Author(s):
Matono, Paula 
; Bernardo, João Manuel ; Ferreira, Maria Teresa ; Formigo, Nuno ; Raposo Almeida, Pedro ; Ilhéu, Maria
Date: 2012
Persistent ID: http://hdl.handle.net/10174/6390
Origin: Repositório Científico da Universidade de Évora
Subject(s): Ecological quality assessment; Portugal; freshwater fish; water framework directive; river-types
Description
The use of river-types is of practical value, serving as groups for which
assessment procedures can be developed and applied. An abiotic typology
was set by the Portuguese Water Agency, mainly based on 6 major
morphoclimatic regions. However, to be biologically meaningful, this typology
should fit the distribution patterns of the biological quality elements
communities proposed in Water Framework Directive under the lowest
possible human pressure. This study aimed to identify and characterize
fish-based geographical groups for continental Portugal and their environmental
and geographical discriptors, using taxonomic and functional
traits. Sampling took place between 2004 and 2006 during Spring. Fish
fauna from 155 reference sites was analysed using a multivariate
approach. Cluster Analysis on fish composition identified 10 fish-groups,
expressing a clear correspondence to the river basin level, due to the
restrict basin distribution of many species. Groups showed a wider aggregation
in 4 regions with a larger geographical correspondence, statistically
supported by Similarity Analysis, both on fish composition and mostly on
fish metrics/guilds. Principal Components Analysis revealed major environmental
drivers associated to fish-groups and fish-regions. Fish-groups
were hierarchically grouped over major and local regions, expressing a
large-scale response to a North-South environmental gradient defined by
temperature, precipitation, mineralization and altitude, and a regional scale
response mainly to drainage area and flow discharge. From North to
South, fish-regions were related to the morphoclimatic regions. Results
contributed to reduce redundance in abiotic river-types and set the final
typology for Portuguese rivers, constituting a fundamental tool for planning
and managing water resources.
