Dear Marmam subscribers,
the following article has been pubished on Remote Sensing of the
Environment, and it is now available online at:
http://dx.doi.org/10.1016/j.rse.2007.11.017
Please note access to the full text of this article will depend on
your personal or institutional entitlements.
Best regards,
Simone Panigada
Modelling habitat preferences for fin whales and striped dolphins in
the Pelagos
Sanctuary (Western Mediterranean Sea) with physiographic and remote
sensing variables
Simone Panigada, Margherita Zanardelli, Monique MacKenzie, Carl
Donovan,
Frédéric Mélin, Philip S. Hammond
A B S T R A C T
One of the needs of the Pelagos Sanctuary for the Conservation of
Mediterranean Marine Mammals is
information on critical habitats for cetaceans. This study modelled
habitat use and preferences of fin whales
and striped dolphins (the two most abundant species in the area) with the
aim of providing this information,
using sighting data collected between 1993 and 1999. The study area was
divided into a 2 latitude by 2
longitude grid. The explanatory variables considered in the models were
physiographic variables (mean, range
and standard deviation of depth and slope, and distance from the nearest
coastline) and remotely-sensed data
(Sea Surface Temperature and Chlorophyll-a concentration). The former
were calculated for each cell using GIS
tools, while the latter were obtained from AVHRR and SeaWiFS sensors.
Generalized Additive Models (GAMs)
with multidimensional smoothers were used to model the distribution of
fin whales and striped dolphins in
relation to these variables, and Classification And Regression Trees were
used for habitat characterization and
predictive models. The GAMs were coupled with Generalized Estimating
Equations (GEEs) to account for
temporal autocorrelation in the errors and to help ensure model selection
was reliable; the QIC statistic was
used alongside GEE-based p-values. Bathymetric features were the most
valuable predictors in the Pelagos
Sanctuary area for both species. Sea Surface Temperature values were
indicators of striped dolphin and fin
whale presence, with both species showing a tendency to prefer colder
waters (2124 °C). Chl-a levels were
selected by the GAM models only for striped dolphins, and with large
associated uncertainty; this may be
related to the relatively brief period examined (only 2 years) and/or to
any functional relationship operating at a
different geographical or temporal scale. The boosted classification
trees however indicated an importance of
Chl-a for both species. The techniques applied to this dataset proved to
be valuable tools to describe habitat use
and preferences of cetaceans, and the use of the remotely-sensed data can
substantially improve the
predictions. The results of this study will be used for assessing
critical habitats within the Pelagos Sanctuary
and will provide information for conservation and management in the
Sanctuary.
Keywords: Mediterranean Sea, Conservation/management, Critical habitat,
Habitat modelling, MPA, Fin whale, Striped dolphin
___________________________
Simone Panigada, Ph.D.
Vice-President
panigada@inwind.it
Tethys Research Institute
Viale G.B. Gadio 2, 20121 Milano, Italy
tel. +39 0272001947 / 0272013943
fax +39 0286995011
tethys@tethys.org
<
http://www.tethys.org/>