Sea turtle diving and foraging behaviour around the Greek Island of Kefalonia

Houghton, Jonathan D. R.; Woolmer, Andrew; Hays, Graeme C.

doi:10.1017/s002531540000271x

Cited by 36 publications

(39 citation statements)

References 4 publications

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“…Certainly some loggerhead turtles do feed at Cyprus, as evidenced by gut content analysis (unpubl.). Furthermore we have recently shown, by direct observation, that adult loggerhead turtles feed close to nesting beaches in Greece (Houghton et al 2000), suggesting that foraging during the nesting season may be widespread in this species in the Mediterranean. We might tentatively speculate that Turtle 1 (longer dives) spent more time resting on the seabed while Turtle 2 (shorter dives) spent more time foraging.…”

Section: Discussionmentioning

confidence: 84%

“…For example, in addition to the increased benthic for- aging opportunities for thecate species, turtles may be able to conserve valuable resources through resting. By adjusting the amount of inspired air to a depth where it intends to dive, a turtle may be able to remain neutrally buoyant for much of a dive (Houghton et al 2000). As such, given that air becomes compressed with depth in line with Boyle's law, a turtle is able to dive with a larger lung volume when diving deeper and still attain neutral buoyancy.…”

Section: Discussionmentioning

confidence: 99%

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Diving behaviour during the internesting interval for loggerhead turtles Caretta caretta nesting in Cyprus

Houghton¹,

Broderick²,

Godley³

et al. 2002

Mar. Ecol. Prog. Ser.

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Time depth recorders were used to assess the patterns of depth utilisation by 2 loggerhead turtles Caretta caretta in Cyprus, eastern Mediterranean. Dives to the seabed accounted for 59% (171 h) and 75% (215 h) of the internesting interval, respectively, with most dives being shallow (< 20 m), suggesting the turtles remained close to the shore. These benthic dives decreased markedly in the days following or prior to a nesting event, suggesting that the behaviours associated with nesting may be protracted. This importance of the seabed for loggerhead turtles in Cyprus contrasts with the far more extensive use of mid-water resting dives recently reported for this species in Japan. Our evidence suggests that this dichotomy may reflect differences in the amount of time spent travelling, with mid-water resting occurring when turtles are travelling and, conversely, when little time is spent travelling turtles opt to remain predominantly on the seabed.

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Section: Discussionmentioning

confidence: 84%

Section: Discussionmentioning

confidence: 99%

Diving behaviour during the internesting interval for loggerhead turtles Caretta caretta nesting in Cyprus

Houghton¹,

Broderick²,

Godley³

et al. 2002

Mar. Ecol. Prog. Ser.

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“…Turtle behaviour derived from depth-sensing tags suggested they were benthic divers. Dive characteristics for most hard-shelled sea turtles are related to aerobic limits, showing longer-duration dives possible in colder water (Southwood et al 2003, Broderick et al 2007, Hochscheid et al 2007), due to thermal dependence of metabolism, and a positive relationship between dive depth and maximum dive duration , Houghton et al 2000. However, olive ridley turtles from Australia have been shown to have unusual dive characteristics, capable of dives in excess of 3 h in warm seas (McMahon et al 2007).…”

Section: Discussionmentioning

confidence: 99%

Conservation related insights into the behaviour of the olive ridley sea turtle Lepidochelys olivacea nesting in Oman

Rees¹,

Al-Kiyumi²,

Broderick³

et al. 2012

Mar. Ecol. Prog. Ser.

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“…Loggerhead sea turtles consume a wide array of prey, including jellyfish, cephalopods and fish (Bjorndal, 1997;Houghton et al, 2000;Tomás et al, 2001;Bentivegna et al, 2003). Fish have been suggested to be a relevant component of the species' diet in the western Mediterranean (Tomás et al, 2001), but the trophic level of the loggerhead sea turtles found off the Balearic Archipelago, as revealed by the δ 15 N (Peterson and Fry, 1987), is much lower than that of typical ichthyophagous species from the same area Jennings et al, 1997;Pinnegar and Polunin, 2000;Polunin, 2001).…”

mentioning

confidence: 99%

Stable C and N isotope concentration in several tissues of the loggerhead sea turtle <i>Caretta caretta</i> from the western Mediterranean and dietary implications

et al. 2007

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SUMMARY:The isotopic concentrations of carapace scutes, skin, muscle and blood of loggerhead sea turtles (Caretta caretta) from the Balearic Archipelago were analysed to investigate the pattern of variation between tissues and to assess the position of this species in the trophic webs of the Algerian Basin. Skin showed higher δ 13 C values than muscle or carapace scutes and these showed higher values than blood. Conversely, muscle showed higher δ 15 N values than skin, skin showed higher values than blood and blood showed higher values than carapace scutes. Dead and live sea turtles from the same habitat did not differ in the concentration of stable isotopes. However, some of the tissues of the turtles caught in drifting longlines in the oceanic realm showed higher δ 13 C values than those from the turtles caught by hand or in trammel nets over the continental shelf, although they did not differ in the δ 15 N. Comparison of the concentration of stable isotopes in the turtles with that of other species from several areas of the Algerian Basin revealed that they consumed planktonic prey and that the trophic level of the sea turtles was higher than that of carnivorous cnidarians but lower than that of zooplanktophagous fish and crustaceans.Keywords: tissues, stable isotopes, sea turtle, trophic level, feeding ecology, carbon, nitrogen. RESUMEN: CONCENTRACIÓN DE ISÓTOPOS ESTABLES DE C Y N EN VARIOS TEJIDOS DELA TORTUGA BOBA CARETTA CARETTA DEL MEDITERRÁNEO OCCIDENTAL E IMPLICACIONES SOBRE LA DIETA. -La concentración isotópica de escudos del caparazón, piel, músculo y sangre de tortuga boba (Caretta caretta) fueron analizados para investigar el patrón de variación entre tejidos y para evaluar la posición de esta especie en las redes tróficas de la cuenca Argelina. La piel presentaba valores más altos de δ 13 C que el músculo o los escudos del caparazón y éstos presentaban valores más altos que la sangre. En cambio, el múscu-lo presentaba valores más altos de δ 15 N que la piel, ésta valores más altos que la sangre y ésta valores más altos que los escudos del caparazón. Las tortugas muertas y las vivas del mismo hábitat no diferían en la concentración de isótopos estables. Sin embargo, alguno de los tejidos de las tortugas capturadas mediante palangre de superficie en el medio oceánico presentaban valores más altos de δ 13 C que los de las tortugas capturadas a mano o mediante trasmallo en la plataforma continental, aunque no diferían en el δ 15 N. La comparación de la concentración de isótopos estables de tortuga con la de otras especies de varias áreas de la cuenca Argelina reveló que consumían presas planctónicas y que el nivel trófico de las tortugas era superior que el de los cnidarios carnívoros pero inferior que el de peces y crustáceos zooplanctófagos.

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Sea turtle diving and foraging behaviour around the Greek Island of Kefalonia

Cited by 36 publications

References 4 publications

Diving behaviour during the internesting interval for loggerhead turtles Caretta caretta nesting in Cyprus

Diving behaviour during the internesting interval for loggerhead turtles Caretta caretta nesting in Cyprus

Conservation related insights into the behaviour of the olive ridley sea turtle Lepidochelys olivacea nesting in Oman

Stable C and N isotope concentration in several tissues of the loggerhead sea turtle <i>Caretta caretta</i> from the western Mediterranean and dietary implications

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