The evolution of a coastal peatland at Byron Bay, Australia: multi-proxy evidence from the microfossil record
Abstract
Coastal peatlands are a rare ecosystem throughout the world. They are highly valued for their ecological importance and functions. However, many coastal peatlands have been degraded and/or destroyed by the development of the coastal plain for urban and agricultural land-uses. At Byron Bay, northern New South Wales, Australia, a large coastal peatland is located parallel to the present coastline. A palaeoecological study was conducted to investigate the use of microfossils in researching peatlands and to identify the coastal evolution of this coastal plain. A 5.2 metre core was retrieved using a Vibracorer. The core was sub-sectioned and analysed for diatoms, phytoliths, pollen and 14C AMS dates were obtained. The dates show that the surface peat has been forming since before 5000 cal. years BP. Lithological and dating results indicate that sea level has been stable throughout that time allowing the continuous development of the peatland. Prior to 5000 cal. years BP sea level was slightly higher than present and estuarine mud was deposited at the study site. Diatom preservation was adequate in the upper parts of the core to retrieve environmental information and provide indicative trends at depths in the core. The diatom results show that Eunotia and Nitzschia genus were dominant in the peat layer indicating the freshwater, acidic nature of the peatland. Nitzschia fonticola was the dominant diatom preserved in the estuarine mud beneath the peat layer indicating the robust nature of the diatom frustule. During the time of peat deposition, pollen and phytolith records indicate that this area was a forested peatland. In most recent times it was dominated by Myrtaceae tree species with Cyperaceae and Restionaceae as the dominant peat forming vegetation. This study shows that a multi-proxy approach using microfossils such as diatoms and phytoliths, can be successfully used to identify the environmental history of coastal peatland sites. Such baseline information is essential to improve the management and conservation efforts within these rare ecosystems.