FRINK Linked Data Fragments server

Matches in SemOpenAlex for { <https://semopenalex.org/work/W2150126293> ?p ?o ?g. }

• W2150126293 endingPage "133" @default.
• W2150126293 startingPage "126" @default.
• W2150126293 abstract "Marine turtles are renowned long-distance navigators, able to reach remote targets in the oceanic environment; yet the sensory cues and navigational mechanisms they employ remain unclear [1Alerstam T. Conflicting evidence about long-distance animal navigation.Science. 2006; 313: 791-794Crossref PubMed Scopus (122) Google Scholar, 2Bingman V.P. Cheng K. Mechanisms of animal global navigation: Comparative perspectives and enduring challenges.Ethology, Ecology, and Evolution. 2006; 17: 295-318Crossref Scopus (99) Google Scholar, 3Lohmann K.J. Lohmann C.M.F. Sea turtles, lobsters, and oceanic magnetic maps.Marine and Freshwater Behavior and Physiology. 2006; 39: 49-64Crossref Scopus (40) Google Scholar]. Recent arena experiments indicated an involvement of magnetic cues in juvenile turtles' homing ability after simulated displacements [4Lohmann K.J. Lohmann C.M.F. Ehrhart L.M. Bagley D.A. Swing T. Geomagnetic map used in sea-turtle navigation.Nature. 2004; 428: 909-910Crossref PubMed Scopus (207) Google Scholar, 5Avens L. Lohmann K.J. Navigation and seasonal migratory orientation in juvenile sea turtles.J. Exp. Biol. 2004; 207: 1771-1778Crossref PubMed Scopus (44) Google Scholar], but the actual role of geomagnetic information in guiding turtles navigating in their natural environment has remained beyond the reach of experimental investigations. In the present experiment, twenty satellite-tracked green turtles (Chelonia mydas) were transported to four open-sea release sites 100-120 km from their nesting beach on Mayotte island in the Mozambique Channel; 13 of them had magnets attached to their head [6Papi F. Luschi P. Åkesson S. Capogrossi S. Hays G.C. Open-sea migration of magnetically disturbed sea turtles.J. Exp. Biol. 2000; 203: 3435-3443PubMed Google Scholar] either during the outward journey or during the homing trip. All but one turtle safely returned to Mayotte to complete their egg-laying cycle, albeit with indirect routes, and showed a general inability to take into account the deflecting action of ocean currents as estimated through remote-sensing oceanographic measurements [7Girard C. Sudre J. Benhamou S. Roos D. Luschi P. Homing in green turtles Chelonia mydas: Oceanic currents act as a constraint rather than as an information source.Mar. Ecol. Prog. Ser. 2006; 322: 281-289Crossref Scopus (50) Google Scholar]. Magnetically treated turtles displayed a significant lengthening of their homing paths with respect to controls, either when treated during transportation or when treated during homing. These findings represent the first field evidence for the involvement of geomagnetic cues in sea-turtle navigation. Marine turtles are renowned long-distance navigators, able to reach remote targets in the oceanic environment; yet the sensory cues and navigational mechanisms they employ remain unclear [1Alerstam T. Conflicting evidence about long-distance animal navigation.Science. 2006; 313: 791-794Crossref PubMed Scopus (122) Google Scholar, 2Bingman V.P. Cheng K. Mechanisms of animal global navigation: Comparative perspectives and enduring challenges.Ethology, Ecology, and Evolution. 2006; 17: 295-318Crossref Scopus (99) Google Scholar, 3Lohmann K.J. Lohmann C.M.F. Sea turtles, lobsters, and oceanic magnetic maps.Marine and Freshwater Behavior and Physiology. 2006; 39: 49-64Crossref Scopus (40) Google Scholar]. Recent arena experiments indicated an involvement of magnetic cues in juvenile turtles' homing ability after simulated displacements [4Lohmann K.J. Lohmann C.M.F. Ehrhart L.M. Bagley D.A. Swing T. Geomagnetic map used in sea-turtle navigation.Nature. 