Indicator taxa of benthic diatom communities: a case study in Mediterranean streams

Abstract

A key issue in the implementation of the Water Framework Directive is the classification of streams and rivers using biological quality parameters and type-specific reference conditions. Four groups of stream types were defined in NE Spain on the basis of 152 diatom samples by means of detrended correspondence analysis and classification techniques. Diatom analysis was restricted to epilithic taxa, and the sites included gradients ranging from near-natural streams to sites with poor ecological quality. The main gradient shows a clear separation of sites in relation to the degree of human influence: polluted streams (mainly located in the lowlands) differ from streams in mountainous areas and in the Pyrenees. A second gradient is related to physiographical features. Headwater streams can be distinguished by their catchment geology. The type-specific diatom taxa for the stream types studied were determined by using indicator species analysis (IndVal). The type-specific taxa from near-natural streams are coincident with the indicator taxa for high ecological status. Human impact reduced the typological heterogeneity of the diatom community composition. Overall, the diatom communities in NE Spain exhibit a regional distribution pattern that closely corresponds with that observed in river systems elsewhere. Physiographical differences are only evident in undisturbed sites, while nutrient enrichment and other human disturbances may mask the regional differences in the distribution of diatom communities.

Benthic diatom communities in high altitude lakes: a large scale study in the French Alps

“…Tornés et al, 2007). Indeed, pollution is often considered as homogenising species composition (Leira and Sabater, 2005;Pan et al, 1999;Tornés et al, 2007). But pollution was not the overriding parameter in our study area since high altitude lakes are upstream most of human activities.…”

“…Groups A2 and B2 were represented by only one lake therefore indicator species were not possible to calculate for these groups. (Tornés et al, 2007). Moreover, E. subminuta, which is an indicative species of this community, is usually leaving in calcareous ecosystems (Hofmann et al, 2011).…”

“…This is often the case when pollution Àa local varying factor-masks the impact of geology in rivers (e.g. Tornés et al, 2007). Indeed, pollution is often considered as homogenising species composition (Leira and Sabater, 2005;Pan et al, 1999;Tornés et al, 2007).…”

“…Pan et al, 2000;Leira and Sabater, 2005;Tornés et al, 2007). Therefore, because high-altitude lakes are profuse and known to be pristine, these ecosystems appear to be good study sites to analyze the influence of natural parameters on benthic diatoms communities.…”

Effects of vineyard coverage and extent on benthic macroinvertebrates in streams of Northern California

“…However, many studies have shown a strong relationship between streamflow reductions and benthic response in Mediterranean-climate streams (Bonada et al, 2006(Bonada et al, , 2007aTorne´s et al, 2007;Morais, 2008). Furthermore, prolonged drought in Mediterranean-climate regions has particularly strong effects on the abundance and composition of benthic-macroinvertebrate communities in small streams (Beˆche et al, 2006;Beˆche and Resh, 2007a, b).…”