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
[EMAIL PROTECTED]
Tethys Research Institute
Viale G.B. Gadio 2, 20121 Milano, Italy
tel. +39 0272001947 / 0272013943
fax +39 0286995011
[EMAIL PROTECTED]
<http://www.tethys.org/>
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