The effects of hydroperiod on macroinvertebrate assemblages of temporary and permanent floodplain wetlands and how this relates to taphonomy and the palaeoecological record Dale Richard Campbell, BEnvSc&Mgt(Hons) School of Environmental Sciences Charles Sturt University December 2020 A thesis submitted according to the requirements for the Degree of Doctor of Philosophy at Charles Sturt University, Thurgoona, New South Wales Example of a temporary wetland (top) and permanent wetland (middle) on the Ovens River floodplain. Photo of Ovens River, Victoria, Australia (bottom). i Certificate of Authorship I hereby declare that this submission is my own work and to the best of my knowledge and belief, understand that it contains no material previously published or written by another person, nor material which to a substantial extent has been accepted for the award of any other degree or diploma at Charles Sturt University or any other educational institution, except where due acknowledgement is made in the thesis. Any contribution made to the research by colleagues with whom I have worked with at Charles Sturt University or elsewhere during my candidature is fully acknowledged. I agree that this thesis be accessible for the purpose of study and research in accordance with normal conditions established by the Executive Director, Library Services, Charles Sturt University or nominee, for the care, loan and reproduction of the thesis, subject to confidentiality provisions as approved by the University. Name: Dale Campbell Signature: D. Campbell Date: 18.12.2020 ii Acknowledgements To my supervisors: A/Prof. Paul Humphries (Charles Sturt University), Dr Nicole McCasker (Charles Sturt University) and A/Prof. Michael Reid (University of New England) thank you for your supervision and assistance. I would like to thank Dr Wayne Robinson and Mr Simon McDonald for statistical advice. Dr Daryl Nielsen for his statistical advice and insight into wetlands and their fauna. Advice was greatly appreciated. Also, Mrs Deanna Duffy for creating the maps of the Ovens River floodplain used in this study. Finally, I would like to thank my family and friends for your support and help, I could not have done this without you. This study was conducted in accordance with the National Parks Act 1975 and the Flora and Fauna Guarantee Act 1988, permit number 10008752. This research was supported by the Australian Government Research Training Program (RTP) Scholarship. iii Abstract Live macroinvertebrate sampling provides a snapshot in time of wetland assemblages present, whereas subfossils in sediments integrate patterns over seasons, years, and even longer periods. Subfossils found in wetland sediments, although potentially rich in biological and ecological information, are, however, unevenly distributed, and incomplete, due to decomposition, post-mortem transport, burial, compaction, and other chemical, biological, or physical activities. Researchers have only recently begun to consider how preservation biases may influence some of the apparent patterns within the palaeoecological record. The aim of this study was to determine how the live macroinvertebrate assemblages in temporary and permanent floodplain wetlands translate to the death assemblages, and by inference, how well the live assemblage is represented in the death assemblage found in sediment traps and surface sediments. Macroinvertebrates were sampled via live sampling, sediment traps (macroinvertebrate remains) and from the top 20 mm of wetland surface sediments (subfossils). Sampling was undertaken in 12 permanent and 12 temporary wetlands on the Ovens River floodplain, Victoria, Australia. Results show macroinvertebrate assemblages of temporary and permanent wetlands are significantly different, and that the macroinvertebrate assemblages collected vary depending on the sampling method undertaken, predominately due to the loss of soft-bodied genera, and the gain of macroinvertebrates, e.g. Terrestrial genera. A large proportion of the live macroinvertebrate assemblage (particularly Diptera and Coleoptera) translated into the sediment traps (remains assemblage), which then translated into the wetland surface sediments as subfossils, strengthening their use in future palaeoecological studies. Many macroinvertebrates demonstrate potential to be indicators of hydroperiod, as some only occur in a specific wetland type. Therefore, it is possible to determine hydroperiods of waterbodies using the presence/absence of certain macroinvertebrate genera. Further, this thesis suggests that macroinvertebrate subfossils iv could be used to reconstruct historical waterbody hydroperiod over time in future palaeoecological studies. v Table of Contents Certificate of Authorship .............................................................................................................. ii Acknowledgements..................................................................................................................... iii Abstract ...................................................................................................................................... iv Chapter 1: General Introduction ................................................................................................... 1 1.1 Floodplains and wetlands ................................................................................................... 1 1.2 Hydroperiod ....................................................................................................................... 3 1.3 Macroinvertebrates ............................................................................................................ 7 1.4 Palaeoecology (remains and subfossil macroinvertebrates) ............................................... 13 1.5 Taphonomy ...................................................................................................................... 14 1.6 Thesis aims ....................................................................................................................... 15 1.7 Thesis structure ................................................................................................................ 16 Chapter 2: Effects of hydroperiod on the macroinvertebrate assemblages of temporary and permanent floodplain wetlands ................................................................................................. 18 2.1 Introduction ..................................................................................................................... 18 2.2 Methods ........................................................................................................................... 23 2.2.1 Study area ............................................................................................................................ 23 2.2.2 Field methods....................................................................................................................... 29 2.2.3 Laboratory methods............................................................................................................. 34 2.2.4 Statistical methods ............................................................................................................... 35 2.2.4.1 Effect of hydroperiod on the temporal patterns of physical-chemical properties of the water in floodplain wetlands .................................................................................................... 36 2.2.4.2 Effect of hydroperiod on temporal patterns of total abundance, richness, individual Genera abundances and assemblage composition of live macroinvertebrates in floodplain wetlands .................................................................................................................................... 36 2.2.4.3 Relationship between physical-chemical properties and assemblages ........................ 38 2.2.4.4 Identifying macroinvertebrate indicators of hydroperiod ............................................ 38 2.3 Results ............................................................................................................................. 39 2.3.1 Effect of hydroperiod on the temporal patterns of physical-chemical properties of the water in floodplain wetlands ........................................................................................................ 39 2.3.2 Effect of hydroperiod on temporal patterns of total abundance, richness, individual Genera responses and assemblage composition of live macroinvertebrates in floodplain wetlands ........................................................................................................................................ 43 2.3.3 Relationships between the physical-chemical properties and macroinvertebrate assemblages .................................................................................................................................. 56 2.3.4 Identifying macroinvertebrate indicators of hydroperiod ................................................... 57 2.4 Discussion ........................................................................................................................ 61 vi 2.4.1 Effect of hydroperiod on the temporal patterns of physical-chemical properties of the water in floodplain wetlands ........................................................................................................ 62 2.4.2 Effect of hydroperiod on macroinvertebrates in floodplain wetlands ................................ 63 2.4.3 Relationships