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PDF hosted at the Radboud Repository of the Radboud University Nijmegen The following full text is a publisher's version. For additional information about this publication click this link. http://hdl.handle.net/2066/148230 Please be advised that this information was generated on 2021-10-04 and may be subject to change. COMPONENT STUDIES IN SEAGRASS ECOSYSTEMS ALONG WEST EUROPEAN COASTS COMPONENT STUDIES IN SEAGRASS ECOSYSTEMS ALONG WEST EUROPEAN COASTS Promotor: Prof. Dr. С. den Hartog COMPONENT STUDIES IN SEAGRASS ECOSYSTEMS ALONG WEST EUROPEAN COASTS PROEFSCHRIFT TER VERKRIJGING VAN DE GRAAD VAN DOCTOR IN DE WISKUNDE EN NATUURWETENSCHAPPEN AAN DE KATHOLIEKE UNIVERSITEIT TE NIJMEGEN OP GEZAG VAN DE RECTOR MAGNIFICUS PROF DR J H G I GIESBERS VOLGENS BESLUIT VAN HET COLLEGE VAN DEKANEN IN HET OPENBAAR TE VERDEDIGEN OP DONDERDAG 30 SEPTEMBER 1982 DES NAMIDDAGS TE 4 UUR DOOR RENÉ PETRUS WILHELMUS MARIA JACOBS GEBOREN TE NIJMEGEN 1982 DRUK DRUKKERIJ VERWEIJ В V , MIJDRECHT Aan mijn ouders en Maarten This thesis includes a range of different aspects related to the ecology of seagrass. Such an approach would not have been possible without the cooperation of a number of graduate students, whom I would like to thank for their practical assistance, not to forget many most stimulating discussions. I have attempted to acknowledge the many people who have contributed in one way or another. Here I would like to thank any I have not mentioned. The research work carried out from November 1975 to November 1979 was centered at the Laboratory of Aquatic Ecology (Catholic University, Nijmegen, The Netherlands) and I am most grateful to the head of the Department and all my former colleagues for their advice, helpful criticism and friendship. 6 COMPONENT STUDIES IN SEAGRASS ECOSYSTEMS ALONG WEST EUROPEAN COASTS CONTENTS 1. History and scope of the research project. 11 References 14 2. R.P.W.M. Jacobs: Distribution and aspects of the production and biomass of eelgrass. Zostera marina L., at Roscoff, France. (Aquat. Bot., 7 (1979): 151-172) 19 Abstract 19 Introduction 19 The study area 20 Material and methods 23 Standing crop and tidal depth Productivity and biomass measurements Results 26 Standing crop in relation to tidal depth Biomass, population dynamics and net production Discussion and conclusions 35 Acknowledgements 38 References 38 3. R.P.W.M. Jacobs and E.S. Pierson: Phenology of reproductive shoots of eelgrass. Zostera marina L., at Roscoff (France). (Aquat. Bot., 10 (1981): 45-60) 41 Abstract 41 Introduction 41 Study area and methods 42 Results 46 Flowering shoot development Spathe development Flower development Discussion 51 Acknowledgements 54 References 54 4. R.P.W.M. Jacobs: Reproductive strategies of two seagrass species (Zostera marina and Z. noltii) along West European coasts. (In: J.J. Symoens, S.S. Hooper and P. Compère (Eds), Studies on Aquatic Vascular Plants. Royal Botanical Society of Belgium, Brussels (1982). pp. 150-155) 57 Summary 57 Introduction 57 7 Life-strategies of the two Zostera species 58 Zostera noltii Zostera marina Application of the theory of r- and K-selection 59 Application of the concept of strategies as proposed by Grime (1979) 60 Acknowledgements 61 References 61 R.P.W.M. Jacobs and T.M.P.A. Noten: The annual pattern of the diatoras in the epiphyton of eelgrass (Zostera marina L.) at Roscoff, France. (Aquat. Bot., 8 (1980): 355-370) 63 Abstract 63 Introduction 63 Locality and methods 64 Results 65 Discussion 71 Acknowledgements 76 References 76 R.P.W.M. Jacobs, P.M. Hermelink and G. van Geel: Epiphytic algae on eelgrass at Roscoff, France. (Aquat. Bot., accepted) 79 Abstract 79 Introduction 80 Study area and methods 81 Results 82 Temporal patterns Colonization and succession Spatial distribution Discussion and conclusions 90 Acknowledgements 92 References 93 R.P.W.M. Jacobs and W.H.T. Huisman: Macrobenthos of some Zostera beds in the vicinity of Roscoff (France) with special reference to relations with community structure and environmental factors. (Proc. Kon. Ned. Akad. Wet., in press) 97 Abstract 97 Introduction 97 Localities and methods 99 Results 100 Description of the fauna! assemblages: numerical analysis Analysis of the community structure Spatial distribution Discussion and conclusions 111 Acknowledgements 115 References 115 8. R.P.W.M. Jacobs, H.H. Hegger and A. Ras-Willems: Seasonal variations in the structure of a Zostera community on tidal flats in the SW Netherlands, with special reference to the benthic fauna. (Proc. Kon. Ned. Akad. Wet., submitted) 119 Abstract 119 Introduction 120 Study area 121 Methods 123 Results 124 1 Structure and dynamics of the vegetation 2 Structure and dynamics of the inhabiting macrofaunal community Quantitative structure and species diversity Species composition and dominance Faunal biomass and dominance Spatial distribution Discussion and conclusions 144 Acknowledgements 148 References 148 9. R.P.W.M. Jacobs, C. den Hartog, B.F. Braster and F.C. Carrière: Grazing of the seagrass Zostera noltii by birds at Terschelling (Dutch Wadden Sea). (Aquat. Bot., 10 (1981): 241-259) 153 Abstract 153 Introduction 153 The study area 154 Material and methods 155 Results 157 Birds grazing on the Zostera noltii bed and their seagrass consumption Feeding behaviour Effect of grazing on seagrass in permanent plots Discussion 167 Acknowledgements 169 References 169 10. R.P.W.M. Jacobs: Ecological effects of the 'Amoco Cadiz' oil spill on the seagrass ecosystem at Roscoff, France. 