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Efficient abstracting of dive profiles using a broken-stick model

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Efficient abstracting of dive profiles using a broken-stick model. / Photopoulou, T.; Lovell, Philip; Fedak, M.A.; Thomas, L.; Matthiopoulos, J.

In: Methods in Ecology and Evolution, Vol. 6, No. 3, 03.2015, p. 278-288.

Research output: Contribution to journalArticle

Harvard

Photopoulou, T, Lovell, P, Fedak, MA, Thomas, L & Matthiopoulos, J 2015, 'Efficient abstracting of dive profiles using a broken-stick model', Methods in Ecology and Evolution, vol. 6, no. 3, pp. 278-288. https://doi.org/10.1111/2041-210X.12328

APA

Photopoulou, T., Lovell, P., Fedak, M. A., Thomas, L., & Matthiopoulos, J. (2015). Efficient abstracting of dive profiles using a broken-stick model. Methods in Ecology and Evolution, 6(3), 278-288. https://doi.org/10.1111/2041-210X.12328

Vancouver

Photopoulou T, Lovell P, Fedak MA, Thomas L, Matthiopoulos J. Efficient abstracting of dive profiles using a broken-stick model. Methods in Ecology and Evolution. 2015 Mar;6(3):278-288. https://doi.org/10.1111/2041-210X.12328

Author

Photopoulou, T. ; Lovell, Philip ; Fedak, M.A. ; Thomas, L. ; Matthiopoulos, J. / Efficient abstracting of dive profiles using a broken-stick model. In: Methods in Ecology and Evolution. 2015 ; Vol. 6, No. 3. pp. 278-288.

Bibtex - Download

@article{80aaaf5e948b4a41a4f868eef02b726c,
title = "Efficient abstracting of dive profiles using a broken-stick model",
abstract = "For diving animals, animal-borne sensors are used to collect time-depth information for studying behaviour, ranging patterns and foraging ecology. Often, this information needs to be compressed for storage or transmission. Widely used devices called conductivity-temperature-depth satellite relay data loggers (CTD-SRDLs) sample time and depth at high resolution during a dive and then abstract the time-depth trajectory using a broken-stick model (BSM). This approximation method can summarize efficiently the curvilinear shape of a dive, using a piecewise linear shape with a small, fixed number of vertices, or break points. We present the process of abstracting dives using the BSM and quantify its performance, by measuring the uncertainty associated with the profiles it produces. We develop a method for obtaining a confidence zone and an index for the goodness-of-fit (dive zone index, DZI) for abstracted dive profiles. We validate our results with a case study using dives from elephant seals (Mirounga spp.). We use generalized additive models (GAMs) to determine whether the DZI can be used as a proxy for an absolute measure of fit and investigate the relationship between the DZI and the dive shape. We found a strong correlation between the residual sum of squares (RSS) for the difference between the detailed and abstracted profiles, and the DZI and maximum residual (R4), for dives resulting from CTD-SRDLs (69{\%} deviance explained). On its own, the DZI explained a lower percentage of deviance which was variable for abstracted dives with different numbers of break points. We also found evidence for systematic differences in the DZI for different dive shapes (65{\%} deviance explained). Although the proportional loss of information in the abstraction of time-depth dive profiles by BSM is high, what remains is sufficient to infer goodness-of-fit of the abstracted profile by reversing the abstraction process. Our results suggest that together the DZI and R4 can be used as a proxy for the RSS, and we present the method for obtaining these metrics for BSM-abstracted profiles.",
keywords = "Animal telemetry, Broken-stick model, CTD-SRDL, Dive profile, Dive type, Dive zone index, Elephant seal, Data abstraction",
author = "T. Photopoulou and Philip Lovell and M.A. Fedak and L. Thomas and J. Matthiopoulos",
note = "This work was supported by SMRU Ltd (now SMRU Marine) in the form of a PhD fellowship (T.P.). Completion of the manuscript was supported by a National Research Foundation Scarce Skills Postdoctoral Fellowship at the University of Cape Town, South Africa (T.P.). The CTD-SRDL data presented in this manuscript were collected as part of a project funded by the Natural Environment Research Council (NERC) grants NE/E018289/1 and NER/D/S/2002/00426.",
year = "2015",
month = "3",
doi = "10.1111/2041-210X.12328",
language = "English",
volume = "6",
pages = "278--288",
journal = "Methods in Ecology and Evolution",
issn = "2041-210X",
publisher = "John Wiley & Sons, Ltd (10.1111)",
number = "3",

}

RIS (suitable for import to EndNote) - Download

TY - JOUR

T1 - Efficient abstracting of dive profiles using a broken-stick model

AU - Photopoulou, T.

