The wetlands of the Glenelg Hopkins region are a crucial component of the natural environment and contribute significantly to the ecological, social and agricultural health of the region. The catchment includes more than 5,400 wetlands, covering 73,000 hectares (ha) or 3% of the region’s area. This represents 14% of Victoria’s total area of wetlands and 44% of the state’s total number of wetlands[i].
Wetlands of the Glenelg Hopkins region have been acknowledged as key areas for conservation under a number of international agreements. Lake Bookaar, near Camperdown, is recognised under the Ramsar agreement as a wetland of international importance[ii] and several other wetlands fall within the flyways of bird species recognised under international treaties (Japan-Australia Migratory Bird Agreement, China-Australia Migratory Bird Agreement and Republic of Korea-Australia Migratory Bird Agreement). In addition, there are four Important Bird and Biodiversity Areas (IBAs) and 16 wetlands that are listed in the Directory of Important Wetlands of Australia (DIWA).
Many wetlands in the region have been lost or degraded to various extents. Since European settlement, many wetlands have been drained, reducing their extent and connectivity[iii]. They have also been affected by grazing, cropping and the establishment of tree plantations.
The region’s wetlands are integral to healthy functioning ecosystems in the landscape, regulating water quality and contributing to biodiversity. They receive runoff, absorb and filter floodwaters, replenish groundwater reserves and act as direct surface water supplies[iv]. Wetlands play a significant role in storing sedimentary organic carbon, and account for a substantial portion of carbon stocks with the Glenelg Hopkins region[v].
The region’s wetlands range from large and permanent freshwater lakes to small and ephemeral (non-permanent) freshwater meadows. Each wetland type has unique plant diversity and provides habitat for a range of birds, frogs, reptiles, fish and invertebrate species.
Wetlands are among the ecosystems most vulnerable to climate change. The most evident impact on wetlands within the Glenelg Hopkins region will come from changes to rainfall and increased temperatures. Decreased rainfall will impact hydrological regimes and extreme weather events (heatwaves, droughts, storms and floods) will become more frequent and intense.
In spite of their vulnerability it is recognised that many wetlands are highly resilient by nature. For example, seasonal herbaceous wetlands (SHW) are adapted to drying out for long periods of time and although dry periods are increasing and becoming more frequent, they have still shown an ability to recover quickly when wetting occurs. However, the recovery and adaptive capacity of the region’s wetlands will be related to the connectivity of wetlands and wetland complexes.
Since the release of the RCS, Seasonal Herbaceous Wetlands (Freshwater) of the Temperate Lowland Plains have been listed as critically endangered under the Environmental Protection and Biodiversity Conservation Act 2012 (Cwlth). Seasonal herbaceous wetlands are isolated freshwater wetlands that are usually seasonally inundated through rainfall and then dry out, so surface water is not permanently present. Because they are not always visible and are reliant on rainfall, they are particularly prone to degradation from land use change and vulnerable to reductions in rainfall under climate change.
The region’s low-lying coastal wetlands and shallow wetlands that rely on direct rainfall are most likely to be affected by climate change. A future hotter and drier climate in the Glenelg Hopkins region will reduce many wetlands in size, convert some wetlands to dry land or shift them from one wetland type to another. Climate change and rising sea levels will likely lead to a significant loss and degradation of wetlands and associated biodiversity[vi].
All wetlands types within Glenelg Hopkins region currently face a range of threats that will be exacerbated and augmented by climate change. The two wetland types that will be most vulnerable to climate change are the coastal and seasonal herbaceous wetlands.
[i] Glenelg Hopkins CMA, Glenelg Hopkins regional wetlands status report, Glenelg Hopkins CMA, Hamilton, 2006.
[ii] Glenelg Hopkins CMA, Glenelg Hopkins regional catchment strategy 2003-2007, Glenelg Hopkins CMA, Hamilton, 2003.
[iii] Glenelg Hopkins CMA, Glenelg Hopkins regional wetlands status Report, Glenelg Hopkins CMA, Hamilton, 2006.
[iv] Glenelg Hopkins CMA, Glenelg Hopkins regional wetlands status report, Glenelg Hopkins CMA, Hamilton, 2006.
[v] P Carnell, C Ewers, E Rochelmeyer, R Zavalas, B Hawke, D Ireodiaconou, J Sanderma, P Macreadie, The distribution and abundance of ‘blue carbon’ within Glenelg Hopkins, Deakin University, Warrnambool, 2015.
[vi] C Jin, B Cant, C Todd, Climate change impacts on wetlands in Victoria and implications for research and policy, Arthur Rylah Institute for Environmental Research Technical Report Series no 199, Department of Sustainability and Environment, Heidelberg, Victoria, 2009.