2004; 428: 909-910Crossref PubMed Scopus (207) Google Scholar, 5Avens L. Lohmann K.J. Navigation and seasonal migratory orientation in juvenile sea turtles.J. Exp. Biol. 2004; 207: 1771-1778Crossref PubMed Scopus (44) Google Scholar], but the actual role of geomagnetic information in guiding turtles navigating in their natural environment has remained beyond the reach of experimental investigations. In the present experiment, twenty satellite-tracked green turtles (Chelonia mydas) were transported to four open-sea release sites 100-120 km from their nesting beach on Mayotte island in the Mozambique Channel; 13 of them had magnets attached to their head [6Papi F. Luschi P. Åkesson S. Capogrossi S. Hays G.C. Open-sea migration of magnetically disturbed sea turtles.J. Exp. Biol. 2000; 203: 3435-3443PubMed Google Scholar] either during the outward journey or during the homing trip. All but one turtle safely returned to Mayotte to complete their egg-laying cycle, albeit with indirect routes, and showed a general inability to take into account the deflecting action of ocean currents as estimated through remote-sensing oceanographic measurements [7Girard C. Sudre J. Benhamou S. Roos D. Luschi P. Homing in green turtles Chelonia mydas: Oceanic currents act as a constraint rather than as an information source.Mar. Ecol. Prog. Ser. 2006; 322: 281-289Crossref Scopus (50) Google Scholar]. Magnetically treated turtles displayed a significant lengthening of their homing paths with respect to controls, either when treated during transportation or when treated during homing. These findings represent the first field evidence for the involvement of geomagnetic cues in sea-turtle navigation. Experimental displacements constitute one useful approach to investigating animal navigation systems [2Bingman V.P. Cheng K. Mechanisms of animal global navigation: Comparative perspectives and enduring challenges.Ethology, Ecology, and Evolution. 2006; 17: 295-318Crossref Scopus (99) Google Scholar, 8Papi F. General aspects.in: Papi F. Animal Homing. Chapman and Hall, London1992: 1-18Crossref Google Scholar]. An animal translocated away from a site to which it is faithful (e.g., a breeding site) will most likely attempt to return to it, thus allowing the study of its navigational abilities in the field. In marine turtles, females typically display a strong fidelity to their nesting beach, where they faithfully return every few years from their residential feeding grounds, often located hundreds of kilometres away [9Miller J.D. Reproduction in sea turtles.in: Lutz P.L. Musick J.A. The Biology of Sea Turtles. CRC Press, Boca Raton, FL1997: 51-82Google Scholar, 10Luschi P. Hays G.C. Papi F. A review of long-distance movements by marine turtles, and the possible role of ocean currents.Oikos. 2003; 103: 293-302Crossref Scopus (189) Google Scholar]. Within a reproductive season, each turtle lays multiple clutches of eggs and remains in the waters close to the nesting beach between successive egg-laying events [9Miller J.D. Reproduction in sea turtles.in: Lutz P.L. Musick J.A. The Biology of Sea Turtles. CRC Press, Boca Raton, FL1997: 51-82Google Scholar]. Previous homing experiments showed that, when experimentally translocated early during their reproductive period, turtles tend to return to their nesting beach to complete their seasonal egg-laying cycle [7Girard C. Sudre J. Benhamou S. Roos D. Luschi P. Homing in green turtles Chelonia mydas: Oceanic currents act as a constraint rather than as an information source.Mar. Ecol. Prog. Ser. 2006; 322: 281-289Crossref Scopus (50) Google Scholar, 11Carr A. The case for long-range chemoreceptive piloting in Chelonia.in: Galler S.R. Schmidt-Koenig K. Jacobs G.J. Belleville R.E. Animal Orientation and Navigation. NASA SP-262, Washington, D.C1972: 469-483Google Scholar, 12Murphy T.M. Hopkins-Murphy S.R. Homing of translocated gravid loggerhead turtles.in: Richardson T.H. Richardson J.I. Donnelly M. Proceedings 10th Annual Symposium on Sea Turtle Biology and Conservation. NOAA Technical Memorandum NMFS-SEFC-278. National Oceanographic Atmospheric Administration, Miami, FL1990: 123-124Google Scholar, 13Luschi P. Papi F. Liew H.C. Chan E.H. Bonadonna F. Long-distance migration and homing after displacement in the green turtle (Chelonia mydas): A satellite tracking study.J. Comp. Physiol. 1996; 178A: 447-452Google Scholar, 14Papi F. Luschi P. Crosio E. Hughes G.R. Satellite tracking experiments on the navigational ability and migratory behaviour of the loggerhead turtle Caretta caretta.Mar. Biol. 1997; 129: 215-220Crossref Scopus (59) Google Scholar, 15Luschi P. Åkesson S. Broderick A.C. Glen F. Godley B.J. Papi F. Hays G.C. Testing the navigational abilities of ocean migrants: Displacement experiments on green sea turtles (Chelonia mydas).Behav. Ecol. Sociobiol. 