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RESEARCH NOTES 474 /. Moll Stud. (1997), 63,474-476 © The Malacological Society of London 1997 MolJuscan and crustacean hems in the diet of the loggerhead turtle, Caretta caretta (Linnaeus, 1758) [Testudines: Chelonidae] in the eastern Mediterranean BJ. Godley1*2, S.M. Smith3, P.F. Clark* and J.D. Taylor4 'Institute of Biomedical and Life Sciences, Graham Ken Building, University of Glasgow, Glasgow G12 8QQ, U.K. (e-mail [email protected]) 2 Department of Veterinary Anatomy, University of Glasgow Veterinary School, Glasgow G611QH, U.K. 3 Woodleigh, Townhead, Hayton, Carlisle CA4 9JH, U.K. 4 Natural History Museum, Cromwell Road, London, SW7 5BD, U.K. The loggerhead turtle (Caretta caretta) has a circumglobal distribution in temperate and subtropical areas including the whole of the Mediterranean.1 However, little dietary information is available for those individuals foraging in this region. After hatching on the natal beach, marine turtles undergo a poorly understood pelagic life history phase, where they are thought to feed upon planktonic items for a number of years.13 Following this, turtles migrate into a juvenile developmental habitat, usually demersal and neritic. It is thought that they remain in these areas until they reach adulthood, at which time they begin migrations to seasonal breeding grounds, which they may undertake every few years.3 For both post-pelagic juveniles and adults of this species, study of prey items in other regions of the world have found the diet to be dominated by benthic molluscs, crustaceans and coelenterates.1 Loggerhead turtles off Australia have recently been observed 'mining' such prey items in soft sediments.4 Individuals sold in markets in Sfax, Tunisia in 1989, were observed to have previously ingested benthic molluscs and Crustacea.5 Identification of gut contents from 31 individuals of varying sizes, caught by trawlers in Tunisian waters, showed the diet to consist largely of these two groups, but also of echinoderms and other items in relatively small proportions.6 These data suggest that certainly in this region, the loggerhead is a fairly non-selective predator upon sessile and slow moving prey. Necropsy examinations of two loggerhead turtles were undertaken as part of an ongoing study of mortality patterns in Mediterranean marine turtles (B.G.). Lesions present strongly suggested that both individuals had been killed as the result of interactions with local artisanal fisheries in Famagusta Bay, off the coast of northern Cyprus. Both individuals showed signs of cranial trauma, were recently dead, in good general body condition and had digestive tracts relatively full of prey items when they were washed ashore. The first turtle, a subadult female (individual A), with a standard curved carapace length of 49 cm, was discovered on 6th September, 1994. This individual was likely to have been resident in the region. An adult male (individual B), with a standard curved carapace length of 76 cm, was discovered on the 7th June, 1995. The breeding season, in this region, is known to occur at the same time of year as the dis- covery of this individual.7 Although this male may have been locally resident, it might also have been a breeding migrant from a distant feeding ground. Guts were incised and all dietary items expected to be identifiable were collected and fbted for later taxonomic identification. Mollusc shell fragments were identified according to an established guide8 (S.S.) and opercula were identified by comparison with specimens in the Mollusca collections of the Natural History Museum, London (J.T.). Crustacea were identified according to existing publications for [Anomura: Paguridae] and [Brachyura: Majidae]9"13 and then compared with material in the reference collection of the