Effect of abiotic and biotic factors on the abundance of
waterbird in Grado-Marano Lagoon (Italy)
Alfredo Altobelli *, Tatsiana Hubina, Stefano Sponza, Alberto Sisto
Life Science Department, University of Trieste, Via Weiss, 2
34127 – Trieste, Italy
ABSTRACT
The purpose of this paper is to assess the influence of several biotic and abiotic factors on the abundance of waterbirds in
the Grado-Marano Lagoon.
The Grado-Marano Lagoon is situated in the Northeast of the Adriatic Sea with an extension of approximately 160 km2.
ASTER satellite images were utilized to classify different types of morphologies and habitat, including sea grass
meadows. Four abiotic factors (total nitrogen, total phosphorous, alkalinity and sediment texture) and three biotic factors
(benthic community, sea grass meadows and waterbird guild abundance) were integrated into a GIS.
A regular UTM grid of square cells (Operational Geographic Units, OGUs), 1km x 1km, was superimposed on the entire
lagoon.
Using the Hierarchical Cluster Analysis (HCA) technique it was possible to delineate ecological units (clusters of OGUs)
and Principal Component Analysis (PCA) was used to reduce the dimensionality of the factors considered. Subsequently,
Correspondence Analysis (CA) was used to examine the relationship between waterbird guild abundance and ecological
units.
Keywords: Grado Marano lagoon, GIS, Remote Sensing, Multivariate Analysis, sea grass meadows, waterbird guild
1. INTRODUCTION
Geographic Information Systems (GIS) represent a considerable change in environmental data management, as they
connect territorial information to different databases, allowing for the “integration” of the territory, adding and producing
new information. The use of remote sensing tools, either aerial or based on satellite, multi- and hyper-spectral, permits
the gathering of all kinds of territorial information, and the investigation of territorial aspects that are very difficult to
monitor [1], [2]. The effectiveness of GIS was optimized by combination of GIS and statistical analysis and in particular
by the application of multivariate methods. In this case GIS is not an isolated technology but part of an integrated
methodology of analysis. Multivariate analysis renders legible and decipherable a considerable amount of data sets
which are difficult to understand at a glance.
2. STUDY AREA
The Grado and Marano lagoon system is located in Northern Adriatic in the Friuli Venezia Giulia Region (Fig. 1), at the
eastern end there is the Isonzo river, at the western the Tagliamento river, to the south there is a littoral belt formed by
islets of variable stability, and to the north there is the coast line, developed irregularly for 60 km. The area extension is
of 16.000 ha, the length is nearly 32 km and the width 5 km. Marano is the western part of the lagoonal system and
Grado is in the East. Two zones included in the lagoon are protected by the Ramsar convention on wetlands of
international interest, also, according to the “Birds” directive (79/409/CE) and the “Habitat” directive (92/53/EC) the
whole lagoon is included in ∗Natura 2000 network (SAC – IT3320037). The Grado and Marano lagoon system, including
the Isonzo river mouth area, is one of the richest avifauna areas in Europe. Over 300 species have been recorded in this
∗
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Remote Sensing for Agriculture, Ecosystems, and Hydrology X, edited by Christopher M. U. Neale, Manfred Owe,
Guido D'Urso, Proc. of SPIE Vol. 7104, 710404 · © 2008 SPIE · CCC code: 0277-786X/08/$18 · doi: 10.1117/12.800292
Proc. of SPIE Vol. 7104 710404-1