Bio

Professional Education


  • Bachelor of Science, Swansea University, Marine Biology (2007)
  • Doctor of Philosophy, Swansea University (2011)

Stanford Advisors


Publications

Journal Articles


  • Contrasting diel patterns in vertical movement and locomotor activity of whale sharks at Ningaloo Reef MARINE BIOLOGY Gleiss, A. C., Wright, S., Liebsch, N., Wilson, R. P., Norman, B. 2013; 160 (11): 2981-2992
  • Does prey size matter? Novel observations of feeding in the leatherback turtle (Dermochelys coriacea) allow a test of predator-prey size relationships BIOLOGY LETTERS Fossette, S., Gleiss, A. C., Casey, J. P., Lewis, A. R., Hays, G. C. 2012; 8 (3): 351-354

    Abstract

    Optimal foraging models predict that large predators should concentrate on large prey in order to maximize their net gain of energy intake. Here, we show that the largest species of sea turtle, Dermochelys coriacea, does not strictly adhere to this general pattern. Field observations combined with a theoretical model suggest that a 300 kg leatherback turtle would meet its energetic requirements by feeding for 3-4 h a day on 4 g jellyfish, but only if prey were aggregated in high-density patches. Therefore, prey abundance rather than prey size may, in some cases, be the overriding parameter for foraging leatherbacks. This is a classic example where the presence of small prey in the diet of a large marine predator may reflect profitable foraging decisions if the relatively low energy intake per small individual prey is offset by high encounter rates and minimal capture and handling costs. This study provides, to our knowledge, the first quantitative estimates of intake rate for this species.

    View details for DOI 10.1098/rsbl.2011.0965

    View details for Web of Science ID 000303933300010

    View details for PubMedID 22090203

  • Tri-Axial Dynamic Acceleration as a Proxy for Animal Energy Expenditure; Should We Be Summing Values or Calculating the Vector? PLOS ONE Qasem, L., Cardew, A., Wilson, A., Griffiths, I., Halsey, L. G., Shepard, E. L., Gleiss, A. C., Wilson, R. 2012; 7 (2)

    Abstract

    Dynamic body acceleration (DBA) has been used as a proxy for energy expenditure in logger-equipped animals, with researchers summing the acceleration (overall dynamic body acceleration--ODBA) from the three orthogonal axes of devices. The vector of the dynamic body acceleration (VeDBA) may be a better proxy so this study compared ODBA and VeDBA as proxies for rate of oxygen consumption using humans and 6 other species. Twenty-one humans on a treadmill ran at different speeds while equipped with two loggers, one in a straight orientation and the other skewed, while rate of oxygen consumption (VO2) was recorded. Similar data were obtained from animals but using only one (straight) logger. In humans, both ODBA and VeDBA were good proxies for VO2 with all r(2) values exceeding 0.88, although ODBA accounted for slightly but significantly more of the variation in VO2 than did VeDBA (P<0.03). There were no significant differences between ODBA and VeDBA in terms of the change in VO2 estimated by the acceleration data in a simulated situation of the logger being mounted straight but then becoming skewed (P = 0.744). In the animal study, ODBA and VeDBA were again good proxies for VO2 with all r(2) values exceeding 0.70 although, again, ODBA accounted for slightly, but significantly, more of the variation in VO2 than did VeDBA (P<0.03). The simultaneous contraction of muscles, inserted variously for limb stability, may produce muscle oxygen use that at least partially equates with summing components to derive DBA. Thus, a vectorial summation to derive DBA cannot be assumed to be the more 'correct' calculation. However, although within the limitations of our simple study, ODBA appears a marginally better proxy for VO2. In the unusual situation where researchers are unable to guarantee at least reasonably consistent device orientation, they should use VeDBA as a proxy for VO2.

    View details for DOI 10.1371/journal.pone.0031187

    View details for Web of Science ID 000302853600123

    View details for PubMedID 22363576

  • High activity and Levy searches: jellyfish can search the water column like fish PROCEEDINGS OF THE ROYAL SOCIETY B-BIOLOGICAL SCIENCES Hays, G. C., Bastian, T., Doyle, T. K., Fossette, S., Gleiss, A. C., Gravenor, M. B., Hobson, V. J., Humphries, N. E., Lilley, M. K., Pade, N. G., Sims, D. W. 2012; 279 (1728): 465-473

    Abstract

    Over-fishing may lead to a decrease in fish abundance and a proliferation of jellyfish. Active movements and prey search might be thought to provide a competitive advantage for fish, but here we use data-loggers to show that the frequently occurring coastal jellyfish (Rhizostoma octopus) does not simply passively drift to encounter prey. Jellyfish (327 days of data from 25 jellyfish with depth collected every 1 min) showed very dynamic vertical movements, with their integrated vertical movement averaging 619.2 m d(-1), more than 60 times the water depth where they were tagged. The majority of movement patterns were best approximated by exponential models describing normal random walks. However, jellyfish also showed switching behaviour from exponential patterns to patterns best fitted by a truncated Lévy distribution with exponents (mean μ=1.96, range 1.2-2.9) close to the theoretical optimum for searching for sparse prey (μopt≈2.0). Complex movements in these 'simple' animals may help jellyfish to compete effectively with fish for plankton prey, which may enhance their ability to increase in dominance in perturbed ocean systems.

