[MARMAM] New publication on spatial variation in maximum dive depth in grey seals in relation to foraging

Theoni Photopoulou theoni.photopoulou at gmail.com
Mon Jan 6 01:15:59 PST 2014

We are pleased to announce the publication of our paper in the
forthcoming issue of Marine Mammal Science.

Photopoulou T, Fedak MA, Thomas L and Matthiopoulos J. Spatial
variation in maximum dive depth in gray seals in relation to foraging.
doi 10.1111/mms.12092


Habitat preference maps are a way of representing animals’ space use
in two dimensions. For marine animals, the third dimension is an
important aspect of spatial ecology. We used dive data from seven gray
seals Halichoerus grypus (a primarily benthic forager) collected with
GPS phone tags (Sea Mammal Research Unit) to investigate the
distribution of the maximum depth visited in each dive. We modelled
maximum dive depth as a function of spatiotemporal covariates using a
generalized additive mixed model (GAMM) with individual as a random
effect. Bathymetry, horizontal displacement, latitude and longitude,
Julian day, sediment type, and light conditions accounted for 37% of
the variability in the data. Persistent patterns of autocorrelation in
the raw data suggest that individual intrinsic rhythm might be an
important factor, not captured by external covariates. The strength of
using this statistical method to generate spatial predictions of the
distribution of maximum dive depth is its applicability to other
plunge and pursuit divers. Despite being predictions of a point
estimate, these maps provide some insight into the third dimension of
habitat use in marine animals. The capacity to predict this aspect of
vertical habitat use may help avoid conflict between animal habitat
and coastal or offshore developments.

If you would like a reprint, please email theoni.photopoulou at uct.ac.za
or paste the doi into your browser to download the article.

Kind regards,

Theoni Photopoulou, Postdoctoral Fellow
Department of Statistical Sciences, University of Cape Town
Rondebosch 7701, Cape Town, South Africa
skype. theoni_p / email. theoni.photopoulou at u <theoni.photopoulou at gmail.com>

" Be silly. Be honest. Be kind " Ralph Waldo Emerson
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