Petr Pařil

Assessment of Organic Pollution Effect Considering Differences between Lotic and Lentic Stream Habitats

Based on the requirements of the Water Framework Directive, a macroinvertebrate-based assessment system to evaluate the ecological quality of streams has been developed by AQEM project consortium. In the Czech Republic the impact of organic pollution was principal pressure studied, but some morphological degradation of some sampling sites could not be avoided. A multimetric assessment system for three stream types was developed. Detrended Correspondence Analysis was used for the detection of the response of macroinvertebrate communities to the gradient of organic degradation. Significant relationships between abiotic (BOD, TOC, nutrients) and biotic (saprobic index, ASPT) indicators of organic enrichment/eutrophication were identified. Separate storage of the riffle and pool components of each multi-habitat sample allowed differences between these habitats to be com- pared in context of the metrics applied in the assessment system. Lotic and lentic habitats differed in taxonomic composition, ecological traits and biotic indices. The separate assessment of the riffle and pool parts of samples provides additional useful information when combined effects of organic pollution and morphological degradation are to be considered.

Epigean gammarids survived millions of years of severe climatic fluctuations in high latitude refugia throughout the Western Carpathians

Isolated glacial refugia have been documented in Central Europe for a number of taxa, but conclusive evidence for epigean aquatic species has remained elusive. Using molecular data (mitochondrial and nuclear markers), we compared the spatial patterns of lineage diversity of the widely distributed Gammarus fossarum species complex between two adjacent biogeographically and geomorphologically distinct Central European regions: the Bohemian Massif and the Western Carpathians. We investigated if the observed patterns of spatial diversity are more likely to stem from historical or present-day factors. Phylogenetic and phylogeographic analyses revealed eight phylogenetically diverse lineages: two exhibiting local signatures of recent demographic expansion inhabit both regions, while the other six display a relict distributional pattern and are found only in the Western Carpathians. Molecular dating indicates that these lineages are old and probably diverged throughout the Miocene (7-18Ma). Furthermore, their distribution does not seem to be constrained by the present boundaries of river catchments or topography. The contrasting spatial patterns of diversity observed between the two regions thus more likely result from historical rather than contemporaneous or recent factors. Our results indicate that despite the high latitude and proximity to the Pleistocene ice sheets, the Western Carpathians functioned as long-term glacial refugia for permanent freshwater fauna, allowing the uninterrupted survival of ancient lineages through millions of years of drastic climatic fluctuations.

Ecology of Leuctra geniculata (Plecoptera: Leuctridae), an atlantomediterranean species on the north-eastern border of its area

The first records of Leuctra geniculata Stephens, 1836 in the north-eastern border of its area (the Czech Republic) are presented and an overview of references, synonyms and distribution of the species is given. The ecological preferences of the species, supported by chemical and hydromorphological parameters, are defined. Probable dissemination paths into the Czech Republic and the supposed life cycle of the species are discussed. Photographs of morphological characters, SEM photos of eggs, associated macroinvertebrate assemblages (EPT taxa) and maps of distribution are included.

Comparison of mayfly (Ephemeroptera) taxocenes of permanent and intermittent Central European small streams via species traits

The recurrent drying out of small streams in past decades has shown an urgent need to pay attention to the impact of global climate change. The objectives of this study were to describe the effect of drying out on the composition of the mayfly taxocene and evaluate the relevance of individual species traits for survival of mayflies to drying out. The mayfly taxocenes of two model localities, one at an intermittent and one at a permanent brook, were investigated in 2002, 2003 and 2005. Compared with the permanent stream, the taxocene of the intermittent stream was short of nine species, foremost rheobionts and high oxygen demand species. To explain further differences between both stream types in survival and recolonisation ability, 15 species traits were evaluated. These included so-called “ecological traits” (e.g., habitat and substrate range, density, distribution, current velocity adaptation) and “biological traits” connected with life cycle and larval/adult adaptations. Species showing the highest number of advantageous traits (with only exception of Electrogena sp. cf. ujhelyii — species of taxonomically unclear status) were able to successfully survive under the unfavourable conditions of the intermittent brook. Biological traits considered more important in many respects seem to be good predictors for assessing sensitivity to extreme temperature changes, hydrological regime fluctuations and the survival/recolonisation ability of species in exposed habitats.

ABIOTIC STREAM TYPES AND SPECIES ASSEMBLAGES: IS THERE ANY SIMPLE LINKAGE? CZECH STREAMS AND BENTHIC MACROINVERTEBRATES AS AN EXAMPLE

Ecological status assessment of water bodies according to the European Water Framework Directive (WFD) is generally based on the comparison of a reference and observed status. There are two basic approaches to define the reference conditions for a particular water body: a site-specific and a type-specific. For the latter, required by the Directive, it is necessary to create a typology of water bodies. The Directive offers two ways (system A, system B) of their inherence based on abiotic descriptors. Within the assessment based on biological elements, various metrics derived from the species assemblage composition are used. The type-specific approach is associated with a multimetric system, i.e. sets of metrics for selected stressors and specific water body types (AQEM consortium 2002). The site-specific approach, which is independent on typology and deals with abiotic conditions (descriptors) of a particular site or stretch, is associated with predictive models like the British RIVPACS (WRIGHT et al. 1993) or analogous the Czech PERLA (KOKES et al. 2001). More or less detailed knowledge of biotic and abiotic conditions of pristine or near natural sites is necessary for both approaches. Due to the fact that the metrics are generally derived from taxonomic composition of the species assemblages, a correspondence between types and these assemblages is essential for the truthfulness of the type-specific approach. Therefore, the selection of abiotic descriptors should be done very carefully. The correspondence among species assemblages of reference sites and abiotic types was tested on Czech streams and benthic macroinvertebrates.

Author Correction: A global analysis of terrestrial plant litter dynamics in non-perennial waterways

In the version of this Article originally published, the affiliation for M. I. Arce was incorrect; it should have been: 5Leibniz Institute of Freshwater Ecology and Inland Fisheries (IGB), Berlin, Germany. This has now been corrected in the online versions of the Article.