A new non-invasive attachment technique to measure heat flux in cetaceans

While biologging research on marine mammals has made considerable advances in sensory, behavioral, and geolocation monitoring over the past 40 years using small electronic sensors, the thermal physiology of diving marine mammals—especially how they regulate excess heat—is comparatively poorly documented. This is especially true for many cetacean species due to technological challenges associated with sensor interference with heat transfer properties across the skin. To address this, we developed a customized biologger capable of collecting concurrent information on the behavior (activity levels, dive depth) and thermal physiology (heat flux) of adult bottlenose dolphins ( Tursiops truncatus ). We designed a customized heat flux sensor and embedded it into a non-invasive, novel silicone suction cup attachment system, allowing for instantaneous and continuous heat flux measurements across the skin of the swimming and diving cetaceans. The tag (including recorder and sensor attachment system) was tested on trained bottlenose dolphins and demonstrated its promise for short-term deployments. This new device will enable an improved understanding of cetacean thermal biology and its potential role in the ability to respond to changes in sea temperature due to climate change.