Department of Environment and Agriculture School of Science Seasonality and nutrient-uptake capacity of Sargassum spp. in Western Australia Tin Hoang Cong This thesis is presented for the Degree of Doctor of Philosophy of Curtin University May 2016 DECLARATION To the best of my knowledge and belief this thesis contains no material previously published by any other person except where due acknowledgment has been made. This thesis contains no material which has been accepted for the award of any other degree or diploma in any university. Signature:…………………… Date: ………………………… ii ACKNOWLEDGEMENTS Many people and organizations have helped me during this Ph.D. program. I would first like to express my deep gratitude to all of them. I would like to acknowledge the Department of Foreign Affairs, Australian Government for sponsoring me by the Australian Awards to undertake a Ph.D. study at the Department of Environment and Aquatic Science, Curtin University, Perth, Western Australia. I also thank the International Sponsored Students Unit liaison officers Julie Craig, Kristen Soon, Chris Kerin, and Hoa Pham, as without their valuable assistance my research would have been very difficult. I wish to express my warm and sincere thanks to both of my supervisors, Professor Dr. Ravi Fotedar and Dr. Michael O’Leary, for their fantastic guidance, support and encouragement that they have provided throughout my Ph.D. studies. They have worked tirelessly to guide, correct, and advise me to keep all my objectives on track. I am indebted to Iain Parnum and Malcom Perry of the Centre for Marine Science and Technology (CMST), and Rodrigo Garcia, Peter Fearns, and Mark Broomhall of the Remote Sensing and Satellite Research Group, Department of Imaging and Applied Physics, Curtin University for their significant support during the field study trips and in remote-sensing techniques. I would also like to thank staff of the Western Australia Herbarium, Rottnest Island Authority, Department of Wildlife and Parks (previously known as Department of Environment and Conservation) for their kind assistance in access to their database, the study sites, and sampling permits. Many thanks to Anthony Cole, Simon Longbottom, and Rowan Kleindienst for their dedicated assistance during both field and laboratory studies. I would like to thanks Thang Le for his assistance in line drawing several illustration figures. Special thanks to my best friend and great diving buddy, Anthony Cole, for spending time participating in most of the sampling trips, English correction, and time enjoying beers. I would also like to thank my delightful mentors around the global ocean including Dr. Michael Lomas (Bigelow Laboratory for Ocean Sciences, USA), Dr. Varis Ransi (National Oceanic and Atmospheric Administration–NOAA (USA), Prof. Joji Ishizaka (Nagoya University, Japan), Prof. Matsumura Satsuki (National Research iii Institute of Far Seas Fisheries, Japan), Dr. Sophie Seeyave (The Partnership for Observation of the Global Oceans–POGO), Dr. Shovonlal Roy (The University of Reading, UK), A/Prof. Dr. Pham T. N. Lan, MSc. Mai V. Pho, Dr. Luong Q. Doc, Dr. Nguyen Q. Tuan, Dr. Duong B. Hieu (Hue University of Science, Vietnam), Mr. Tong P. Hoang Son (Institution of Oceanography, Vietnam) for their on–going support and invaluable advice. In particular, I would like to acknowledge A/Prof. Dr. Ton T. Phap for his valuable instruction during my early scientific career as I am sure I wouldn’t be where I am now if I hadn’t listened to him. Furthermore, I cannot forget many of my colleagues and friends for their encouragement in my early academic life. Some of them can be named, such as Mrs. Phan T. Hang, Lilian Kruge, Nguyen T. T. Hieu, Dr. Trinh D. Mau, Dr. Bui B. Dang, but there are many who are not listed here. I would also like to thank all my fellow postgraduate students and colleagues in Curtin University including Ong M. Quy, Dinh Q. Huy, Mai V. Ha, Pham D. Hung, Bui T. Ha, Le T. Ky, Ardiansyah Ali, Ilham Alimin, Irfan Ambas, Suleman, Himawan Achmad, Muhammad A. B. Siddik, and Nguyen V. Binh at Curtin Aquatic Research Laboratory for their happiness and support during the years spent there. Beyond all, my deepest thanks go to my family for their support, encouragement, and interest in my work. Especially, I thank my wife, Nguyen T. Bich Ngoc, who patiently supported me when I was nearly exhausted. She dedicated her time, energy and love to looking after our daughter, Hoang B. Chau, and the family, so that I could fully concentrate on my studies and career at each step. Thanks to my parents, my parents in-law, all my brothers and sisters for their dreams, hopes, emotional support, and prayers. I would like to state from the bottom of my heart that I could not have finished my Ph.D. program without the support of those mentioned above. iv PREAMBLE The thesis consists of nine chapters. Chapter 1 presents a comprehensive literature review on satellite remote-sensing of marine habitats mapping and the importance of Sargassum spp., taxonomy, distribution, reproduction, phenology