Natural History Museum (P.C.). The dietary items identified, substrate and depth where the species are normally found, and minimum numbers of each prey species recorded for each individual are shown in Table 1. Five of these genera (Cerithium, Hexaplex, Fasciolaria, Pagurus and Pagunstes) have been previously recorded as prey items in this turtle species in the Mediterranean.6 Outside this region, at least six of these genera (Astraea, Cerithium, Conus, Strombus, Pagurus, Paguristes) have previously been recorded as prey items for the loggerhead turtle.1 The occurrence of Strombus decorus raybaudi (identified from opercula) in the diet is noteworthy since this species has diversified morphologically since invading the eastern Mediterranean via the Suez canal from the Indian Ocean-Red Sea.14 It is difficult to generalise from such a limited sample size, however there was considerable overlap in prey items between both individuals. From general inspection of fragments, several other facts could be ascertained. Both individuals crushed, even the most robust, prey items before swallowing and there was no apparent difference in size of prey selected by different individuals, in that most mollusc fragments originated from shells of range 10-30 mm. Distribution data pertaining to the prey species suggest that loggerhead turtles in the eastern Mediterranean do indeed feed upon benthic molluscs and Crustacea, at shallow to moderate depths, from both rocky and sedimentary habitats. It is strongly recommended that similar studies are carried out upon incidentally caught or stranded turtles within this region, to allow greater understanding of the synecology of this endangered population. rock sand & mud rock rock rock Buccinulum corneum (Linnaeus, 1758) Fusinus syracusanus (Linnaeus, 1758) Fasciolaria lignaria (Linnaeus, 1758) Conus ventricosus (Gmelin, 1791) Anomiidae spp. rock sand sandy-mud rock sand & seagrass Hexaplex trunculus (Linnaeus, 1758) Superclass: Crustacea Class: Malacostraca Infradorder: Anomura Pagurus anachoretus (Risso, 1827) Family: Paguridae Pagurus cuanensis (Bell, 1845) Paguristes eremita (Linnaeus, 1767) Infraorder: Brachyura Maja goltziana (d'Oliviera, 1888) Family: Majidae Class: Bivalva sand Phalium undulatum (Gmelin, 1791) 6-10 m occ. 100 m 15-91 m 10-80 m 15-200 m 0-20 m 0-20 m 0-20 m 1-50 m intertidal-27 m 1-100 m 8-80 m >25m sand & mud Naticarius stercusmuscarum (Gmelin, 1791) intertidal-20 m 0-20 m sand & mud Cerithium vulgatum (Bruguiere, 1792) 8-59 m Depth Strombus decorus raybaudi (Nikolay & Manoja, 1983) sand sand rock Astraea rugosa (Linnaeus, 1767) Class: Gastropoda Substrate Species Phylum: Mollusca (SH. &O.) - (SH. &O.) 4 1 1 2 1 (SH.) 1 - _ (SH.) 1 (SH.) (SH.) 20 1 (SH.) (SH.) 8 (SH.) 20 6 4 (O.) 5 (SH.) 30 39 (SH.) _ (O.) 100 — Individual B 40 (SH.) 1 _ (SH.) 6 (SH.) 6 Individual A Table 1. Classification of prey items found, substrate and depths where they are normally found. Minimum numbers in both turtle individuals A and B are given. (Key: SH.= Identified by shell fragments, O. = Identified by opercula) a In z o o /0 S 3 tn rn RESEARCH NOTES 476 We would like to acknowledge the help of Glasgow University Turtle Conservation Expedition members, A.C. Broderick, K. Dodd Jr., E.G. Hancock, L. Laurent, M. Reilly and F. Woodward. B.G. is funded by a post-graduate scholarship from the University of Glasgow and would like to acknowledge further supervision and material support from Dr. R.W. Furness and Prof. S.E. Solomon, both of University of Glasgow. REFERENCES 1. DODD, JR., C.K. 1988. BioL Rep., 88 (14) F.A.O. Synopsis NMFS-149. 2. PLOTKIN, P.T. 1996. Chelon, Cons. BioL, 2:78-80. 3. MUSICK, J.A. & LIMPUS, CJ. 1997. In: The Biol- 6. LAURENT, L. & LESCURE, J. 1994. Rev. EcoL (Terre Vie), 49:63-86. 7. BRODERICK, A.C. & GODLEY, BJ. 1996. ZooL Middle East, 13:27^46. 