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Open Access Publications from the University of California

Scholarly Works (2 results)

  • Article
  • Peer Reviewed
UC San Diego Previously Published Works (2016)
Background: A characterization of an organism's thermoregulatory ability informs our understanding of its physiology, ecology and behavior. Biotelemetry studies on thermoregulation increasingly rely on in situ body temperature measurements from surgically implanted data loggers. To protect the organism and the instrument, the electronics and the temperature sensor are often encased in non-conductive materials prior to insertion into the organism. These materials thermally insulate the sensor, thus potentially biasing temperature measurements to suggest a greater degree of thermoregulation than is actually the case. Results: Here we present methodology to quantify and correct for the effect of sensor coatings on temperature measurements by data recording tags. We illustrate these methods using Wildlife Computer's Mk9 archival tag, field data from the peritoneal cavity of a juvenile albacore tuna (Thunnus alalunga) and simulated data of several species of ectotherms (fish: Hemitripterus americanus, Catostomus commersoni and Maxostoma macrolepidotum; reptiles: Macroclemys temminckii, Varanus spp.), ranging in size from 10 to 1000 g. Mk9 tags had rate constants (measures of the sensor's ability to respond to changes in temperature) of 1.79 ± 0.06 and 0.81 ± 0.07 min-1 for the external and internal sensors, respectively. The higher rate constant of the external sensor produced smaller errors than the internal sensor. Yet, both sensors produced instantaneous errors of over 1 °C for all species tested, with the exception of T. alalunga. Conclusions: The effect of sensor coatings on body temperature measurements is shown to depend on the relative values of the sensor's and the organism's rate constant and the rate of change of environmental temperature. If the sensor's rate constant is lower than that of the organism, the temperature measurements will reflect the thermal properties of the sensor rather than the organism.
    Cover page: Quantifying the effects of sensor coatings on body temperature measurements
    • Thesis
    • Peer Reviewed
    UC San Diego Electronic Theses and Dissertations (2016)

    Characterization of an animal’s movement patterns and the motivations behind those movements can allow us to predict their response to changes in the environment or ecosystem. In my thesis, I use biotelemetry data and mechanistic models to investigate the movements of albacore tuna within the context of their thermal biology as they move through a dynamic and heterogeneous thermal environment. My results indicate that albacore have thermal habitat constraints dictated by their inability to maintain a functional body temperature in SST below 11 °C, and high behavioral and physiological costs at SST above 20 °C. I show that albacore migrations are longer and have more consistent phenology and direction when fish are migrating between habitats whose sea surface temperatures trend below 13ºC and above 20 ºC. Albacore time their migrations with annual changes in the temperatures of their origins and destinations. I also show that thermal fronts serve as a dual resource to albacore. I characterize the movement of four tunas as they utilize sub-mesoscale features associated with a thermal front. For two weeks, the tunas swam between the warmest and coldest available waters, making on average 50 trips across the front per day, with 85% of these occurring during daytime. The use of the warm side of the front resulted in an increase in body temperature, and the strength of the front was directly correlated with foraging success. This work provides the necessary parameters to model albacore movement and a mechanistic understanding of the limits to albacore distribution.

      Cover page: Navigating a seascape: physiological and environmental motivations behind juvenile North Pacific albacore movement patterns
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