Novel Approach for the Classification of Habitats in Tropical Estuaries Exposed to Urban and Industrial Development
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ResearchOnline@JCU This file is part of the following work: Trave, Claudia (2019) Novel approach for the classification of habitats in tropical estuaries exposed to urban and industrial development. PhD Thesis, James Cook University. Access to this file is available from: https://doi.org/10.25903/2qhj%2D3x39 © 2019 Claudia Trave. The author has certified to JCU that they have made a reasonable effort to gain permission and acknowledge the owners of any third party copyright material included in this document. If you believe that this is not the case, please email [email protected] Novel approach for the classification of habitats in tropical estuaries exposed to urban and industrial development Thesis submitted by Claudia Trave Bachelor of Biological Sciences, Università degli Studi di Milano, Italy Master of Marine Biology (Tropical), Stockholm University, Sweden For the degree of Doctor of Philosophy (Natural and Physical Sciences) – Marine Biology College of Science and Engineering James Cook University, Townsville, Australia December 2019 ii Acknowledgements A person once said to me “I was looking for an answer and I found a better question”. I feel this quote embodies well the journey I have been on over the last four years. It has truly been a transforming experience where both myself and my work have progressively changed and adjusted to better fit new perspectives and circumstances and achieve the final goal of completing this PhD and developing new knowledge on the topic of sustainable coastal development. Today I can finally look back and see how much I have learned, improved, and grown as a researcher and as a person through this work. If I have arrived this far is also thanks to the many people in my life who have helped (sometimes in mysterious ways) and supported me throughout this journey. First and foremost, to my Advisors Dr. Nathan Waltham and Prof. Marcus Sheaves for joining me in this adventure and for providing insight, guidance, encouragement, and invaluable help. I want to thank you for helping me learn and improve while pursuing my passion, and for all the time you have dedicated to this PhD project. To the staff in the College of Science and Engineering, the Graduate Research School and the International Student Support: thank you for your great assistance, particularly with helping me overcoming the hurdles in the past year and final rush, and for always finding an alternative or solution. You guys are the best. A big thank you goes to all my friends, colleagues, and volunteers who helped me in the field and in the lab. It has been a pleasure working with you and sharing those long yet fulfilling days in the mud measuring, recording, photographing, and running after critters (especially crabs). I would like to extend special thanks my parents for their unwavering support, help and advice throughout this 4-year journey. Se insisto e resisto, raggiungo e conquisto. I wouldn’t have made it here without you. Special thanks also go to Ricky Gray, for his patience, presence and support, for lending an ear, being an attentive listener and for providing always grounding advice. And finally, I want to thank all my friends in Townsville, Italy, USA and Belgium, and acknowledge the Rotary Club of Mundingburra, Rotary community of Australia, and the Townsville Scottish Community Inc. for always cheering me from the side-lines and for their great support, moral or otherwise. And thank you also for the wine. iii iv Statement of the contribution of others This thesis was made possible thanks to the supervision of Doctor Nathan Waltham and Professor Marcus Sheaves, who provided guidance for the development of the study design, selection of appropriate methodologies and techniques, and editorial comments on the thesis. Assistance in data analysis and interpretation was provided by Prof. Marcus Sheaves, Dr. Nathan Waltham, Dr. Christine Buelow, Dr. Carlo Mattone, Dr. Laura Brannelly, and César Herrera. Editorial assistance for content and English language/syntax was given by Dr. Leone Bielig, Dr. Fabio Trave, and Dr. Alessandra Mazzoni, who have contributed to the improvement of this work with their comments and feedback. Data-collection was performed with the help and contribution of volunteers from the Science for Integrated Coastal Ecosystem Management lab (formerly Estuary and Coastal Wetland Ecosystems Research group), students from James Cook University and personal friends. In alphabetical order: Alessandra Mazzoni, Alexia Dubuc, Caitlin Lennard, Chi Wei, Connor Gervais, Danilo Malara, Greg Hamblin, Jakob Fries, Julia Koburg, Kevin Crook, Kyana Pike, Megan Ogburn, Monica Morin, Ricky Gray, Rucha Kulkarni, Sneha Prakasamma, Tiane Armstrong, and Tom Stevens. Centre for Tropical Water and Aquatic Ecosystem Research (TropWATER), James Cook University also provided some funding to attend conferences. Financial support was provided by the James Cook University Postgraduate Research Scholarship and thanks to the tuition free contribution from the College of Science and Engineering and the Graduate Research School (James Cook University). Costs associated with this project were supported by internal research funding from the Graduate Research School (James Cook University). Every reasonable effort has been made to gain permission and acknowledge the owners of copyright material. I would be pleased to hear from any copyright owner who has been omitted or incorrectly acknowledged. v vi “Sorry, sorry! No monkey!” Kinabatangan River Guide, Malaysia 1993 viii Abstract In response to the increasing rate of coastal development in tropical regions managers are calling for ecosystem-based management strategies to assist with decisions regarding further urban and industrial expansion. Knowledge on the composition, status, and function of the ecosystems exposed to development is necessary and helps to ensure the conservation/restoration of natural habitat and the ecological services and functions they provide. Such information however is often not available at the scale at which managers perform their work, does not include artificial features as components of the ecosystem, and its acquisition is frequently limited by timelines and budgets. Additionally, the patterns of change and cumulative effects of incremental development in coastal ecosystems – particularly in tropical regions – are far from having been fully characterised and are still being investigated. To address these gaps in methodology and information I have developed a rapid assessment tool specific to intertidal foreshore mapping that can assist in gathering information on the structural complexity and status of an ecosystem at a scale applicable to managers and ecological researchers. Such information is not only essential as a baseline for effective planning of new developments but is also applicable for restoration of impacted areas. This novel approach to the classification of coastal ecosystems is achieved by assessing structural attributes (vegetation, sediment type, and artificial features) which can be combined in easily identifiable units called ‘structural habitats’, a factor essential for mapping, quantification, and planning. This classification scheme for structural habitats can be applied to a variety of coastal ecosystems and has the advantage of being rapid, inexpensive, and versatile enough to align to other existing classifications or to be integrated in environmental impact assessment protocols. I tested and applied this classification scheme to the assessment of the habitat composition and mosaic configuration of four tropical estuaries located in Townsville and the broader region surrounding the city (Queensland, Australia). I chose these estuaries as they represent varying levels of urban development, with a mix of natural and hard engineering structures distributed along their linear length. Their location in the Great Barrier Reef World Heritage Area makes this research particularly relevant and essential for the broader context of GBR reef resilience as well, being part of a complex larger seascape. The protection and restoration of the GBR and the connected coastal ecosystems are in fact key targets in the Reef 2050 Long-Term Sustainability Plan (Reef 2050 Plan) prepared by the Australian government. The results obtained indicate estuaries that are largely modified by urban and industrial expansion have a higher level of habitat ix complexity compared to those less exposed to development. I identified over seventy-nine different structural habitats across the four estuaries. Most habitats (81%) are characterised by the presence of one or more artificial features (e.g. rock walls, stormwater drains) and found predominantly in the more urbanised areas. This high variability in habitat composition is linked to the progressive development carried out in these ecosystems, and probably in coastal tropical regions more broadly. The distribution and extent of the different habitats across the estuaries revealed how incremental urban development has likely contributed to the formation of a complex and varied shoreline mosaic, particularly so in the more urbanised estuaries compared to the low-development estuaries that still have much natural shoreline vegetation present. Next, I assessed the species composition of the macrofauna present in each type of structural habitat and determined patterns of spatial distribution in three of the four estuaries. Using data collected over two years, I ran classification trees which revealed how