Influence of the surface roughness of hard substrates on the attachment of selected running water macrozoobenthos Dissertation zur Erlangung des Doktorgrades (Dr. rer. nat.) der Mathematisch-Naturwissenschaftlichen Fakultät der Rheinischen Friedrich-Wilhelms-Universität vorgelegt von Petra Ditsche-Kuru aus Mönchengladbach Bonn, 2009 Angefertigt mit Genehmigung der Mathematisch-Naturwissenschaftlichen Fakultät der Rheinischen Friedrich-Wilhelms-Universität Bonn 1. Referent: Prof. Dr. rer. nat. habil. Wilhelm Barthlott 2. Referent: PD Dr. rer. nat. habil. Jochen Koop Tag der Promotion Contents Preface and acknowledgements 1 1. General introduction 3 2. Background and state of knowledge 5 2.1 Current in running waters 5 2.2 The influence of current on aquatic macroinvertebrates 8 2.3 Attachment devices of torrential macroinvertebrates 14 2.4 Surface texture of hard substrates and its influence on the attachment of macrozoobenthos 20 3. The surface roughness of natural hard substrates in running waters and its influence on the distribution of selected macrozoobenthos organisms 24 3.1 Introduction 26 3.2 Study area 28 3.3 Material and methods 30 3.4 Results 33 3.5 Discussion 46 3.6 Conclusions and outlook 51 4. New insights into a life in current: Do the gill lamellae of Epeorus assimilis and Iron alpicola larvae (Heptageniidae) fuction as a sucker or as friction pads? 54 4.1 Introduction 55 4.2 Material and methods 56 4.3 Results 58 4.4 Discussion 62 5. Underwater attachment in current: The role of gill lamella surfaces of the mayfly larvae Epeorus assimilis in attachment to substrates of different roughness 67 5.1 Introduction 68 5.2 Material and methods 70 5.3 Results 73 5.4 Discussion 80 6. Which surface roughness does the claw need to cling to the substrate? – Investigations on the running water mayfly larvae Epeorus assimilis (Heptageniidae, Ephemeroptera) 85 6.1 Introduction 86 6.2 Material and methods 88 6.3 Results 91 6.4 Discussion 99 7. General Discussion 105 8. Summary 113 9. Zusammenfassung 115 References 117 Appendix 132 Curriculum vitae 164 List of abbreviations ANOVA analyse of variances d.f. degree of freedom Chi-Sq Chi-Square λc wavelength µ friction coefficient Δ µ difference of friction coefficients in larvae with and without gill lamellae F friction force Δ F difference of friction force in larvae with and without gill lamellae HMDS 1,1,1,3,3,3-Hexamethyldisilasan p-profile unfiltered profile P Probability value r-profile filtered profile Ra arithmetic roughness average RaH0 Ra measured in coarse roughness setting RaH2 Ra measured in fine roughness setting Re Reynolds number Rk core roughness depth RK core roughness ratio Rpk reduced peak height RPk peak-valley proportion Rvk reduced valley depth Rz average maximum height of the profile S substrate S1-S4 substrate types SEM scanning electron microscopy S.D. standard deviation ST 1-4 seta types V flow velocity W1-W3 three ranges of normal forces applied in experiments Preface and acknowledgements Everybody who ever tried to swim against the flow or simply puts his hand in flowing water gets an impression of the forces acting on animals in running waters. To cope with these flow forces animals developed a fascinating diversity of adaptations like attachment devices supporting bottom dewlling animals to maintain their position in the current. So far little is known about the interplaybetween the microtexture of solid substrates and these attachment devices. Are there surface textures animals cannot hold on? Are there other textures advantageous to cling to? Dealing with these questions I was able to find first interesting answers. Also I realized that we just start to understand this interplay and much more work can (and should) be devoted to this topic in future. This thesis was carried out at the Nees Institute for Biodiversity of Plants (University of Bonn) in close collaboration with the german Federal Institute of Hydrology (Koblenz). This work was accomplished under the project “Investigation of the relation between surface texture and macrozoobenthos attachment devices against the background of the development of optimized surfaces for hydraulic engineering” which was financially supported by the Federal Ministry of Transport, Building and Urban Affairs. Many people contributed for this study. First of all, I wish to thank PD Dr. Jochen Koop (Federal Institute of Hydrology, Koblenz), who had the initial idea to investigate the interplay between surface roughness and attachment in macrozoobenthos in running waters. He directed my interest to this fascinating topic, supervised this study and made it possible for me to use their comprehensive technical equipment of the Federal Institute of Hydrology. Moreover, I am indebted to Prof. Dr. Wilhelm Barthlott (Nees Institute for Biodiversity of Plants, Bonn) for supervision of this thesis, his generous support and helpful discussions. He enabled me to take a deeper look on aquatic attachment devices by the fascinating technique of scanning electron microscopy. I would also like to express my special