N, 80°50’W) at 0600 hours on 11 June 2003. The turtle measured 43.1 cm (straight carapace length) and 45.4 cm wide and bore no external signs of injury or decomposition. Internal analyses of the turtle suggested that the animal was healthy prior to death as all viscera were intact and appeared normal, the animal was not emaciated and the gastrointestinal (GI) tract was full of prey items.

The GI tract of the turtle consisted primarily of adult-sized crabs: Libinia dubia, Libinia emarginata, Hepatus epheliticus, Persephona mediterranea, Panopeus herbstii and Porcellana sayana (in descending order of the amount of each prey item observed). Approximately 1/3 of the turtle’s GI tract contained tubicolous polychaete worms, Diopatra cuprea. Moon snails, Polinices duplicatus, were the least common prey item observed from the turtle. Amongst the aforementioned prey items encountered were the remains of an unidentified portunid crab. The specimen was in two large pieces consisting primarily of the walking legs and chelipeds – obviously crushed in half when consumed by the turtle.

Further analyses of the portunid revealed it to be C. hellerii. Despite the condition of the crab’s carapace, six anterolateral marginal teeth and a single spine on the postero-marginal border of the carpus of each fifth walking leg aided in the identification of the specimen (Lemaitre 1995). Because the carapace was damaged, we estimated the size of the C. hellerii using data presented by Mantelatto and Garcia (2001), where the authors demonstrated the relative growth of carapace width in relation to the length and height of the propodus of the major chelae. These data are also presented with respect to gender and life stage of C. hellerii. The morphometrics of the C. hellerii major chelae propodus was 21.1 mm high and 63.2 mm long, placing the specimen somewhere between 60 and 70 mm carapace width, and likely an adult male (see data presented by Mantelatto and Garcia 2001).

In Florida, Charybdis hellerii occurs in high densities in estuarine habitats consisting of both muddy and sandy sediments (Dineen et al. 2001). Specimens are found amongst and under rocks, oysters, dense algal growth, mangrove roots and coralline ledges - habitats similar to those of foraging turtles. A congener of C. hellerii, C. natator, occupies similar habitats to C. hellerii and has been documented from the diets of loggerhead turtles (Caretta caretta) in Australia (Limpus et al. 2001). It is possible that C. hellerii is or may become an important prey item for western Atlantic turtles. In areas like the Indian River Lagoon in Florida, where L. kempi often forage and where C. hellerii is firmly established, it would be interesting to note the presence or absence of C. hellerii in local turtles and, if the crab does occur from turtles, what percent of the diet consists of C. hellerii.

Acknowledgements: We thank the U.S. Fish and Wildlife Service, the Georgia Department of Natural Resources, the Wassaw Island L.L.C. and the PADI Foundation for supporting our epibiont research. We also than J. Dineen and R. Lemaitre for providing us with reprints of their work cited herein. Two anonymous reviewers greatly improved an earlier draft of this manuscript.

DINEEN, J.F., P.F. CLARK, A.H. HINES, S.A. REED & H.P. WALTON. 2001. Life history, larval description, and natural history of Charybdis hellerii (Decapoda, Brachyura, Portunidae), an invasive crab in the western Atlantic. Journal of Crustacean Biology 21: 774-805.

LEMAITRE, R. 1995. Charybdis hellerii (Milne Edwards, 1867), a nonindigenous portunid crab (Crustacea: Decapoda: Brachyura) discovered in the Indian River lagoon system of Florida. Proceedings of the Biological Society of Washington 108: 643-648.

LIMPUS, C.J., D.L. DE VILLIERS, M.A. DE VILLIERS, D.J. LIMPUS & M. READ. 2001. The loggerhead turtle, Caretta caretta in Queensland: feeding ecology in warm temperate waters. Memoirs of the Queensland Museum 46: 631-645.

MANTELLATO, F.L.M. & R.B. GARCIA. 2001. Biological aspects of the nonindigenous portunid crab Charybdis hellerii in the western tropical South Atlantic. Bulletin of Marine Science 68: 469-477.