University of Wollongong Theses Collection University of Wollongong Theses Collection University of Wollongong Year Studies on the biomass, diversity and nutrient relationships of macroalgae and seagrasses in Lake Illawarra, New South Wales, Australia Karin Rutten University of Wollongong Rutten, Karin, Studies on the biomass, diversity and nutrient relationships of macroalgae and seagrasses in Lake Illawarra, New South Wales, Australia, PhD thesis, School of Earth and Environmental Sciences, University of Wollongong, 2007. http://ro.uow.edu.au/theses/22 This paper is posted at Research Online. http://ro.uow.edu.au/theses/22 Studies on the biomass, diversity and nutrient relationships of macroalgae and seagrasses in Lake Illawarra, New South Wales, Australia A thesis submitted in fulfillment of the requirements for the award of the degree DOCTOR OF PHILOSOPHY from UNIVERSITY OF WOLLONGONG by KARIN RUTTEN SCHOOL OF EARTH AND ENVIRONMENTAL SCIENCES - 2007 - Thesis Declaration I, Karin Rutten, declare that this thesis, submitted in fulfillment of the requirements for the award of Doctor of Philosophy, in the School of Earth and Environmental Sciences, University of Wollongong, is wholly my own work unless otherwise referenced or acknowledged. The document has not been submitted for qualifications at any other institution. Karin Rutten - II - Table of Contents Thesis Declaration ........................................................................................................................ II Table of Contents......................................................................................................................... III List of Figures.............................................................................................................................. VII List of Tables................................................................................................................................. X List of Plates...............................................................................................................................XIV Abstract ......................................................................................................................................XVI Publications arising to date from this study..............................................................................XVIII Acknowledgements ..................................................................................................................XVIII CHAPTER 1 Introduction ......................................................................................................1 1.1 General Introduction..........................................................................................................1 1.2 Statement of the Problem .................................................................................................2 1.3 Thesis Aims and Objectives..............................................................................................3 1.4 Thesis Outline ...................................................................................................................3 1.5 Study Site - Lake Illawarra ................................................................................................4 1.5.1 Site Description ................................................................................................. 4 1.5.2 Catchment Land Use ........................................................................................ 4 1.5.3 Climate .............................................................................................................. 6 1.5.4 Lake Entrance Conditions ................................................................................. 7 1.5.5 Nutrient Enrichment........................................................................................... 8 1.5.6 Macroalgal Blooms.......................................................................................... 11 1.5.7 Macroalgal Harvesting .................................................................................... 12 1.6 Summary.........................................................................................................................13 CHAPTER 2 Literature Review ...........................................................................................14 2.1 Introduction .....................................................................................................................14 2.2 Ecology of Aquatic Macrophytes.....................................................................................15 2.2.1 Seagrasses ..................................................................................................... 16 2.2.2 Macroalgae...................................................................................................... 18 2.2.3 Macrophyte Biomass....................................................................................... 20 2.2.4 Environmental Limitations on Macrophyte Growth ......................................... 21 2.3 Photosynthesis in Aquatic Macrophytes .........................................................................23 2.3.1 Availability of Light........................................................................................... 24 2.3.2 Carbon............................................................................................................. 27 2.4 Nutrients..........................................................................................................................30 2.4.1 Nutrients Required by Macrophytes................................................................ 31 2.4.2 The Phosphorus Cycle.................................................................................... 32 2.4.3 The Nitrogen Cycle.......................................................................................... 34 2.5 Nutrient Uptake by Macrophytes.....................................................................................36 2.5.1 Phosphorus Uptake......................................................................................... 37 2.5.2 Nitrogen Uptake .............................................................................................. 37 2.5.3 Growth of Macroalgae in Culture .................................................................... 38 2.5.4 Nutrient Uptake Kinetics.................................................................................. 39 2.5.5 Nutrient Limitation ........................................................................................... 43 2.5.6 Nutrient Uptake from Sediment....................................................................... 44 2.5.7 Factors Affecting Nutrient Uptake ................................................................... 45 2.6 Macrophyte Tissue Nutrient Concentrations...................................................................46 2.6.1 Effect of Nutrient Enrichment .......................................................................... 51 - III - 2.6.2 Stoichiometric Ratios of C : N : P.................................................................... 52 2.6.3 Stable Isotopes of C and N ............................................................................. 55 2.7 Local Macrophyte Studies...............................................................................................59 CHAPTER 3 Materials and Methods ..................................................................................60 3.1 Introduction .....................................................................................................................60 3.2 Methodology used for the Studies of Macrophyte Biomass, Distribution and Diversity in Lake Illawarra ...................................................................................................................60 3.2.1 Site Selection .................................................................................................. 60 3.2.2 Sample Collection and Preservation............................................................... 61 3.2.3 Macrophyte Sample Preparation..................................................................... 63 3.2.4 Identification of Macrophytes .......................................................................... 63 3.2.5 Sediment Sample Preparation ........................................................................ 64 3.2.6 External Laboratory Analysis and Quality Control Samples ........................... 64 3.2.7 Statistical Analyses ......................................................................................... 66 3.3 Methodology used for the Experimental Growth in Culture of Chaetomorpha linum .....67 3.3.1 Sample Collection ........................................................................................... 67 3.3.2 Preconditioning and Culture Media................................................................. 67 3.3.3 Media Preparation........................................................................................... 69 3.3.4 Experimental Apparatus.................................................................................. 70 3.3.5 Preparation of Plant Material........................................................................... 70 3.3.6 Experimental Design ....................................................................................... 71 3.3.7 Calculations and Statistics .............................................................................