2001; 50: 528-534Crossref Scopus (65) Google Scholar, 16Hays G.C. Åkesson S. Broderick A.C. Glen F. Godley B.J. Papi F. Luschi P. Island-finding ability of marine turtles.Proc. R. Soc. Lond. B. Biol. Sci. 2003; 270: 5-7Crossref Scopus (58) Google Scholar]. We employed this type of experiment to investigate the role of magnetic information in the homing abilities of green turtles nesting at Mayotte, the easternmost island of the Comoros archipelago in the Northern Mozambique Channel. Turtles were captured while ashore to nest at Saziley beach (12.98°S; 45.19°E), in the southeastern part of Mayotte, and were then translocated to four release sites northeast, southwest, and southeast of Saziley (see Table S1 in the Supplemental Data available online). Five releases of four turtles each were performed (Table 1), with three different treatments: turtles magnetically disturbed only during transportation to the release site (MT group, n = 6), turtles magnetically treated during the homing trip (MH group, n = 7), and controls (C group, n = 7). Magnetically disturbed turtles had powerful, mobile magnets attached to their head (Figure 1A) to induce a randomly varying magnetic field around it [17Bonadonna F. Bajzak C. Benhamou S. Igloi K. Jouventin P. Lipp H.-K. Dell'Omo G. Orientation in the wandering albatross: Interfering with magnetic perception does not affect orientation performance.Proc. R. Soc. Lond. B. Biol. Sci. 2005; 272: 489-495Crossref Scopus (68) Google Scholar]. Magnets were attached at the nesting beach (MT turtles) or on board just before release (MH turtles). MH turtles were therefore prevented from detecting geomagnetic cues during the homing process, whereas MT turtles were made unable to collect these cues during transportation. In this way, we investigated the relative importance of geomagnetic cues detected during transportation and during homing and aimed to assess the role of alternative navigational strategies potentially exploitable by homing turtles. If turtles were relying on a “magnetic map” to fix their position with respect to home (by comparing magnetic parameters detected at the release site with those memorized at the nesting beach [3Lohmann K.J. Lohmann C.M.F. Sea turtles, lobsters, and oceanic magnetic maps.Marine and Freshwater Behavior and Physiology. 2006; 39: 49-64Crossref Scopus (40) Google Scholar, 8Papi F. General aspects.in: Papi F. Animal Homing. Chapman and Hall, London1992: 1-18Crossref Google Scholar]), we expected that MH turtles only would have been affected by the treatment. If turtles paid attention to magnetic cues picked up en route (e.g., to monitor the direction of passive displacement), or if magnets produce some long-lasting after-effect on magnetic receptors, then MT turtles would have exhibited an impairment in homing.Table 1Homing Performances of the Three Turtle GroupsTurtle (CCL, cm)Release (Direction)Length of Homing Trip (km)Speed of Homing Trip (km/d)Straightness Index of Track PathStraightness Index of Motor PathC GROUPC1 (104)1 (SW)31029.90.340.35C2 (117)1 (SW)21441.40.390.59C3 (115)2 (NE)9050.00.690.72C4 (103)2 (NE)11643.70.580.85C5 (110)3 (SE)38510.60.190.44C6 (107)4 (SE)34826.50.280.42C7 (102)5 (SE)33414.10.260.71Mean ± SEM257 ± 4430.9 ± 5.70.39 ± 0.070.58 ± 0.07MH GROUPMH1 (103)1 (SW)39717.20.190.08MH2 (109)1 (SW)——−0.26−0.18MH3 (111)2 (NE)28517.00.240.54MH4 (107)2 (NE)9767.40.650.72MH5 (95)4 (SE)14356.80.050.03MH6 (107)4 (SE)40029.40.240.34MH7 (108)4 (SE)49227.10.190.25Mean ± SEM518 ± 19227.5 ± 8.10.19 ± 0.100.25 ± 0.12MT GROUPMT1 (110)3 (SE)7637.20.080.25MT2 (106)3 (SE)9148.20.070.00MT3 (105)3 (SE)37119.50.190.35MT4 (102)5 (SE)22144.40.040.05MT5 (108)5 (SE)69115.30.120.05MT6 (112)5 (SE)86118.50.110.09Mean ± SEM969 ± 26112.2 ± 2.60.10 ± 0.020.13 ± 0.06CCL = Curved Carapace Length. For turtle MH2, which stopped at Mohéli Island, homing-trip length and speed could not be calculated. See text for further explanations. Open table in a new tab CCL = Curved Carapace Length. For turtle MH2, which stopped at Mohéli Island, homing-trip length and speed could not be calculated. See text for further explanations. All displaced turtles but one returned to Mayotte in 2–29 days, with 18 of them later returning to Saziley beach. The only turtle that did not home (MH2) reached the coastal waters of Mohéli (another Comoros island 140 km westward of Mayotte) by following a straight path (Figure 1C) and remained there for the rest of the tracking period (83 days). Green turtles are known to frequent Mohéli, either to feed in its coastal waters or to breed in its beaches [18Frazier J. Marine turtles in the Seychelles and