The Effects of Land Use on Stream
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THE EFFECTS OF LAND USE ON STREAM COMMUNITIES IN HIGHLAND TROPICAL NIGERIA A thesis submitted in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Ecology at the University of Canterbury, New Zealand by Danladi Mohammed Umar University of Canterbury 2013 Contents Acknowledgements ...........................................................................................................iv Abstract ..............................................................................................................................vi Chapter 1 General introduction ............................................................................................................ 1 Chapter 2 Illustrated guide to freshwater invertebrates of the Mambilla Plateau .............................. 24 Introduction ........................................................................................................................ 24 Methods.............................................................................................................................. 25 Freshwater invertebrates .................................................................................................... 29 Taxonomic classifications .................................................................................................. 31 Key to the aquatic macroinvertebrates of the Mambilla Plateau ....................................... 32 Chapter 3 Response of benthic invertebrates to a land use gradient in tropical highland streams ... 103 Introduction ...................................................................................................................... 103 Methods............................................................................................................................ 105 Results .............................................................................................................................. 109 Discussion ........................................................................................................................ 122 Chapter 4 Riparian land use and its relationship between benthos and litter decomposition in Nigerian highland stream .................................................................... 133 Introduction ...................................................................................................................... 133 Methods............................................................................................................................ 135 Results .............................................................................................................................. 140 Discussion ........................................................................................................................ 150 Chapter 5 Food web structure in tropical highland stream ecosystems ........................................... 158 Introduction ...................................................................................................................... 158 Methods............................................................................................................................ 161 Results .............................................................................................................................. 166 Discussion ........................................................................................................................ 174 Chapter 6 General discussion and conclusions................................................................................. 186 Summary of findings........................................................................................................ 186 ii | P a g e Appendix 1 Summary of mean physico-chemical and taxa data of 55 streams surveyed in my study on Mambilla Plateau. ..................................................................................................... 198 Appendix 2 Summary of invertebrates for 55 streams surveyed between October 2009 and March 2010 on Mambilla Plateau. .......................................................................... 213 Appendix 3 Mean taxa abundance of stream benthic invertebrates surveyed between October 2009 and March 2010 on Mambilla Plateau. .................................................... 233 Appendix 4 Density of consumers mostly collected from stones and wood in the nine case study streams on Mambilla Plateau. .............................................................................. 237 Appendix 5 Reprint of published article derived from chapter two; studies on the effects of light traps on dragonflies on Mambilla Plateau. ......................................................... 240 Appendix 6 Reprint of published article derived from chapter three; an application of the maximum convex sum algorithm in determining environmental variables that affect Nigerian highland stream benthic communities. ............................ 241 iii | P a g e Acknowledgments I would like to thank all those who helped me come this far. Naming all of them would not be easy due to time and space. I sincerely wish to appreciate the efforts of my supervisory team for their advice and guidance. I would like to thank my principal supervisor, Prof. Jon Harding who contributed in the development of the project concept after visiting the study site in Nigeria, gave me extra coaching in the field and laboratory analysis, reviewed the entire thesis and administered financial support. I thank Assoc. Prof. Hazel Chapman, my co-supervisor who contributed in many ways towards the success of this project. I would like to thank the Vice Chancellor of the Gombe State University, Prof. Abdullahi Mahadi who inspired me and also gave all the moral and financial backing to be able to accomplish this task. The contributions of Prof. M. J. Winterbourn were incredible for identifying the fauna of the Mambilla Plateau, and reviewing the manuscripts and giving useful comments. I appreciate all the support received from Prof. Paula Jameson the head of School of Biological Sciences, University of Canterbury. I wish to thank Prof. Angus McIntosh for all the support he rendered. Pete McHugh assisted in data analyses and a book in biostatics and Kate McHugh provided maps of the study sites. I thank Trent Hoover who provided the drawing of the Nigerian Crab in chapter two. I appreciate the contributions of Milen Marinov for drawing maps of study sites, and contributions towards manuscript preparation published in the International Dragonfly Fund 2012. I thank Matt Walters for publishing chapter two of this thesis as a photographic guide book. I wish to thank Mohammed Thaher and Tadao Takaoka for the collaborative research we had which led to the paper we jointly published. I wish to thank my fellow PhD colleagues; Francis Burdon who assisted in some of the analyses and Kristy Hogsden who provided many useful suggestions. I am grateful to Stephen Pohe who assisted in editing the manuscripts and to Hayley Stoddart and Elizabeth Graham who assisted in the isotope processing and analysis. I thank Linda Morris for sending me all the field gear needed for the field work. My thanks also go to Nicole Lauren-Manuera who secured the MAF and Bio-security permits to import samples in to New Zealand and for exporting samples to UC Davis stable isotope facilities in the USA and Nicki Judson who gave lots of administrative assistance. I wish to express my appreciation to Hamish Grieg, Jon O’Brien, Tanya Blakely, Helen Warburton, Amanda Klemmer, Robyn White, Aude Thierry, Lorna Deppe and Jonathan Bray. To all the members of the FERG past and present, I say a big thank you. My profound appreciation goes to Stephen Moore (Manaaki Whenua Landcare Research, New Zealand) who provided some of the photos used in chapter two. My appreciation goes to iv | P a g e Dr Mohammed Musa, Omar Yusuf and Abdullah Alshareef who have been very supportive. Others who helped during the field work in sampling all the streams include Misa Zubairu, Hammadu Adamu, Mairiga and the industrial training students attached to the Ngel Nyaki field station. Funding for this project came from Gombe State University, Educational Trust Fund Nigeria and the University of Canterbury New Zealand. I wish to thank my family for missing me all these years I have been studying in New Zealand. Finally, it has been tasking but rewarding experience studying the highland tropical streams. I have learnt a lot about these ecosystems and have gained a wide range of field, laboratory and analytical skills in the course of this project. I am thankful to have had such an opportunity. v | P a g e Abstract Globally, stream invertebrate communities have been shown to respond to habitat degradation as a result of land use changes. The effects of land use changes on stream communities have been well documented in temperate regions, however, their effects in the tropics are relatively unknown, particularly where land use activities can differ markedly (e.g., tea, maize and Eucalyptus plantations). To understand how land use affects tropical highland Nigerian stream communities, I surveyed 55 second and third order streams across four land use categories, ranging from continuous tropical montane forest to intensive crops/pasture. Streams were sampled in the dry season (October to March) for physico-chemical parameters (i.e., temperature, pH, conductivity, turbidity, current velocity, channel morphometry and riparian characteristics)