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restoration targets, and developing management plans that accommodate human needs,
while keeping within the limits of the system (Gell 2010). Combined with scenario building,
such time-cognisant approaches allow the development of sustainable water-use options in
the context of changing climate and human needs.
Wetlands, lakes, and other freshwater systems are, by nature, dynamic and responsive to
changes in climate and land use. Water levels fluctuate naturally in response to changing rain-
fall and temperature, and this alters water flow and quality. Intensive agriculture over the last
century, industrialization over the past 200 years or so, and varying levels of land clearance for
cultivation, settlement, and pasture over much longer time periods have impacted freshwater
ecosystems at a range of scales. Often the effects of diffuse pollution, land use change and
acidification build slowly over time. Understanding variability and resilience over long time-
scales is therefore essential to the management of freshwater systems, and in setting realistic
conservation and water quality targets (Gell 2010, Bennion et al. 2011).
A lack of understanding of long-term change can lead to misguided and potentially dam-
aging restoration efforts, and can provide loopholes for evading environmental protection
measures. The Ramsar convention aims to halt and reverse wetland degradation, and the
baseline reference condition for Ramsar sites is usually set when the wetland was listed, or
from anecdotal evidence of past ecosystem condition. However, without long-term data it is
impossible to know whether Ramsar sites are in good condition at the time of their designa-
tion, and a much longer-term perspective is needed if ecological integrity and future resil-
ience are to be restored, as palaeoecological data from the Murray-Darling River Basin (MDB)
in Australia has shown (Gell et al. 2013, Mills et al. 2013). Changes in wetland condition in the
MDB can only be understood in relation to the land-use and settlement history of the area.
The MDB is currently heavily degraded by intensive agriculture and water abstraction (Gell
2010, MacNally et al. 2011, Gell et al. 2012). Major anthropogenic impacts began over 200 years
ago, with land clearance and erosion, accelerating through the nineteenth and twentieth cen-
turies. Industrialization and intensive agriculture have had severe impacts over the past two
centuries, pushing freshwater ecosystems outside of their historic range of variability, and
reducing their resilience to future climate change. The catchment was settled from the 1840s,
and now provides 40% of Australia's agricultural gross domestic product; this has come at
considerable environmental cost. Sediment accumulation rates in many wetlands have
increased 10-100-fold compared with preindustrial rates, associated initially with high rates
of sheep-stocking, and later due to increased erosion and drought. Increased sediment is
associated with high water turbidity, changing the benthic flora and fauna and impacting
filter-feeding organisms. Rainfall reductions are predicted for the MDB, a climate change
hotspot (Giorgi 2006). Declining runoff and river flow will interact with the effects of land use
change in water catchments, increasing the challenge of wetland restoration (Gell 2010). A
reduction in extensive flooding has already led to the die-back of floodplain forests (Mac-
Nally et al. 2011)
The Coorong wetland, a 120 km long coastal lagoon at the mouth of the River Murray, was
designated a Ramsar Wetland of International Importance in 1985. The Coorong wetland was
identified as hypersaline at the time of its Ramsar designation, and as a result, the release of
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