adjacent territories.in: Stoddart D.R. Biogeography and Ecology of the Seychelles Islands. Junk W. Publishers, The Hague, The Netherlands1984: 417-468Google Scholar], but it is unknown whether turtle MH2 nested there. Most homing routes were not immediately directed toward Mayotte, with turtles often exhibiting curved or looping paths before reaching their target (Figures 1B–1D). The majority of turtles approached the island from the northern quadrants, as is especially evident for the releases from the southeast. We first compared the homing performances of the three treatments by relying on track straightness index, which best represents the orientation efficiency of tracked paths [19Benhamou S. How to reliably estimate the tortuosity of an animal's path: straightness, sinuosity, or fractal dimension?.J. Theor. Biol. 2004; 229: 209-220Crossref PubMed Scopus (302) Google Scholar]. A one-way ANOVA revealed a significant (F = 3.82, p = 0.04) difference among the indexes of the three groups, and a post-hoc Tukey test showed that controls had a significantly (p < 0.05) higher mean index than the MT group but not the MH group, with no significant difference between magnetically treated groups. However, these straightness indexes, being directly derived from recorded tracks, do not take into account the possible deflecting action of ocean currents. They may consequently be unreliable if turtles do not compensate for current drift (i.e., if they are unable to anticipate the drift effects by adopting a heading that, albeit not immediately directed toward home, results in a movement leading to home with a shorter route when combined with drift action [20Green M. Alerstam T. The problem of estimating wind drift in migrating birds.J. Theor. Biol. 2002; 218: 485-496Crossref PubMed Scopus (48) Google Scholar]). Such an inability has actually been suggested by a pilot study conducted on three green turtles displaced from their breeding sites at Europa Island (southern Mozambique Channel [7Girard C. Sudre J. Benhamou S. Roos D. Luschi P. Homing in green turtles Chelonia mydas: Oceanic currents act as a constraint rather than as an information source.Mar. Ecol. Prog. Ser. 2006; 322: 281-289Crossref Scopus (50) Google Scholar]). It is worth noting that, in any case, homing turtles are assumed to have been able to correct for passive displacements (including current drift and the initial displacement by boat) by estimating the home direction along their homing journey. Their possible ability to compensate for the current drift is another, independent question (see [7Girard C. Sudre J. Benhamou S. Roos D. Luschi P. Homing in green turtles Chelonia mydas: Oceanic currents act as a constraint rather than as an information source.Mar. Ecol. Prog. Ser. 2006; 322: 281-289Crossref Scopus (50) Google Scholar] for a detailed discussion of this complex matter). To properly evaluate the turtles' homing abilities, we therefore estimated the ocean surface currents in the northern part of the Mozambique Channel (see Experimental Procedures for details) and assessed their mechanical impact on the turtles' homing journeys. During the tracking periods, currents were quite variable in time and space and were mainly linked to the occurrence of local sea-level anomalies and associated eddies. The turtles' behavior in relation to these currents was variable too: in some cases, the turtles' movement was directed against the current flow, whereas in other instances the turtles tended to follow the currents (Figure 2 and Movie S1 in the Supplemental Data available online). This latter behavior was especially evident in the 2005 releases when some turtles moved in fair accordance with the substantial currents associated with a large anticyclonic eddy (Figure 2B) during long parts of their homing trips. The quantitative estimation of surface current velocities allowed us to remove the current contribution to the recorded (ground-related) movement of each turtle and thus to compute the water-related heading vectors, which represent the swimming movements actually made by the turtles in the various phases of their homing trip ([7Girard C. Sudre J. Benhamou S. Roos D. Luschi P. Homing in green turtles Chelonia mydas: Oceanic currents act as a constraint rather than as an information source.Mar. Ecol. Prog. Ser. 2006; 322: 281-289Crossref Scopus (50) Google Scholar], see inset in Figure 2B]. The sequence of heading