Are Water Framework Directive stream types biologically relevant? The case of the Mondego river, Portugal

Abstract

-Typology schemes are useful in partitioning natural spatial variability and thus helping implementing bioassessment methods. They have become widely accepted in Europe after the publication of the Water Framework Directive (WFD). The major objective of this study was to test if six Portuguese predefined physical stream-types (using System-B of the WFD) are concordant with macroinvertebrate assemblages collected in 31 undisturbed sites in a Portuguese river basin. A top-down (stream types defined by physical attributes) and a bottom-up approach (river classes defined by biological communities) were used. No significant differences were found in the mean number of taxa and abundance of different physical stream types and few taxa are characteristic of specific stream types. Discriminant analysis (DA) considering family-level composition revealed that all stream-types were significantly different and the cross-validation process showed that all stream-types had more than 50% of their samples correctly assigned. On the other hand, the bottom-up approach based on a correspondence analysis (CA) showed some overlap of the macroinvertebrate communities of pre-defined stream types, indicating that variations in the macroinvertebrate community structure was primarily related to altitude, mineralisation and a temporal gradient. DA crossvalidation and CA results suggest that tested stream types do not account for natural temporal changes known to affect macroinvertebrate communities in this Mediterranean basin and that the WFD typology should account for these natural variations. The exclusion of natural variability could indicate impairment when it does not exist or no impairment when it does exist (type I and II statistical errors).

River classification as the basis for freshwater biological assessment in overseas Europe: Issues raised from Guadeloupe (French Lesser Antilles)

“…The WFD emphasizes the importance of geographic differences in biotic and abiotic characteristics of freshwater ecosystems , so that classification has become an integral part of efforts to study, monitor, and manage ecosystems at a regional scale . The published literature unambiguously shows that limited scientific effort has been directed at characterizing how rivers in overseas Europe differ in terms of biological community structure, and how communities respond to changes in abiotic conditions.…”

Biomonitoreo de la calidad del agua en los ríos ibéricos: lecciones aprendidas

“…En ambos casos, como lo que queremos es establecer el estado de los ríos y hay que conocer sus condiciones de referencia, la tipología debe realizarse usando parámetros que no estén alterados por la acción del hombre (Bonada et al, 2002a;Munné & Prat, 2004). Algunos trabajos han comparado las tipologías hidromorfológicas con las biológicas tanto en España (Sanchez-Montoya et al, 2007), como en Portugal (Chaves et al, 2011), y han puesto de manifiesto las diferencias entre ellas. Cabe destacar que no siempre las tipologías elaboradas a partir de datos ambientales coinciden exactamente con las agregaciones taxonómicas.…”

Invertebrate distribution patterns and river typology for the implementation of the water framework directive in Martinique, French Lesser Antilles

“…According to the WFD guidelines, ecological health must be defined in terms of similarity to an undisturbed ("reference") state. The Reference Condition Approach (RCA, Bailey et al, 2003) notably implies the characterization of biological communities (fish, invertebrates, diatoms, phytoplankton, plants) expected to occur where there is (almost) no anthropogenic disturbance (Chaves et al, 2011;Wallin et al, 2003). Geomorphological, physical, and chemical attributes of freshwater systems have to be associated with biological features too when defining undisturbed conditions.…”