Fish in lake ecological assessment in Europe: Quo Vadis?

It is well established that fish are sensitive indicators of environmental degradation and offer the major advantage of integrating the direct and indirect effects of stress over large scales of space and time. Nevertheless, the use of fish communities as indicators of environmental quality is highly challenging, therefore fish community has been one of the most neglected aspect of lake ecological monitoring. This paper gives an overview on fish-based assessment methods in Europe. By now, 15 Member States have finalised fish-based lake assessment systems, five of these assessment systems have been recently intercalibrated in the Alpine and Northern region, while Intercalibration is still ongoing in the Central-Baltic region. In contrary, several countries of the Mediterranean region have currently renounced the use of fish in lake assessment (mainly due to a low species richness, dominance of invasive taxa, and high costs of sampling), this opinion being strongly debated within region. This paper seeks to answer questions: How lake fish ecological assessment systems are built and used across Europe? Which pressures are assessed and are the pressure-response relationships tested? What are the main lessons and challenges of the lake fish methods` development and harmonization process

A simple fish-based approach to assess the ecological quality of freshwater reservoirs in Central Europe

The assessment of ecological quality in freshwater ecosystems is a key issue in many countries, but conditions for the development of assessment methodologies are often country-specific. This study proposes a simple methodology for the assessment of the ecological potential of reservoirs based on fish communities using a dataset covering major environmental and pressure gradients in reservoirs in the Czech Republic. Fish data obtained by gillnet sampling were correlated with a proxy of eutrophication as a key indicator of anthropogenic pressure for selecting appropriate fish-based indicators, establishing scoring criteria and developing the index of ecological quality. Expert judgement was also used to select potential fish indicators. Nine indicators were selected for the final fish-based index, fulfilling the criteria required by the Water Framework Directive. Two steps were used to validate the fish-based index quantification of its inter annual stability and sensitivity analysis of individual indicators. Finally, the index was compared to a previously developed general index for Central and Western Europe. Our study demonstrates that a combination of expert judgement and strict validation methods can result in an informative assessment of the ecological conditions, which can help identify conservation and restoration priorities. © P. Blabolil

Water Framework Directive Intercalibration: Central-Baltic Lake Fish fauna ecological assessment methods

The European Water Framework Directive (WFD) requires the national classifications of good ecological status to be harmonised through an intercalibration exercise. In this exercise, significant differences in status classification among Member States are harmonized by comparing and, if necessary, adjusting the good status boundaries of the national assessment methods. Intercalibration is performed for rivers, lakes, coastal and transitional waters, focusing on selected types of water bodies (intercalibration types), anthropogenic pressures and Biological Quality Elements. Intercalibration exercises are carried out in Geographical Intercalibration Groups - larger geographical units including Member States with similar water body types - and followed the procedure described in the WFD Common Implementation Strategy Guidance document on the intercalibration process (European Commission, 2011). The Technical report on the Water Framework Directive intercalibration describes in detail how the intercalibration exercise has been carried out for the water categories and biological quality elements. The Technical report is organized in volumes according to the water category (rivers, lakes, coastal and transitional waters), Biological Quality Element and Geographical Intercalibration group. This volume addresses the intercalibration of the Lake Central-Baltic Fish ecological assessment methods. Part A: This document comprises an overview and detailed descriptions of fish-based lake ecological assessment methods. Part B describes the construction of multiple pressure index in the Central-Baltic region. Part C describes the procedure and results of the boundary harmonisation of national fish-based lake assessment systemsJRC.D.2-Water and Marine Resource

A hitchhiker's guide to European lake ecological assessment and intercalibration

The Water Framework Directive is the first international legislation to require European countries to establish comparable ecological assessment schemes for their freshwaters. A key element in harmonising quality classification within and between Europe's river basins is an "Intercalibration" exercise, stipulated by the WFD, to ensure that the good status boundaries in all of the biological assessment methods correspond to similar levels of anthropogenic pressure. In this article, we provide a comprehensive overview of this international comparison, focusing on the assessment schemes developed for freshwater lakes. Out of 82 lake ecological assessment methods reported for the comparison, 62 were successfully intercalibrated and included in the EC Decision on intercalibration, with a high proportion of phytoplankton (18), macrophyte (17) and benthic fauna (13) assessment methods. All the lake assessment methods are reviewed in this article, including the results of intercalibration. Furthermore, the current gaps and way forward to reach consistent management objectives for European lakes are discussed. (C) 2015 The Authors. Published by Elsevier Ltd.Peer reviewe