vectors obtained in this way for each turtle's ground-related path constitutes a corresponding water-related “motor path” (Figure S1). Mean current speeds along the tracks ranged between 12.6 and 32.2 cm/s, whereas turtles were found to swim 1.7–5.4 times faster than this (current contribution excluded). The movements recorded were therefore largely determined by the turtles' active swimming. Computer simulations of the movements of virtual turtles passively drifting within the same current field as the experimental individuals indicate that no drifting turtle could have reached Mayotte within one month after release [21Girard, C. 2005. Etude du comportement d'orientation d'espèces pélagiques tropicales vis-à-vis d'attracteurs. PhD thesis, University of La Réunion.Google Scholar]. We then evaluated turtles' ability to compensate for current drift by comparing the homeward components of the calculated track and heading vectors for single turtles; if a turtle indeed compensated for drift, its motor path would have been less homeward oriented than its track path, with the opposite occurring in the absence of drift compensation. Such within-subject comparisons of homeward components (in subsampled datasets to allow for statistical independence; see Experimental Procedures) were performed on six of the seven control turtles (there was not enough data for the remaining one; this procedure was not applied to MT and MH turtles because magnet application may have prevented them from determining the home direction). They revealed that the mean homeward component of the track path was significantly lower than that of the corresponding motor path in all cases (Wilcoxon signed rank tests: p < 0.05 or less). This result confirms the conclusion of our previous study on three green turtles [7Girard C. Sudre J. Benhamou S. Roos D. Luschi P. Homing in green turtles Chelonia mydas: Oceanic currents act as a constraint rather than as an information source.Mar. Ecol. Prog. Ser. 2006; 322: 281-289Crossref Scopus (50) Google Scholar]: Considered individually, none of them was able to compensate for the current drift. To further investigate this issue, we performed a supplemental interindividual analysis by comparing the straightness indexes of each turtle's track and motor paths in the seven control turtles. These indexes turned out to be significantly higher for motor, water-related paths than for track, ground-related paths (Wilcoxon signed rank test, T+ = 28, p < 0.02), confirming at the population level that the orientation efficiency of motor paths is higher than that of track paths. Because motor paths better represent the turtles' intended movements than track paths, the three experimental groups were then compared on the basis of the straightness indexes of the single motor paths instead of those of the track paths previously used (Table 1). A one-way ANOVA revealed a highly significant (F = 7.02; p = 0.006) difference among the three groups, with control turtles performing significantly better (p < 0.05; Tukey test) than both magnetically treated groups, whose performances did not differ significantly from each other. Furthermore, we considered that a statistical bias may have been introduced in our global analysis by the fact that, for logistical reasons, MT turtles were all released at the same site. We therefore performed additional two-sample tests on motor-path indexes by considering MT and MH turtles separately. Mann-Whitney tests revealed a significant difference between C and MH turtles (when all releases were considered; U = 8.5, p < 0.04) and between MT turtles and the three controls released at the southeast site (U = 0; p < 0.025). Thus, these tests independently confirmed the outcome of the global analysis and showed that the effects previously highlighted were not due to a release-site bias. Despite the small sample size, the experiment yielded statistically significant evidence for both track and motor straightness indexes and showed a worsening in the homing abilities of both experimental groups after the experimental displacement from their nesting beach. Magnetic treatment en route was as effective as magnet application prior to release; the homing performances of the MT turtles were not significantly different from those of the MH turtles. According to these findings, magnetic cues play a role in sea-turtle homing. It is difficult to determine the actual magnetic-field alteration produced by the attached magnets (given that they were randomly oscillating), but it can be safely estimated that they produced a disturbance of at least 200 μT around the whole turtle head [6Papi F. Luschi P. Åkesson S. Capogrossi S. Hays G.C. Open-sea migration of magnetically disturbed sea turtles.J. Exp. Biol. 2000; 203: 3435-3443PubMed Google Scholar], where all the putative magnetoreception sites (e.g., trigeminal nerve, eye, and pineal gland) are located [22Wiltschko W. Wiltschko R. Magnetic orientation and magnetoreception in birds and other animals.J. Comp. Physiol. 