Data-processing artefacts in three-dimensional dive path reconstruction from geomagnetic and acceleration data

Kozue Shiomi, Tomoko Narazaki, Katsufumi Sato, Kenichiro Shimatani, Nobuaki Arai, Paul J. Ponganis, Nobuyuki Miyazaki

Research output: Contribution to journalArticlepeer-review

31 Citations (Scopus)

Abstract

Tri-axis magnetism and acceleration data loggers have recently been used to obtain time-series headings and, consequently, the 3-dimensional dive paths of aquatic animals. However, problems may arise in the resulting calculation process with multiple parameters. In this study, the dive paths of loggerhead turtles and emperor penguins were reconstructed. For both species, apparently unrealistic movements were found. Time-series heading data of turtles showed small regular fluctuations synchronous with stroking. In the dive paths of penguins, infrequent abrupt changes in heading were observed during stroke cycles. These were unlikely to represent true behaviours according to observations of underwater behaviour and tri-axis magnetism and acceleration data. Based on the relationship between sampling frequency and frequency of body posture change, we suggest that (1) the changes in the animals' posture concurrent with strokes and (2) the mismatched treatment (i.e. filtering and non-filtering) of the acceleration and magnetism data caused the artefacts. These inferences are supported by the results of simulations. For data sets obtained at a given sampling frequency, the error pattern in calculated dive paths is likely to differ depending on the frequency and amplitude of body posture changes and in swim speed. In order to avoid misinterpretation, it is necessary to understand the assumptions and inherent problems of the calculation methods as well as the behavioural characteristics of the study animals.

Original languageEnglish
Pages (from-to)299-304
Number of pages6
JournalAquatic Biology
Volume8
Issue number3
DOIs
Publication statusPublished - 2010 Mar 16
Externally publishedYes

Keywords

  • 3D dive path
  • Data logger
  • Dead-reckoning
  • Low-pass filter
  • Sampling frequency
  • Stroke activity

ASJC Scopus subject areas

  • Oceanography
  • Ecology, Evolution, Behavior and Systematics
  • Aquatic Science
  • Ecology

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