View metadata, citation and similar papers at core.ac.uk brought to you by CORE provided by Duisburg-Essen Publications Online Mid-sized Mountain Streams – Typology, Assessment and Reliability of Sampling and Assessment Methods Inaugural-Dissertation zur Erlangung des Doktorgrades Dr. rer. nat. des Fachbereichs Bio- und Geowissenschaften, Landschaftsarchitektur an der Universität Duisburg-Essen vorgelegt von Armin Lorenz geboren in Leiden/NL Abgabe Juli, 2004 Mündliche Prüfung 20.10.2004 Gutachter: PD Dr. Daniel Hering, Prof. Dr. Helmut Schuhmacher Die der vorliegenden Arbeit zugrundeliegenden Experimente wurden am Institut für Ökologie in der Abteilung Hydrobiologie der Universität Duisburg-Essen durchgeführt. 1. Gutachter: PD Dr. Daniel Hering 2. Gutachter: Prof. Dr. Helmut Schuhmacher Vorsitzender des Prüfungsausschusses: Prof. Dr. Hans Hagenmaier Tag der mündlichen Prüfung: 20.10.2004 The current that with gentle murmur glides, Thou know´st, being stopped, impatiently does rage. But when his fair course is not hindered He makes sweet music with th´enamelled stones, Giving a gentle kiss to every sedge He overtaketh in his pilgrimage. And so by many winding nooks he strays With willing sport to the wild ocean. [Julia in Act 2 in “The two Gentlemen of Verona” (Shakespeare 1598 in Wells & Taylor 1988)] Dedicated to my parents and the working group of Hydrobiology at the University of Duisburg-Essen. Table of Contents Table of Contents Preface…………………………………………………………………………………………………………….1 Definitions – Abbreviations...................................................................................4 1 Validation of the German stream typology using benthic invertebrates.............8 Abstract................................................................................................................... 8 1.1 Typology of streams in Germany sampled with various protocols ......................... 9 1.1.1 Introduction .............................................................................................. 9 1.1.2 Materials and methods..............................................................................10 1.1.3 Results.....................................................................................................14 1.1.4 Discussion................................................................................................17 1.1.5 Conclusion ...............................................................................................19 1.2 Comparison of NMS resolution for taxonomic levels and quantitative differences between two stream types ...............................................................................20 1.2.1 Introduction .............................................................................................20 1.2.2 Materials and methods..............................................................................21 1.2.3 Results.....................................................................................................25 1.2.4 Discussion................................................................................................29 1.3 Typology of streams in Germany sampled with a consistent method ...................31 1.3.1 Introduction .............................................................................................31 1.3.2 Materials and methods..............................................................................32 1.3.3 Results.....................................................................................................36 1.3.4 Discussion................................................................................................41 1.4 Differences and similarities of mid-sized and large mountain streams..................46 1.4.1 Introduction .............................................................................................46 1.4.2 Characterisation of mid-sized and large mountain streams in Germany ........47 1.4.3 Materials and methods..............................................................................47 1.4.4 Results.....................................................................................................48 1.4.5 Discussion................................................................................................52 Table of Contents 2 Development of an assessment system for mid-sized streams in lower mountainous areas of Germany .................................................................. 54 Abstract..................................................................................................................54 2.1 A new method for assessing the impact of hydromorphological degradation on the macroinvertebrate fauna..................................................................................55 2.1.1 Introduction .............................................................................................55 2.1.2 Materials and methods..............................................................................57 2.1.3 Results.....................................................................................................65 2.1.4 Discussion................................................................................................71 3 Statistical tests for applying a minimum number of individuals for AQEM-method samples…. ................................................................................................ 74 Abstract..................................................................................................................74 3.1 “Electronic subsampling” of invertebrate samples: how many individuals are needed for a valid assessment result?...............................................................75 3.1.1 Introduction .............................................................................................75 3.1.2 Materials and methods..............................................................................76 3.1.3 Results.....................................................................................................79 3.1.4 Discussion................................................................................................88 Summary and Conclusions ................................................................................. 93 Deutsche Kurzfassung der Dissertation ............................................................... 96 References……………………………………………………………………………………………………106 Acknowledgements ......................................................................................... 117 Appendices……………………………………………………………………………………………………118 Preface Preface Research in ecology is like an unending staircase, which widens up the more steps you take. The closer one approaches a solution for one scientific problem, the more unanswered ones turn up elsewhere. Streams of the mountainous areas of Germany and their inhabiting aquatic invertebrate fauna were the starting point of this thesis leading to several wider perspectives. Investigating these mountain streams reveals questions about their faunal characteristics compared to lowland rivers and to high alpine rivers and even about the variability between mountain streams. At the same time, statistical theory requires us to consider the reliability and repeatability of any research result. The subsequent thesis consists of three chapters. Each chapter has its own self-contained introduction and sub-chapters on methods, results and discussion. Overall conclusions and a summary are given to integrate these pieces of research jigsaw. In the first chapter, I will try to answer questions about differences in the aquatic biota between German lowland, mountain and alpine streams, but concentrating on the mountainous and alpine regions. There have been many publications on this topic (e.g. Huet 1946; Illies 1961; Braukmann 1987; Sommerhäuser 1998; LUA 1999b; Sommerhäuser & Schuhmacher 2003) but a comprehensive statistical evaluation based on the benthic invertebrate community has not yet been conducted. Filling this gap I started from two sides with two different data sets: (1) taxa lists from all parts of Germany applying a variety of sampling protocols; (2) a smaller number of taxa lists from certain regions of Germany applying a consistent sampling protocol. The taxonomic resolution of the first and larger data set is low (mainly genus level) compared to the second data set (species level). Within the first data set the taxa lists were reduced to just presence/absence level and only a subset of taxonomic groups was considered. In the second data set abundance data and the complete benthic invertebrate community were used instead. Linking abiotic parameters to the benthic invertebrate taxa lists helped to determine the major factors, which influence macroinvertebrates to inhabit a stream reach. The question, which taxonomic resolution and data type is necessary to create stream typologies, is answered in a second step. A homogeneous data set in terms of sampling, sorting and identification was evaluated to identify the effects of different resolutions. Species level is compared to family level, using the complete taxa list is compared to using the taxonomic groups Ephemeroptera, Plecoptera, Trichoptera, Coleoptera, Odonata and 1 Preface Mollusca (EPTCOM) and using logarithmically transformed abundances is compared to results based on presence/absence data. The data sets of mid-sized and large mountain streams stimulated further research about differences in the occurrences and abundances