2005; 191A: 675-693Crossref Scopus (373) Google Scholar, 23Johnsen S. Lohmann K.J. The physics and neurobiology of magnetoreception.Nat. Rev. Neurosci. 2005; 6: 703-712Crossref PubMed Scopus (273) Google Scholar]. The treatment therefore prevented the turtles from correctly detecting the Earth's magnetic field (whose total intensity is about 33 μT in the Mayotte area; Table S1), making reliance on both a magnetic compass and location sense impossible (see [24Mouritsen H. Huyvaert K.P. Frost B.J. Anderson D.J. Waved albatrosses can navigate with strong magnets attached to their head.J. Exp. Biol. 2003; 206: 4155-4166Crossref PubMed Scopus (51) Google Scholar] for a detailed presentation of the navigational impairments produced by magnet application). Attachment of (less powerful) magnets was indeed effective in disturbing the orientation of hatchling loggerhead turtles in arena tests, a response that could have derived either from an effect on a compass or from an effect on a position-finding mechanism, or both ([25Irwin W.P. Lohmann K.J. Magnet-induced disorientation in hatchling loggerhead sea turtles.J. Exp. Biol. 2003; 206: 497-501Crossref PubMed Scopus (23) Google Scholar]; see also [26Baldwin H.A. Long-range radio tracking of sea turtles and polar bear—Instrumentation and preliminary results.in: Galler S.R. Schmidt-Koenig K. Jacobs G.J. Belleville R.E. Animal Orientation and Navigation. NASA SP-262, Washington, D.C1972: 19-35Google Scholar] for preliminary experiments on magnet-equipped adult turtles). At present, it is difficult to understand how geomagnetic information is implemented in the turtles' navigational system or to assess which magnetic parameters (especially intensity and/or inclination [3Lohmann K.J. Lohmann C.M.F. Sea turtles, lobsters, and oceanic magnetic maps.Marine and Freshwater Behavior and Physiology. 2006; 39: 49-64Crossref Scopus (40) Google Scholar, 27Lohmann K.J. Lohmann C.M.F. Detection of magnetic field intensity by sea turtles.Nature. 1996; 380: 59-61Crossref Scopus (177) Google Scholar]) are involved in these processes. Magnet attachment does not make it possible to produce specific magnetic-field alterations detected by the treated animal. Because the location and the functioning of the putative magnetoreceptor are still debated, the artificial field actually produced at that site cannot be predicted. The most immediate way by which displaced turtles may exploit magnetic cues would be to rely on some kind of “magnetic map” [2Bingman V.P. Cheng K. Mechanisms of animal global navigation: Comparative perspectives and enduring challenges.Ethology, Ecology, and Evolution. 2006; 17: 295-318Crossref Scopus (99) Google Scholar, 3Lohmann K.J. Lohmann C.M.F. Sea turtles, lobsters, and oceanic magnetic maps.Marine and Freshwater Behavior and Physiology. 2006; 39: 49-64Crossref Scopus (40) Google Scholar, 8Papi F. General aspects.in: Papi F. Animal Homing. Chapman and Hall, London1992: 1-18Crossref Google Scholar, 28Able K.P. The concepts and terminology of bird navigation.J. Avian Biol. 2001; 32: 174-183Crossref Scopus (58) Google Scholar, 29Lohmann K.J. Hester J.T. Lohmann C.M.F. Long-distance navigation in sea turtles.Ethology, Ecology, and Evolution. 1999; 11: 1-23Crossref Scopus (90) Google Scholar]. For instance, newborn loggerhead turtles and juvenile green turtles have been shown to detect differences in magnetic-field intensity and inclination and to display appropriate orientation responses in arenas when they are presented with these two parameters in specific combinations that simulate long-distance translocations [4Lohmann K.J. Lohmann C.M.F. Ehrhart L.M. Bagley D.A. Swing T. Geomagnetic map used in sea-turtle navigation.Nature. 2004; 428: 909-910Crossref PubMed Scopus (207) Google Scholar, 30Lohmann K.J. Cain S.D. Dodge S.A. Lohmann C.M.F. Regional magnetic fields as navigational markers for sea turtles.Science. 