    View details for DOI 10.1098/rspb.2011.0978

    View details for Web of Science ID 000298661700007

    View details for PubMedID 21752825

  • Moved by that sinking feeling: variable diving geometry underlies movement strategies in whale sharks FUNCTIONAL ECOLOGY Gleiss, A. C., Norman, B., Wilson, R. P. 2011; 25 (3): 595-607
  • Convergent evolution in locomotory patterns of flying and swimming animals NATURE COMMUNICATIONS Gleiss, A. C., Jorgensen, S. J., Liebsch, N., Sala, J. E., Norman, B., Hays, G. C., Quintana, F., Grundy, E., Campagna, C., Trites, A. W., Block, B. A., Wilson, R. P. 2011; 2

    Abstract

    Locomotion is one of the major energetic costs faced by animals and various strategies have evolved to reduce its cost. Birds use interspersed periods of flapping and gliding to reduce the mechanical requirements of level flight while undergoing cyclical changes in flight altitude, known as undulating flight. Here we equipped free-ranging marine vertebrates with accelerometers and demonstrate that gait patterns resembling undulating flight occur in four marine vertebrate species comprising sharks and pinnipeds. Both sharks and pinnipeds display intermittent gliding interspersed with powered locomotion. We suggest, that the convergent use of similar gait patterns by distinct groups of animals points to universal physical and physiological principles that operate beyond taxonomic limits and shape common solutions to increase energetic efficiency. Energetically expensive large-scale migrations performed by many vertebrates provide common selection pressure for efficient locomotion, with potential for the convergence of locomotory strategies by a wide variety of species.

    View details for DOI 10.1038/ncomms1350

    View details for Web of Science ID 000294804400018

    View details for PubMedID 21673673

  • Making overall dynamic body acceleration work: on the theory of acceleration as a proxy for energy expenditure METHODS IN ECOLOGY AND EVOLUTION Gleiss, A. C., Wilson, R. P., Shepard, E. L. 2011; 2 (1): 23-33
  • Behaviour and buoyancy regulation in the deepest-diving reptile: the leatherback turtle JOURNAL OF EXPERIMENTAL BIOLOGY Fossette, S., Gleiss, A. C., Myers, A. E., Garner, S., Liebsch, N., Whitney, N. M., Hays, G. C., Wilson, R. P., Lutcavage, M. E. 2010; 213 (23): 4074-4083

    Abstract

    In the face of the physical and physiological challenges of performing breath-hold deep dives, marine vertebrates have evolved different strategies. Although behavioural strategies in marine mammals and seabirds have been investigated in detail, little is known about the deepest-diving reptile - the leatherback turtle (Dermochelys coriacea). Here, we deployed tri-axial accelerometers on female leatherbacks nesting on St Croix, US Virgin Islands, to explore their diving strategy. Our results show a consistent behavioural pattern within dives among individuals, with an initial period of active swimming at relatively steep descent angles (∼-40 deg), with a stroke frequency of 0.32 Hz, followed by a gliding phase. The depth at which the gliding phase began increased with the maximum depth of the dives. In addition, descent body angles and vertical velocities were higher during deeper dives. Leatherbacks might thus regulate their inspired air-volume according to the intended dive depth, similar to hard-shelled turtles and penguins. During the ascent, turtles actively swam with a stroke frequency of 0.30 Hz but with a low vertical velocity (∼0.40 ms(-1)) and a low pitch angle (∼+26 deg). Turtles might avoid succumbing to decompression sickness ('the bends') by ascending slowly to the surface. In addition, we suggest that the low body temperature of this marine ectotherm compared with that of endotherms might help reduce the risk of bubble formation by increasing the solubility of nitrogen in the blood. This physiological advantage, coupled with several behavioural and physical adaptations, might explain the particular ecological niche the leatherback turtle occupies among marine reptiles.

    View details for DOI 10.1242/jeb.048207

    View details for Web of Science ID 000284146400024

    View details for PubMedID 21075949

  • Accelerating estimates of activity-specific metabolic rate in fishes: Testing the applicability of acceleration data-loggers JOURNAL OF EXPERIMENTAL MARINE BIOLOGY AND ECOLOGY Gleiss, A. C., Dale, J. J., Holland, K. N., Wilson, R. P. 2010; 385 (1-2): 85-91
  • A new prospect for tagging large free-swimming sharks with motion-sensitive data-loggers FISHERIES RESEARCH Gleiss, A. C., Norman, B., Liebsch, N., Francis, C., Wilson, R. P. 2009; 97 (1-2): 11-16
  • Derivation of body motion via appropriate smoothing of acceleration data AQUATIC BIOLOGY Shepard, E. L., Wilson, R. P., Halsey, L. G., Quintana, F., Gomez Laich, A., Gleiss, A. C., Liebsch, N., Myers, A. E., Norman, B. 2009; 4 (3): 235-241

    View details for DOI 10.3354/ab00104

    View details for Web of Science ID 000263642500003

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