effects of environment factors and nutrient-uptake capacity, all under the influence of the seasonality of Western Australia (WA). Chapter 2 introduces and provides an overview of the thesis with detail of the site selection criteria and the description of the study sites. This chapter also presents justification for the study and states the research questions, followed by the aims and objectives of the study. Chapter 3 to 8 address the main objectives of the thesis. These chapters have been either presented at national or international conferences, seminars or independently submitted to peer-review scholarly journals for publication. The full list of attended conferences, seminars, and published journals is provided on pages xxvii‒xxix. Chapter 3 presents the spectral response of marine submerged aquatic vegetation (SAV) habitat along the WA coast. This chapter provides a comprehensive study on spectral reflectance profiles of SAV species and is an important pre-requisite study to meet the objectives in Chapters 4 and 5. Chapter 4 identifies and maps the marine SAV in the shallow coastal water using WorldView-2 (WV-2) satellite data. This chapter also presents methods and interprets the results when using WV-2 on classification and building SAV distribution maps including Sargassum spp. Chapter 5 presents the remoted-sensing mapping of Sargassum sp. distribution around Rottnest Island, WA using high spatial resolution WV-2 satellite data. Chapter 6 describes the life cycle and ecology of Sargassum species in WA by presenting the primary data on distribution, growth rate, and reproduction of the species. This chapter documents the life cycle of Sargassum spinuligerum along the WA coast based on field observations and laboratory works. This base line knowledge of the biology and ecology of the local species gives vital information on the seasonality of Sargassum that is described in Chapter 7. v Chapter 7 illustrates the seasonal variations in water quality as a driver of seasonal changes in Sargassum at the study site. Based on the findings of the seasonality study in chapter 7, a laboratory experiment was conducted which is described in chapter 8. The chapter 8 explores the effects of nutrient and initial biomass on the growth rate and nutrient-uptake of S. spinuligerum thus providing essential information on the aquaculture potential of Sargassum. The thesis is completed with a general discussion of key findings and conclusions in Chapter 9. This chapter also summarizes all of the main results of this study, and discusses the findings in a broader context. The chapter ends with several recommendations for potential studies on the topic. vi ABSTRACT Sargassum is one of the most diverse genera of the marine macroalgae, is distributed worldwide, and is mainly dominant in tropical and sub-tropical shallow waters. The Sargassum spp. play a major role in forming the SAV (submerged aquatic vegeteation) habitats with high productivity and biomass to maintain healthy coastal ecosystems. To date, there have been a limited number of studies on seasonal variation on Sargassum communities and no studies on the ecological characteristics of growth, reproduction, and the life cycle of Sargassum spp. undertaken along the subtropical zone of the WA coast. Moreover, there have been no studies using multi- spectral satellite remote-sensing to map Sargassum, canopy macroalgae, seagrasses, and its associated habitats along the WA coast. Recently, Sargassum species have also been proposed as potential candidates for marine culture in the large scale macroalgae farms. However, there are limited reported studies on the cultivation conditions and ecology of Sargassum spp. The main aim of the present study was to investigate the influence of seasonality of water qualities, canopy cover, thallus length, and distribution of Sargassum beds around Point Peron and Rottnest Island, WA. The study presented primary data on growth rate and, reproduction, and documented the life cycle of Sargassum spinuligerum based on field surveys and laboratory works. The spectral reflectance optical data of macroalgae (red, green, and brown), seagrasses, and sediment characteristics in coastal waters were measured in order to support the selection of suitable satellite sensors for different benthos. The feasibility of the WV-2 satellite data for identifying and evaluating classification methods has been validated for mapping the diversity of SAV in coastal habitats. Therefore, assessing the distribution of Sargassum beds using high-spatial resolution WV-2 satellite images from this study could be considered the first such approach. The data on canopy cover, thallus length, biomass, reproduction, and distribution patterns of Sargassum spp. were collected every three months during the period from 2012 to 2014 from four different reef zones along monitored transects. In air spectral reflectance profiles of Sargassum spp. and other SAV species were acquired using the FieldSpec® 4 Hi-Res portable spectroradiometer.