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Aquatic Biology

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AB 3:265-270 (2008)  -  DOI:

Effect of ocean current on the dead-reckoning estimation of 3-D dive paths of emperor penguins

Kozue Shiomi1,*, Katsufumi Sato2, Hiromichi Mitamura1, Nobuaki Arai1, Yasuhiko Naito3, Paul J. Ponganis4

1Department of Social Informatics, Graduate School of Informatics, Kyoto University, Kyoto 606-8501, Japan
2International Coastal Research Center, Ocean Research Institute, University of Tokyo, 2-106-1 Akahama, Otsuchi, Iwate, 012-1102, Japan
3National Institute of Polar Research, 1-9-10, Kaga, Itabashi, Tokyo 173-8515, Japan
4Center for Marine Biotechnology and Biomedicine, Scripps Institution of Oceanography, University of California San Diego, La Jolla, California 92093-0204, USA

ABSTRACT: The dead-reckoning technique is a useful method for obtaining 3-D movement data of aquatic animals. However, such positional data include an accumulative error. Understanding the source of the error is important for proper data interpretation. In order to determine whether ocean currents affect dive paths calculated by dead-reckoning, as has previously been hypothesized, we examined the directions of the estimated positions relative to the known real points (error direction) and the relationship between the error direction and the current direction. 3-D dive paths of emperor penguins Aptenodytes forsteri diving at isolated dive holes in eastern McMurdo Sound were reconstructed by dead-reckoning, and the net error and error direction were calculated. The net error correlated positively with the dive duration. The error directions were not distributed uniformly, and the mean error direction tended to be north of the starting point of dives. Because there was a southward-flowing current in eastern McMurdo Sound, the ocean current was likely to affect the calculated dive paths. Therefore, the method of error correction generally used, in which the net error divided by the dive duration is applied to each estimated position, is realistically appropriate, provided that the current does not change significantly during a dive.

KEY WORDS: 3-D dive path · Dead-reckoning · Ocean current · Error direction · Emperor penguin · Data logger

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Cite this article as: Shiomi K, Sato K, Mitamura H, Arai N, Naito Y, Ponganis PJ (2008) Effect of ocean current on the dead-reckoning estimation of 3-D dive paths of emperor penguins. Aquat Biol 3:265-270.

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