AU - Lovell, Philip

AU - Fedak, M.A.

AU - Thomas, L.

AU - Matthiopoulos, J.

N1 - This work was supported by SMRU Ltd (now SMRU Marine) in the form of a PhD fellowship (T.P.). Completion of the manuscript was supported by a National Research Foundation Scarce Skills Postdoctoral Fellowship at the University of Cape Town, South Africa (T.P.). The CTD-SRDL data presented in this manuscript were collected as part of a project funded by the Natural Environment Research Council (NERC) grants NE/E018289/1 and NER/D/S/2002/00426.

PY - 2015/3

Y1 - 2015/3

N2 - For diving animals, animal-borne sensors are used to collect time-depth information for studying behaviour, ranging patterns and foraging ecology. Often, this information needs to be compressed for storage or transmission. Widely used devices called conductivity-temperature-depth satellite relay data loggers (CTD-SRDLs) sample time and depth at high resolution during a dive and then abstract the time-depth trajectory using a broken-stick model (BSM). This approximation method can summarize efficiently the curvilinear shape of a dive, using a piecewise linear shape with a small, fixed number of vertices, or break points. We present the process of abstracting dives using the BSM and quantify its performance, by measuring the uncertainty associated with the profiles it produces. We develop a method for obtaining a confidence zone and an index for the goodness-of-fit (dive zone index, DZI) for abstracted dive profiles. We validate our results with a case study using dives from elephant seals (Mirounga spp.). We use generalized additive models (GAMs) to determine whether the DZI can be used as a proxy for an absolute measure of fit and investigate the relationship between the DZI and the dive shape. We found a strong correlation between the residual sum of squares (RSS) for the difference between the detailed and abstracted profiles, and the DZI and maximum residual (R4), for dives resulting from CTD-SRDLs (69% deviance explained). On its own, the DZI explained a lower percentage of deviance which was variable for abstracted dives with different numbers of break points. We also found evidence for systematic differences in the DZI for different dive shapes (65% deviance explained). Although the proportional loss of information in the abstraction of time-depth dive profiles by BSM is high, what remains is sufficient to infer goodness-of-fit of the abstracted profile by reversing the abstraction process. Our results suggest that together the DZI and R4 can be used as a proxy for the RSS, and we present the method for obtaining these metrics for BSM-abstracted profiles.

AB - For diving animals, animal-borne sensors are used to collect time-depth information for studying behaviour, ranging patterns and foraging ecology. Often, this information needs to be compressed for storage or transmission. Widely used devices called conductivity-temperature-depth satellite relay data loggers (CTD-SRDLs) sample time and depth at high resolution during a dive and then abstract the time-depth trajectory using a broken-stick model (BSM). This approximation method can summarize efficiently the curvilinear shape of a dive, using a piecewise linear shape with a small, fixed number of vertices, or break points. We present the process of abstracting dives using the BSM and quantify its performance, by measuring the uncertainty associated with the profiles it produces. We develop a method for obtaining a confidence zone and an index for the goodness-of-fit (dive zone index, DZI) for abstracted dive profiles. We validate our results with a case study using dives from elephant seals (Mirounga spp.). We use generalized additive models (GAMs) to determine whether the DZI can be used as a proxy for an absolute measure of fit and investigate the relationship between the DZI and the dive shape. We found a strong correlation between the residual sum of squares (RSS) for the difference between the detailed and abstracted profiles, and the DZI and maximum residual (R4), for dives resulting from CTD-SRDLs (69% deviance explained). On its own, the DZI explained a lower percentage of deviance which was variable for abstracted dives with different numbers of break points. We also found evidence for systematic differences in the DZI for different dive shapes (65% deviance explained). Although the proportional loss of information in the abstraction of time-depth dive profiles by BSM is high, what remains is sufficient to infer goodness-of-fit of the abstracted profile by reversing the abstraction process. Our results suggest that together the DZI and R4 can be used as a proxy for the RSS, and we present the method for obtaining these metrics for BSM-abstracted profiles.

KW - Animal telemetry

KW - Broken-stick model

KW - CTD-SRDL

KW - Dive profile

KW - Dive type

KW - Dive zone index

KW - Elephant seal

KW - Data abstraction

UR - http://onlinelibrary.wiley.com/doi/10.1111/2041-210X.12328/suppinfo

UR - http://www.smru.st-and.ac.uk/Instrumentation/Overview/

U2 - 10.1111/2041-210X.12328

DO - 10.1111/2041-210X.12328

M3 - Article

VL - 6

SP - 278

EP - 288

JO - Methods in Ecology and Evolution

JF - Methods in Ecology and Evolution

SN - 2041-210X

IS - 3

ER -

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