thank to Prof. Dr. Stanislav Gorb (Max Plank Institute for Metal Research, Stuttgart; University of Kiel) for inspiring discussions and helpful comments regarding Chapters 4 and 5 and the invitation to Stuttgart for research purposes. This stay allowed me to explore new techniques and gain more understanding about the functioning of attachment devices in general. I thank Conny Miksch (Max Plank Institute for Metal Research, Stuttgart) for her steady technical support during this time. The equal opportunity commissioner of the Max Plank Institute for Metal Research is greatly thanked 2 Preface and acknowledgements for arranging a child-care place in Stuttgart for my little daughter that made it possible for me to work their. Moreover, I am indebted to the University of Bonn for financial support of this research opportunity out of the Maria von Linden-programme. Special thank for assistance goes to the whole department of animal ecology of the Federal Institute of Hydrology. Bernd Mockenhaupt provided excellent technical assistance and was a great help during the field work. Bettina Salinus helped with profilometric measurements. Many thanks to Barbara Anderer for supporting the determination of macrozoobenthos animals. Moreover, Dr. Christian Ortmann, Bettina Salinus, Kathrin Busch, and Stefan Wieland supported some of the field work. Moreover, I wish to thank the staff of the Nees Institut for the support given in many ways. Dr. Holger Bohn gave helpful comments on Chapter 4. Georg Fisher and Zdravko Colic assisted some of the field trips and helped preparing animals for the SEM. I am very grateful to Ronald Bellstedt (Museum of Natural History of the city of Gotha) for making available specimens of E. assimilis larvae. The Senckenberg Research Institute and Natural History Museum kindly provided I. alpicola larvae which are under protection in Germany. More specimens of I. alpicola larvae have been collected by Laurent Vuataz (Musee cantonal de zoologie, Lausanne) in the Swiss Alps to whom I express my gratitude. Many thanks to Dr. Janice Peters (University of Florida) for kindly providing examples of Drunella doddsi. I thank Mr. Bernd Uebelmann (Federal Institute of Hydrology) for proof-reading parts of this thesis. My sincere thanks to Dr. Andreas Frutiger (former EAWAG Dübendorf) and Dr. Carola Winkelmann (TU Dresden) for helpful comments to chapter 4. Other helpful comments have been provided by Prof. Dr. Adam Summers (San Diego State University) to the topic of chapter 5, by Dr. Georg Becker (University of Cologne) to chapter 6 and by Dr. Tanja Bergfeld (Federal Institute of Hydrology) to Chapter 3. Last but not least, I wish to express my warmest gratitude to my family who supported me in so many ways. My mother Ursula and Barbaros took care of my little daughter Celine so often and they even accompanied us to several conferences and research stays. I thank my daughter Celine for her patience with me when I had to work so often. I also thank her for sometimes forcing me to make a break and see the world with her children’s eyes reminding me of the diversity of live in all its ways. Chapter 1 General introduction Current is the dominating factor of selection for organisms in running waters (Einsele 1960). Beside benefiting from positive effects that water flow has for respiration, nutrient and food supplies aquatic animals have to cope with the flowing water which can develop an immense force of pushing on them (Allan 1995). During evolution, animals living in running water have developed a great variety of behavioural and morphological adaptations to current (Statzner 1987 according to different authors). To the latter belong specialized body shape and small body size, which have minimising influence on the flow forces acting on the animals (Nachtigall 1982, Vogel 1996). Further, the bottom-dwelling macrozoobenthos developed more or less specialized devices in order to attach themselves to the substrate to withstand the forces of flow. For the torrential fauna which inhabits the current-exposed surfaces of stones in running waters, the following attachment devices are described: suckers, claws, hooks, secretions, glues, friction pads, and increased marginal contact (e.g.: Steinmann 1907, Dodds and Hisaw 1924, Hora 1930, Ruttner 1962, Hynes 1970, Nachtigall 1974, Smith and Dartnall 1980, Kiel et al. 1989, Wichard et al. 1995, Frutiger 2002). Some of these attachment devices are assumed to function only on substrates with a suitable surface roughness. For example, sucker devices require smooth substrates while hooks or claws require irregular surfaces (Hora 1936, Hynes 1970, Nachtigall 1974). Furthermore, from terrestrial animals like flies, beetles, and geckos it is known that the roughness of the substrate plays an important role for the maximal attachment force developed by setose attachment pads (e.g. Gorb 2001, Huber et al. 2007) and claws (Dai et al. 2002). Some values of surface roughness are associated with strongly decreased attachment ability in these terrestrial attachment systems (MPI 2001).