EFFECTS OF ATMOSPHERIC POLLUTANTS ON EPIPHYTIC TERRESTRIAL ALGAE ASMIDA ISMAIL A thesis submitted in fulfilment of the requirements for the degree of Doctor of Philosophy and the Diploma of Imperial College London Division of Biology, Department of Life Sciences, Imperial College London, Silwood Park Campus, Ascot, Berkshire, SL5 7PY, United Kingdom. January 2012 1 Abstract Unlike their counterparts lichens and bryophytes, the role of epiphytic terrestrial algae as indicators of atmospheric pollution is not widely explored by biologists. This thesis investigates the relationship between the two factors using green algae due to their high degree of exposure to pollutants and their potential for rapid response to environmental change. We looked into how contemporary atmospheric pollutants influence the growth, abundance and diversity of epiphytic terrestrial algae in the UK. Approaches included surveying algal abundance along a local (150m) transect adjacent to a point source of ammonia pollution, and a similar survey along a much longer transect (50km) spanning urban and rural locations. Controlled application of nitrogen and sulphur gaseous pollutants was also undertaken, initially on a small scale using quadrats on tree trunks, and on a larger scale using the facility operated by the Centre for Ecology & Hydrology at Whim bog, south of Edinburgh. The response of selected algae to the same chemicals under laboratory conditions was also investigated. Through the five separate but related field and laboratory experiments, it is concluded that nitrogen (N) deposition is probably the most important factor controlling the growth of green epiphytic algae as opposed to other pollutants such as sulphur dioxide. Local high N deposition is markedly stimulatory to the growth and sustainability of Desmococcus olivaceus. It also contributes to the dominance of this and other nitrophilous algae and suppresses acidophyte species. Algae exposed to wet N deposition show greater species diversity compared to dry N deposition. In general Desmococcus spp. were much more tolerant of pollution than Trentepohlia spp. Long-term experiments at both Whim bog (Edinburgh, Scotland) and Silwood Park (Ascot, England) showed that a reduced form of N was more stimulatory to algal growth than oxidized N. In contrast, over short-term exposure periods, oxidized N in general was more beneficial to algal growth than the reduced form. The same contrasting result between short and long term exposure was also observed where bisulphite, as a proxy for sulphur dioxide, did not show any toxicity to algae under the short-term study but was damaging when exposed over a longer period. 2 DECLARATION OF OWN WORK I confirm that this thesis: Effects of atmospheric pollutants on epiphytic terrestrial algae is entirely my own work, conducted under the supervision of Dr Simon Archer. Where any material could be construed as the work of others, it is fully cited and referenced, and or with appropriate acknowledgement. No part of this research has been submitted in the past, or is being submitted, for a degree or examination elsewhere. The input of my supervisor to the research and to the thesis was consistent with normal supervisory practice. I grant copyright of this thesis to Imperial College London. January 2012 Name of student : Asmida Ismail Name of supervisor : Dr Simon Archer 3 ACKNOWLEDGEMENTS First and foremost I would like to thank my supervisor Dr Simon Archer for his endless support, encouragement, continued interest, uplifting advice and for always being there when I need some guidance. I am also indebted to Dr Jeffery Bates who has been with me during the early years of my PhD candidature. Without both of them, I could never have achieved so much. Thank you for always believing in me. I would like to extend my gratitude to Professor David John of Natural History Museum who has gone to a great length to help in algal species identification. His expertise and sharp eyes have broadened my knowledge on terrestrial algae. I could never leave out Dr Fabio Rindi, formerly servicing at National University of Galway, Ireland and currently working in Italy. His interest in my research project particularly in the identification of terrestrial algae, has always injected a positive outcome. While conducting the very tiring and challenging fieldworks, I have met many great people. Among them were Dr Lucy Sheppard and Dr Ian Leith of Centre for Ecology and Hydrology, Edinburgh who has given me much useful advice during my fieldwork at Whim ombrotrophic bog. Their friendliness made the work so much easier even when the weather has been torturous to us. Also thank you to managers, rangers and staffs of Kensington Gardens, Putney Heath, Epsom Common, Holmwood Common, Ebernoe Common, Hesworth Common and Crown Estate office for the permission to carry out my fieldwork in their respective areas. To all my friends, Dr Nurazura Adam, Dr Sofia Khalid, Dr Tariq, Farida, Firesenai, Henri, Ki- Jung, Maswa, Sue and many others who has been with me along the way, thank you for cheering up my life. I would also like to thank Ministry of Higher Education Malaysia (MOHE) and Universiti Teknologi MARA (UiTM) for sponsoring my PhD tenureship. To my parents and siblings who have always looking up on me, thank you very much. Also to my dearest husband, Dr Ahmad Ismail and my daughter Farah Alia who has been through thick and thin, just so I could reach for my lifetime achievement – my PhD. My endless love is all I could offer. 4 TABLE OF CONTENTS Abstract ....................................................................................................................... 2 DECLARATION OF OWN WORK .......................................................................... 3 Acknowledgements .................................................................................................... 4 Table of Contents ........................................................................................................ 5 List of Figures ............................................................................................................. 10 List of Tables .............................................................................................................. 13 CHAPTER 1 : GENERAL INTRODUCTION 1.1 Atmospheric pollution ....................................................................................... 14 1.1.1 History of air pollution ........................................................................... 14 1.1.2 General influence of gaseous atmospheric pollutants to ecosystems ............................................................................................. 15 1.2 Aims and objectives of this study ...................................................................... 18 1.3 Overview of the thesis ....................................................................................... 19 1.4 Literature review ................................................................................................ 20 1.4.1 Atmospheric pollutants .......................................................................... 20 1.4.1.1 Types of pollutants ................................................................ 23 1.4.1.2 Source of pollutants ............................................................... 27 1.4.1.3 Negative effects of pollutants ................................................ 28 1.4.1.4 Current air pollutant status .................................................... 31 1.4.2 Algae ...................................................................................................... 32 1.4.2.1 Algae in general ..................................................................... 32 1.4.2.2 Algae and habitat quality ....................................................... 34 1.4.2.3 Habitats and substrata of terrestrial algae .............................. 36 1.4.2.4 The importance of algae ........................................................ 39 CHAPTER 2 : GENERAL METHODS 2.1 Systematic algal collection ............................................................................. 42 2.2 Microscopy ........................................................................................................ 43 2.3 Algal quantification ........................................................................................... 43 2.4 Algal identification ............................................................................................ 44 2.4.1 Algal species description ....................................................................... 44 2.5 Pollutant concentration determination ............................................................... 49 51 2.6 Bark pH .............................................................................................................. 5 CHAPTER 3: EFFECTS OF NH3 AND OTHER NITROGENOUS GASES EMITTED FROM A PIG AND POULTRY FARM ON EPIPHYTIC TERRESTRIAL ALGAE 3.1 Introduction ........................................................................................................ 52 3.1.1 Effects of NH and other nitrogenous gases on the ecosystem 3 community ............................................................................................. 54 3.1.2 Effects of N-deposition on lower plants ................................................ 57 3.1.3 Hypotheses ............................................................................................. 58 3.1.4 Aims and objectives ..............................................................................