Palaeolimnology in eastern and southern Australian estuaries

Abstract

Palaeolimnology has been widely used in freshwater environments, providing information for policy development and legislation (Bennion and Battarbee 2007; Battarbee and Bennion 2011). However, application of palaeolimnology in coastal environments remains challenging (Cooper 2010). The application of palaeolimnological techniques in coastal ecosystems was pioneered by Cooper and Brush (1991), Juggins (1992), Andren (1999) and Kerfoot et al. (1999). These methods have required some adaptations (Cooper 2000; Cooper et al. 2004), but have been effectively utilised in many Northern Hemisphere estuaries. For example, studies of the Baltic Sea (Kauppila et al. 2005; Clarke et al. 2006; Weckstrom 2006; Tuovinen et al. 2010), Chesapeake Bay (Cooper and Brush 1993; Cooper 1995, 1999, Cooper et al. 2004), Florida Bay (Wachnicka et al. 2010, 2011) and the Pearl River estuary in southern China (Zong et al. 2010) have produced results that provide information useful to managers. Yet, in the Southern Hemisphere, and in particular Australia, application of palaeolimnological methods in coastal environments remains in its infancy (Saunders and Taffs 2009). In general, palaeolimnology in Australia is underutilised, yet offers many possibilities for a continent that has experienced dramatic landscape change over a short period of time that is rarely fully documented. In particular, information on Australian estuaries is urgently required to assist management actions where there are substantial population pressures and multiple conflicting uses of coastal environments (Saunders and Taffs 2009). However, applying palaeolimnological techniques to Australian estuaries is particularly problematic because of the paucity of information on Australian estuary functioning. While it is well understood that estuaries are highly dynamic ecosystems (Cooper 1999), the variability of estuarine function across climatic zones is still being actively researched (Eyre and Balls 1999; Bowen and Valiela 2008). Australian estuaries function quite differently to their Northern Hemisphere counterparts (Davis and Koop 2006), hence palaeolimnological methods largely developed in the Northern Hemisphere need to be applied with some caution in Australia. The greatest cause of these differences is that rainfall frequency is much lower, with episodic rain events controlling chemical and biological functioning (Davis and Koop 2006). Hence, average water residence time is often higher than in less variable ecosystems with equivalent freshwater inputs, resulting in a dominance of internal nutrient cycling. J. Tibby (&) Geography, Environment and Population, University of Adelaide, Adelaide, SA 5005, Australia e-mail: john.tibby@adelaide.edu.au