8. POPPE, G.T. & GOTO, Y. 1991. European Sea Shells, Volume 1. Verlag Christa Hemmen, Weisbaden. 9. CAPART, A. 1951. Resultats Scientifiques, 3: 11205. 10. INGLE, R.W. 1993. Hermit crabs of the North-eastern Atlantic Ocean and the Mediterranean Sea: An illustrated key. Natural History Museum Publications & Chapman & Hall: London. 11. LEWINSOHN, C.H. & HOLTHUIS, L.B. 1980. ZooL Verharu, 230:1-64. 12. MANNING, R.B. & FROGUA, C. 1982. Quaderni del Laboratorio di Tecnologia della Pesca., 3 (25): 319-334. ogy of Sea Turtles (P.L. Lutz & J.A. Musick, eds): 184-254. CRC Press, Boca Raton. 4. PREEN, A.R. 19%.7. Herpetol.,30:94-6. 13. ZARIQUIEY ALVAREZ, R. 1968. Investigacion 5. LAURENT, L. & LESCURE, J. 1992. Proc Sixth 14. NICOLAY, K. Ord. Gen. Meet S.E.H., Budapest, 1991: 293-295. Pesquera (Barcelona), 32:9. & MANOJA, E.R. 1983. La Conchiglia, IS (176-7): 17-18. © The Malacological Society of London 1997 J. MolL Stud, (1997), 63,476-478 First report of shell boring predation by a member of the Nassariidae (Gastropoda) Brian Morton and K. Chan The Swire Institute of Marine Science, The University of Hong Kong, Cape d'Aguilar, Shek O, Hong Kong Shell boring predation occurs in a range of animal groups1, but is most well-studied in the prosobranch gastropods, notably representatives of the Naticidae and Muricidae2. In both families, a wide range of species engage in such predation activities and characteristic boreholes in their even more diverse prey are evidence of this and provide further evidence in the fossil record for the origins of such activities2. Muricid boreholes are generally straight-sided and such borers are characterized by the presence of an accessory boring organ in the foot3. The naticid borehole is countersunk, or bevelled, at the edges and there is also an accessory boring organ, but this time on the ventral surface of the proboscis.4 In representatives of both families, therefore, boring is by chemical dissolution using secretions from an accessory boring organ. The boring organs, independently evolved in both groups, are assisted by mechanical abrasion using the radula. There is also a suggestion that species of Cominella (Buccinidae) from Western Australia bore their bivalve prey5. A fourth, less wellstudied, family, some of which, e.g., Austroginella sp., are shell borers, is the Marginellidae6. The Cassidae (Neotaenioglossa) are specialist, hole-making (but not boring), echinoderm predators7. Representatives of the Nassariidae are herbiv- orous, carnivorous or scavenging members of the Neogastropoda. There is an extensive literature on scavenging in the numerous species of the Nassariidae much of which has been reviewed and they are considered to be 'the closest attempt of an obligate scavenging life style'8, along with the amphipod Lysianassidae. The spatial and temporal ephemerality of carrion in the sea, however, it is argued8, can only sustain facultative scavengers. Yet, in the Nassariidae, only Bullia digitalis9 and Ilyanassa obsoleta10 are known to eat live prey, but not by boring. B. digitalis is also known to consume algae". Three reports mention12"14, in passing, that nassariids are shell borers, but there is no confirmatory evidence of this and, hitherto, to the contrary, it has been generally assumed that species of this family are incapable of such activity. This study provides the first evidence of shell boring in a member of the Nassariidae and was obtained in a wholly accidental manner. Nassarius festivus (Powys, 1835) is the most common and widely distributed nassariid on Hong Kong's soft shores and is, undoubtedly, a scavenger13. Where in Hong Kong, for example, either pollution creates a stressed biota on beaches or where trash fish discarded by fishermen float ashore, numbers of N. festivus are elevated enormously and they readily and