Intercalibration of the national classifications of ecological status for Central-Baltic Lakes: Biological Quality Element: Fish fauna: Part B and C

The European Water Framework Directive (WFD) requires the national classifications of good ecological status to be harmonised through an intercalibration exercise. In this exercise, significant differences in status classification among Member States are harmonized by comparing and, if necessary, adjusting the good status boundaries of the national assessment methods. Intercalibration is performed for rivers, lakes, coastal and transitional waters, focusing on selected types of water bodies (intercalibration types), anthropogenic pressures and Biological Quality Elements. Intercalibration exercises are carried out in Geographical Intercalibration Groups - larger geographical units including Member States with similar water body types - and followed the procedure described in the WFD Common Implementation Strategy Guidance document on the intercalibration process (European Commission, 2011). The Technical report on the Water Framework Directive intercalibration describes in detail how the intercalibration exercise has been carried out for the water categories and biological quality elements. The Technical report is organized in volumes according to the water category (rivers, lakes, coastal and transitional waters), Biological Quality Element and Geographical Intercalibration group. This volume addresses the intercalibration of the Lake Central-Baltic Fish ecological assessment methods. This volume on intercalibration of the Lake Central Baltic Fish ecological assessment methods is split into three parts: Part A, a document that provides an overview and detailed descriptions of fish-based lake ecological assessment methods. Parts B and C: This document comprises two Parts, B and C. Part B describes the construction of multiple pressure index in the Central-Baltic region. Part C describes the procedure and results of the boundary harmonisation of national fish-based lake assessment systems.  JRC.D.2-Water and Marine Resource