2001; 294: 364-366Crossref PubMed Scopus (188) Google Scholar]. At least for juvenile green turtles, these results have been interpreted as indications of reliance on navigational magnetic maps, possibly at a coarse resolution [3Lohmann K.J. Lohmann C.M.F. Sea turtles, lobsters, and oceanic magnetic maps.Marine and Freshwater Behavior and Physiology. 2006; 39: 49-64Crossref Scopus (40) Google Scholar, 4Lohmann K.J. Lohmann C.M.F. Ehrhart L.M. Bagley D.A. Swing T. Geomagnetic map used in sea-turtle navigation.Nature. 2004; 428: 909-910Crossref PubMed Scopus (207) Google Scholar]. In the Mozambique Channel area, magnetic-field conditions are indeed quite favorable for reliance on such a magnetic map because inclination and intensity gradients are quite uniform and intersect each other at wide angles so that they form a grid potentially suitable for navigation (data from IGRF model, see also [29Lohmann K.J. Hester J.T. Lohmann C.M.F. Long-distance navigation in sea turtles.Ethology, Ecology, and Evolution. 1999; 11: 1-23Crossref Scopus (90) Google Scholar]). The behavior of the MH turtles is in accordance with such a mechanism; displaced turtles that use magnetic information would be greatly affected by magnet attachment at the release site in that they would be unable to properly evaluate the geomagnetic parameters after release and hence would be unable to establish their present location in relation to home. Our results, however, do not allow us to determine whether the effect recorded in the MH turtles is only due to a disturbance of their location-fixing mechanism because a similar impairment would have also been recorded if the MH turtles were relying on nonmagnetic positional information and on a magnetic compass to determine the home direction. Conversely, the impairment shown by the MT turtles, which were treated only during transportation to the release site, is not directly explainable by an effect on a navigational mechanism based on geomagnetic cues detected during homing. These turtles were not wearing magnets during their homing trip, and so they should have been able to collect positional information while homing (at the latest after recovering from the treatment), whereas they were as disturbed as the MH turtles. This rather surprising finding indicates a possible navigational role of geomagnetic information collected during (passive) transportation; this information may have provided untreated turtles with some indications on the displacement direction [28Able K.P. The concepts and terminology of bird navigation.J. Avian Biol. 2001; 32: 174-183Crossref Scopus (58) Google Scholar]. For instance, displaced turtles might have sensed swell-induced accelerations of the boat and have consequently assessed, at least crudely, the general direction of travelling with respect to their magnetic compass. Such a reliance on navigational information collected during passive transportation is actually known for pigeons; in these birds the ability is based on olfactory cues [31Wallraff H.G. Avian Navigation: Pigeon Homing as a Paradigm. Springer Verlag, Berlin2005Google Scholar], but a complementary role of compass magnetic information has also been proposed ([32Wiltschko R. Wiltschko W. Pigeon homing: Change in navigational strategy during" @default.
• W2150126293 created "2016-06-24" @default.
• W2150126293 creator A5019700384 @default.
• W2150126293 creator A5034404322 @default.
• W2150126293 creator A5037778815 @default.
• W2150126293 creator A5072039010 @default.
• W2150126293 creator A5080030965 @default.
• W2150126293 creator A5083121771 @default.
• W2150126293 creator A5084328421 @default.
• W2150126293 date "2007-01-01" @default.
• W2150126293 modified "2023-10-18" @default.
• W2150126293 title "Marine Turtles Use Geomagnetic Cues during Open-Sea Homing" @default.
• W2150126293 cites W135426905 @default.
• W2150126293 cites W1965216694 @default.
• W2150126293 cites W1972485929 @default.
• W2150126293 cites W1978201754 @default.
• W2150126293 cites W1980328666 @default.
• W2150126293 cites W1984592609 @default.
• W2150126293 cites W2005570802 @default.
• W2150126293 cites W2010572349 @default.
• W2150126293 cites W2012418482 @default.
• W2150126293 cites W2019330298 @default.
• W2150126293 cites W2037565640 @default.
• W2150126293 cites W2043124831 @default.
• W2150126293 cites W2052935129 @default.
