Conference Proceedings - IAD

Topic 1: Ecological processes in riverine conditions
Trophic structure of the ichthyofauna of the ripal zone
of the Danube River and three adjacent wetlands in
Bulgaria
PAVLOVA MILENA, PEHLIVANOV LUCHEZAR
Institute of Biodiversity and Ecosystem Research, Bulgarian Academy of Sciences, Sofia
1113, 2 Major Yurii Gagarin str., Phone: +3592 871 17 95/ 319; Fax: +3592 870 54 98,
lzp@abv.bg
Keywords: Food webs, Qualitative modeling, Fishcenoses
Introduction
The knowledge of the trophic structure of zoocenoses is essential to understand
how it influences the properties of the ecosystem, as a whole (Pimmet al. 1991;
Warren 1994). The scientists used two main approaches to describe the fish
trophic structure in the Lower Danube: reference data and gut content analysis.
Florea & Gheorghe (2008) used a reference data for assessing the changes of
the trophic structure of fish communities in the Romanian part of the Danube for
a 55 years period.The authors payed attention mainly on the published data for
the main trophic components in the diet and the feeding habits of the fish
species.There are several studies on the fish trophic structure in wetlands
alongside the Bulgarian Danube section such as Pehlivanov 2000, Pehlivanov et
al. 2005, Pehlivanov & Pavlova 2008. Pavlova & Pehlivanov (2012) used the
basic trophic attributes of ichthyocenoses in three Danube wetlands for modeling
the trophic webs. Trophic attributes of the fish as terminal units in the trophic
webs might be very usefull for revealing interrelationship among biocenoses in
the ecosystems helping the uncover of some specific features. Thus the main
goal of this study was to assess the trophic structure of the ichthyocenoses
within the selected wetlands and the Danube River ripal along the Bulgarian
Danube stretch, as integral part of a unified system of the riverplane.
Materials and methods:
The research was carried out within 2010 and 2011 in three wetlands adjacent to
the Danube (Srebarna Lake, Malak Preslavets Marsh and Orsoya Marshland)
and in September 2010 at some ripal sites along the Bulgarian Danube stretch
(Table 1).
In the standing water bodies fish were sampled using gill nets, fish traps and
hand net while in the Danube ripal area a seine net was used. After the species
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