Growth and habitat occupation of reed (Phragmites australis) in carp ponds

0\. Titelblatt und Inhaltsverzeichnis 1\. Einleitung 3 2\. Material und Methoden 8 3\. Ergebnisse 23 4\. Diskussion 60 5\. Zusammenfassung 91 6\. Summary 94 7\. Literatur 97 8\. Anhang 104Grundlage der Arbeit ist die Untersuchung von Verlandungsprozessen in den Schilfröhrichten sächsischer Karpfenteiche. Die Schwerpunkte liegen auf der zeitlichen und örtlichen Entwicklung von Schilf (Phragmites australis) bei günstigen Wachstumsvoraussetzungen. Die Untersuchungen sind in drei wesentliche Einheiten gegliedert: das Wachstum von Halmen, das Wachstum von Halmen in Beständen und die Habitatbesetzung von Schilf. Das Wachstum von Halmen ist durch den im Jahresverlauf unveränderlichen Durchmesser begrenzt. Die für einen Halm mit gegebenem Durchmesser erreichbare Länge lässt sich errechnen. Damit kann neben der erreichten Länge eines Halmes auch seine erreichbare Länge bestimmt werden. Anhand des Quotienten aus erreichter und erreichbarer Länge (relative Länge) lässt sich einschätzten, inwiefern durch den Durchmesser vorgegebene Wachstumsvoraussetzungen ausgenutzt werden. Die Biomasse einzelner Schilfhalme hängt von der Oberfläche der Halme ab (nicht von ihrem Volumen). Dadurch bleibt die flächenbezogene Biomasse (standing crop) in Schilfbeständen unabhängig von der Halmdichte. Dies widerspricht dem �-3/2 power law�, nach dessen Gesetzmäßigkeiten in dichten Reinkulturen wenige große Pflanzen eine höhere Biomasse ausbilden sollten. Schilfhalme verschiedener Herkunft lassen sich anhand ihrer Durchmesser, Längen, relativer Längen und Dichten unterscheiden. Unterschiede liegen in den Mittelwerten der Eigenschaften, in ihrer saisonalen Entwicklung und in der Entwicklung der Variationskoeffizienten. Die Schilfbestände der Karpfenteiche lassen sich in fünf charakteristische Entwicklungstypen einteilen: Invasionsschilf, stabiles Zentralschilf, Riesenschilf, Steiluferschilf und Bültenschilf. Die Entwicklungstypen entstehen in Abhängigkeit von Standortfaktoren und Alter der Bestände. Sie entsprechen Zuständen einer langfristigen Änderung. Prinzipiell entwickelt sich die Bestandsstruktur von dünnen, kurzen Halmen in hohen Dichten zu wenigen großen Halmen. Die Habitatbesetzung von Schilf ist fast ausschließlich ein Wachstumsvorgang. Im Rahmen der Untersuchungen wurde keine erfolgreiche Ausbreitung durch generative Diasporen gefunden. Eine vegetative Fortpflanzung mit der Entstehung von Ramets als selbstständig lebende Einheit trat in nur einem Fall auf. Damit wächst Schilf in Form ausgedehnter Individuen, als ein Organismus aus potenziell selbstständig lebensfähigen Teilen, die dennoch physiologisch verbunden bleiben. Die Habitatbesetzung ist ein Wachstumsvorgang aus vorhandenen Beständen und beinhaltet nahezu keine Fortpflanzung. Dabei folgt das Wachstum von Schilf einer labilen Strategie mit standortbedingten Teil-Taktiken. Unter günstigen Bedingungen wird eine Taktik verfolgt, die Merkmale des Phalanx-Wachstums aufweist, ungünstige Habitate werden durch ein Wachstum mit Guerilla-Merkmalen besetzt. Die physiologische Verbundenheit der Module ist dabei notwendig, um erfolgreiches Durchqueren ungünstiger Standorte zu gewährleisten. Bei Schilf können sich daher Teile eines Individuums in der Ausprägung von Wachstumsmerkmalen im Guerilla- Phalanx-Kontinuum unterscheiden. Damit ist morphologische Variabilität entscheidender Teil der Wachstums- und Habitatbesetzungsstrategie von Schilf und Unterschiede zwischen Beständen reflektieren unterschiedliche Entwicklungszustände. Die vorliegende Arbeit liefert eine alternative oder zumindest ergänzende Erklärung für die auf Umwelteinflüsse oder genetische Ursachen zurück geführte morphologische Variabilität von Schilf.The present paper is based on investigations of reed stands (Phragmites australis) in carp ponds in Saxony, Germany. It focuses on the aspect of space and time in the development of reed if favorable conditions for growth are given. The results are divided into three main units: the growth of culms, the growth of culms in stands and the habitat occupation of reed. The growth of culms is limited by their diameter, which remains constant throughout the vegetation period. The maximum length of a culm with a given diameter can be calculated. A relative length can be determined by dividing the actual length of a culm through the length it potentially could have reached. The relative length indicates the amount, in which the culm takes advantage of the prerequisites for growth given by its diameter. The biomass of single culms depends on their surface (not on their volume). Thus, the standing crop of reed remains independent of the culm density. This contradicts the -3/2 power law, which predicts an increase of the standing crop during self-thinning in dense monocultures. Reed stands can be distinguished by changes of distributions, means and variances of diameter, density, length and relative length of the culms during the vegetation period. Five characteristic patterns of seasonal development were found: invasive reed, stable reed of central regions, giant reed, steep-shore reed, and reed tussocks. The patterns of development represent states of a long-term change of the stand structure dependent on its age and environmental influences. Basically, the development is directed from thin culms of high density towards less and thicker culms. The habitat occupation by reed is almost exclusively a process of growth. No successful dispersal of sexual diaspores was found. Cloning was found only once and considering the amount of investigation, asexual reproduction is a rare event. Reed does hardly ever split up into ramets, which are defined as clonally originated, physically separated and living descendants of a former individual. Reed grows as an extensive individual, an organism compounded of units which are capable of living independently, but nonetheless remain connected. Therefore, the habitat occupation by reed occurs by growth of existing stands and barely includes reproduction or dispersal. The habitat occupation of reed follows an �unstable strategy of habitat-dependant partial tactics�. If growth conditions are good, the tactic is phalanx-like. Environments with less favourable conditions are occupied with a tactic showing traits of the guerrilla growth type. The physiological integration of modules guarantees the successful passage of unsuitable areas. The intra- individual combination of tactics leads to differences between parts of a single organism according to their position in a guerrilla-phalanx-gradient. The morphological variability is essential for the strategy of growth and habitat occupation of reed. Differences between stands reflect different stages of development. The results presented are an alternative or at least an additional explanation for the morphologic variability of reed, which is predominantly explained by environmental factors or genetic prerequisites