The effects of hydroperiod on macroinvertebrate assemblages of temporary and permanent floodplain wetlands and how this relates to taphonomy and the palaeoecological record

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 could be used to reconstruct historical waterbody hydroperiod over time in future palaeoecological studies.