• W2150126293 cites W2079500075 @default.
• W2150126293 cites W2092434691 @default.
• W2150126293 cites W2096331940 @default.
• W2150126293 cites W2108693880 @default.
• W2150126293 cites W2109134282 @default.
• W2150126293 cites W2118129830 @default.
• W2150126293 cites W2120886493 @default.
• W2150126293 cites W2125449264 @default.
• W2150126293 cites W2136623215 @default.
• W2150126293 cites W2146373465 @default.
• W2150126293 cites W2162015929 @default.
• W2150126293 cites W2169756236 @default.
• W2150126293 cites W2172255898 @default.
• W2150126293 cites W4205159396 @default.
• W2150126293 doi "https://doi.org/10.1016/j.cub.2006.11.062" @default.
• W2150126293 hasPubMedId "https://pubmed.ncbi.nlm.nih.gov/17240337" @default.
• W2150126293 hasPublicationYear "2007" @default.
• W2150126293 type Work @default.
• W2150126293 sameAs 2150126293 @default.
• W2150126293 citedByCount "103" @default.
• W2150126293 countsByYear W21501262932012 @default.
• W2150126293 countsByYear W21501262932013 @default.
• W2150126293 countsByYear W21501262932014 @default.
• W2150126293 countsByYear W21501262932015 @default.
• W2150126293 countsByYear W21501262932016 @default.
• W2150126293 countsByYear W21501262932017 @default.
• W2150126293 countsByYear W21501262932018 @default.
• W2150126293 countsByYear W21501262932019 @default.
• W2150126293 countsByYear W21501262932020 @default.
• W2150126293 countsByYear W21501262932021 @default.
• W2150126293 countsByYear W21501262932022 @default.
• W2150126293 countsByYear W21501262932023 @default.
• W2150126293 crossrefType "journal-article" @default.
• W2150126293 hasAuthorship W2150126293A5019700384 @default.
• W2150126293 hasAuthorship W2150126293A5034404322 @default.
• W2150126293 hasAuthorship W2150126293A5037778815 @default.
• W2150126293 hasAuthorship W2150126293A5072039010 @default.
• W2150126293 hasAuthorship W2150126293A5080030965 @default.
• W2150126293 hasAuthorship W2150126293A5083121771 @default.
• W2150126293 hasAuthorship W2150126293A5084328421 @default.
• W2150126293 hasBestOaLocation W21501262931 @default.
• W2150126293 hasConcept C111368507 @default.
• W2150126293 hasConcept C111370547 @default.
• W2150126293 hasConcept C115260700 @default.
• W2150126293 hasConcept C121332964 @default.
• W2150126293 hasConcept C127313418 @default.
• W2150126293 hasConcept C151872237 @default.
• W2150126293 hasConcept C169760540 @default.
• W2150126293 hasConcept C18903297 @default.
• W2150126293 hasConcept C199635899 @default.
• W2150126293 hasConcept C2909151806 @default.
• W2150126293 hasConcept C2992026346 @default.
• W2150126293 hasConcept C62520636 @default.
• W2150126293 hasConcept C86803240 @default.
• W2150126293 hasConcept C90856448 @default.
• W2150126293 hasConceptScore W2150126293C111368507 @default.
• W2150126293 hasConceptScore W2150126293C111370547 @default.
• W2150126293 hasConceptScore W2150126293C115260700 @default.
• W2150126293 hasConceptScore W2150126293C121332964 @default.
• W2150126293 hasConceptScore W2150126293C127313418 @default.
• W2150126293 hasConceptScore W2150126293C151872237 @default.
• W2150126293 hasConceptScore W2150126293C169760540 @default.
• W2150126293 hasConceptScore W2150126293C18903297 @default.
• W2150126293 hasConceptScore W2150126293C199635899 @default.
• W2150126293 hasConceptScore W2150126293C2909151806 @default.
• W2150126293 hasConceptScore W2150126293C2992026346 @default.
• W2150126293 hasConceptScore W2150126293C62520636 @default.
• W2150126293 hasConceptScore W2150126293C86803240 @default.
• W2150126293 hasConceptScore W2150126293C90856448 @default.
• W2150126293 hasIssue "2" @default.
• W2150126293 hasLocation W21501262931 @default.
• W2150126293 hasLocation W21501262932 @default.
• W2150126293 hasLocation W21501262933 @default.

• next