173 Abstract 173 Introduction 174 Flora 175 Seagrass Epiphytes Fauna 183 Discussion and conclusions 196 9 Acknowledgements 202 References 202 Compilatie van studies over zeegras-oecosysteraen langs West-Europese kusten. Samenvatting. 209 Curriculum vitae 213 Publications 215 Earlier published papers or parts thereof have been reproduced with permission from the copyright holders, i.e. Elsevier Scientific Publishing Company (Amsterdam, The Netherlands), Inter-Research (Halstenbek, Federal Republic of Germany), Koninklijke Nederlandse Akademie van Wetenschappen (Amsterdam, The Netherlands) and the Royal Botanical Society of Belgium (Brussels, Belgium). iO HISTORY AND SCOPE OF THE RESEARCH PROJECT The foundations of the present-day knowledge of the anatomy and taxonomy of the eelgrass. Zostera marina L., were laid as far back as the mid-nineteenth century (e.g. Hofmeister, 1861; Duval-Jouve, 1873; De Lanessan, 1875; Clavaud, 1878; Areschoug, 1878; Schenck, 1886; Sauvageau, 1889, 1890, 1891; Ascherson and Graebner, 1907). The study of the plants in their natural habitat, and in relation to biotic and abiotic environmental factors, started at the beginning of the twentieth century (e.g. Ostenfeld, 1908; Joubin, 1909; C.G..I. Petersen, 1913, 1915, 1918; De Beauchamp, 1914; Setchell, 1929, 1933; Harmsen, 1936). Zostera marina, the most widespread seagrass species, is found along the coasts of the northern parts of the Atlantic and Pacific Oceans (Setchell, 1935; Den Hartog, 1970). The species came to be known under several common names (e.g. French, zostère; Dutch, zeegras; German, Seegras; Danish, baendeltang; etc.) and was found to be of both practical and nutritional value (see McRoy and Helfferich, 1980). The suspected ecological importance of eelgrass (see Petersen and Boysen-Jensen, 1911) was confirmed by the locally catastrophic effects of the "wasting disease" in the nineteenthirties: entire beds in the North Atlantic coastal waters were destroyed and this resulted in fundamental changes in the substratum and the animal communities. The history, cause and environmental effects of the locally total disappearance of eelgrass have been described in numerous reports (e.g. Cotton, 1933; Cottam, 1933; Taylor, 1933; H.E. Petersen, 1933, 1934; Fischer-Piette, 1934; Marsille, 1935; Stevens, 1936; Renn, 1936; Tutin, 1938; Lami, 1938; Blegvad, 1944; Wilson, 1949). The slow and gradual recovery of the meadows was not complete until well into the fifties (Butcher, 1935; Cottam, 1945; Cottam and Munro, 1954). The history of the disease and the effects in Danish waters in relation to changes in the environment were reviewed by Rasmussen (197 7). Three years after the appearance of the first comprehensive monograph of the seagrasses of the world (Den Hartog, 1970), an International Seagrass Workshop was held in Leiden (The Netherlands), 11 which aimed at stronger cooperation in further seagrass research. In addition to a number of review papers (Den Hartog, 1973; McRoy and McMillan, 1973; Kikuchi and Pérès, 1973; Fenchel, 1973; Burrell, 1973), the Workshop group presented recommendations for further research on seagrass ecosystems (McRoy, 1973). The stimulating effect of the Workshop found concrete shape in a series of coordinated publications (McRoy and Helfferich, 1977; Phillips and McRoy, 1980; special issues of Aquatic Botany (Vol. 1(2), 1975; Vol. 2(2), 1976; Vol. 7(2), 1979) and Aquaculture (Vol. 4(2), 1974; Vol. 12(3), 1977)) in addition to a considerable list of reports on divergent topics related to seagrasses. Since its foundation in 1973, the research projects at the Department of Aquatic Ecology of the Catholic University of Nijmegen (The Netherlands) have concentratefl on the structure, function and dynamics of macrophyte-dominated aquatic communities (see Den Hartog, 1976b). Emphasis was laid on the communities dominated by nymphaeids (Lammens and Van der Velde, 1978; Van der Velde, 1979; Van der Velde et al., 1979; Van der Velde and Van der Heijden, 1981), Zannichellia spp. (Van Vierssen, 1982a, b, c; Van Vierssen and Van Wijk, 1982) and Ruppia spp. (Verhoeven, 1975, 1979, 1980a, b; Verhoeven and Van Vierssen, 1978a, b). The communities dominated by the seagrasses Zostera marina and Z. noltii Hörnern, were investigated from 1975 to 1979 by the author in a research project aimed at the study of their structural and functional aspects, and was financed by the Netherlands Organization for the Advancement of Pure Research (ZWO). The study areas were located in the Netherlands, i.e. the Dutch Wadden Sea and the Oosterschelde in the SW, and in Brittany (France). Seagrasses are the only angiosperms completely adapted to a permanently submerged life in the marine environment.