We are pleased to announce a new publication in the Journal of Experimental Biology: Julie M. van der Hoop, Andreas Fahlman, Thomas Hurst, Julie Rocho-Levine, K. Alex Shorter, Victor Petrov and Michael J. Moore. Bottlenose dolphins modify behavior to reduce metabolic effect of tag attachment. J Exp Biol 2014 217:4229-4236. First posted online October 16, 2014, doi:10.1242/jeb.108225 The paper is available online: http://jeb.biologists.org/content/217/23/4229.abstract Please contact me if you would like a copy and do not otherwise have access to the pdf: jvanderhoop@whoi.edu Abstract: Attaching bio-telemetry or -logging devices (‘tags’) to marine animals for research and monitoring adds drag to streamlined bodies, thus affecting posture, swimming gaits and energy balance. These costs have never been measured in free-swimming cetaceans. To examine the effect of drag from a tag on metabolic rate, cost of transport and swimming behavior, four captive male dolphins (Tursiops truncatus) were trained to swim a set course, either non-tagged (n=7) or fitted with a tag (DTAG2; n=12), and surface exclusively in a flow-through respirometer in which oxygen consumption () and carbon dioxide production (; ml kg−1 min−1) rates were measured and respiratory exchange ratio (/) was calculated. Tags did not significantly affect individual mass-specific oxygen consumption, physical activity ratios (exercise /resting ), total or net cost of transport (COT; J m−1 kg−1) or locomotor costs during swimming or two-minute recovery phases. However, individuals swam significantly slower when tagged (by ~11%; mean ± s.d., 3.31±0.35 m s−1) than when non-tagged (3.73±0.41 m s−1). A combined theoretical and computational fluid dynamics model estimating drag forces and power exertion during swimming suggests that drag loading and energy consumption are reduced at lower swimming speeds. Bottlenose dolphins in the specific swimming task in this experiment slowed to the point where the tag yielded no increases in drag or power, while showing no difference in metabolic parameters when instrumented with a DTAG2. These results, and our observations, suggest that animals modify their behavior to maintain metabolic output and energy expenditure when faced with tag-induced drag. ---------------------------------------------------------- Julie van der Hoop PhD Candidate MIT-WHOI Joint Program in Oceanography Woods Hole MA 02543 http://www.whoi.edu/profile/jvanderhoop/
