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Australasian Plant Conservation

Originally published in Australasian Plant Conservation 18(4) March - May 2010, p 9-10

Wetlands of the Murray-Darling Basin: EPBC Act threatened ecological communities?

Gina Newton
Department of the Environment, Water, Heritage & the Arts, Canberra. Email: gina.newton@environment.gov.au

Under the EPBC Act

Two wetland areas of the
Lower Murray–Darling to Sea
ecological community. Photos: SA Murray Darling Basin NRM Board.

Areas of significant wetlands form part of two aquatic ecosystems currently being assessed for listing as threatened ecological communities under the Environment Protection and Biodiversity Conservation Act 1999 (EPBC Act). The aquatic ecosystems are the Lower Murray–Darling to Sea and the Wetlands of the Darling Basin. Listing would confer national conservation benefits, including an increased public awareness for these highly productive, biodiverse environments. The EPBC Act focuses on nationally significant aspects of the environment and provides for the identification and protection of matters of National Environmental Significance. Nationally threatened species and ecological communities are one of several such matters.

The listing process for threatened ecological communities begins with the receipt of nominations from the public. These are strategically assessed by the advisory Threatened Species Scientific Committee for suitability and a Proposed Priority Assessment List is forwarded to the Environment Minister for approval each year. Based on the Minister’s determination, this list then becomes the Finalised Priority Assessment List.

For assessment of the ecological communities on the finalised list, the Department relies heavily on input and data from experts, including those from State/Territory agencies. Expert consultation also generally includes holding a technical workshop. More information on the process is available at <www.environment.gov.au/biodiversity/threatened/index.html>.

A first for riverine wetlands

The Lower Murray–Darling to Sea was originally nominated in 2007 as the Coorong and Lower Lakes. This was expanded and included on the August 2008 Finalised Priority Assessment List as The Lower Murray River and associated wetlands, floodplains and groundwater systems from the junction of the Darling to the sea. This fitted well with the Minister’s nomination conservation theme for that year of ‘rivers, wetlands and groundwater dependent species and ecosystems of inland Australia’.

The advisory committee agreed that there was greater conservation benefit in expanding from the Coorong and Lower Lakes (already Ramsar listed and thus a matter of National Environmental Significance) to include the region of upstream influence and impacts, as well as the interdependent groundwater, floodplain and wetland components. The region is considered by experts to be a ‘one of a kind’ system in the national context, and different from other river systems (and the parent rivers) due to its complex features, habitat heterogeneity, and high levels of biodiversity over relatively short distances. The region also has special significance to Indigenous peoples.

Subsequent to the Lower Murray–Darling to Sea assessment, another major wetland focussed ecological community was included on the 2009 Finalised Priority Assessment List, viz. The Wetlands of the Darling Basin (nominated as Macquarie Marshes). This wetland system was frequently flooded prior to regulation and supports (or supported) large breeding events by colonial water birds. Once described, the ecological community is likely to include the terminal wetland systems of the Macquarie Marshes (some 200 000 ha), Narran Lakes (some 30 000 ha) and the Gwydir (formerly one of the most significant semi-permanent wetlands in north-west New South Wales, some 100 000 ha). These wetlands also support a diverse flora, with many species at the edge of their range, as well as very diverse avian and reptilian faunas.

The Lower Murray–Darling to Sea and Wetlands of the Darling Basin ecological communities cover the range of wetland types and forms, from saline to fresh, ephemeral to semi-permanent, and billabongs and lakes to braided channels. All are defined by what’s often considered the so-called ‘maestro’ variable in Australia’s riverine ecosystems—flow, with its associated cycles and flooding regimes.

A new aquatic challenge

The Lower Murray–Darling to Sea is unique in that it represents the first riverine system to be assessed under the EPBC Act as a threatened ecological community. A major challenge for this assessment is that the listing assessment criteria were initially developed for terrestrial vegetation-based systems. To be listed under the EPBC Act, at least one of six criteria contained in the EPBC Regulations 2000 must be met. The criteria determine whether an ecological community is eligible to be listed and under which category (i.e. critically endangered, endangered, or vulnerable).

The applicability of the listing criteria to aquatic systems in general, and the Lower Murray–Darling to Sea was specifically discussed as part of the expert technical workshop held for this assessment process in July 2009.

The workshop found that the listing criteria are generally applicable but may need nuancing when applied to aquatic systems. The workshop determined that the ‘ecological community’ of a large complex aquatic system often consists of sub-units of different biophysical complexity. For example, while the Lower Murray–Darling to Sea ecological community may be considered as a ‘constructed’ system (i.e. comprised of several smaller ecological communities), its components are functionally connected. Thus, criteria should still be applied at the whole system level, not at the sub-unit level.

The high variability of aquatic systems—temporal, spatial, natural and anthropogenic—combined with the interplay of surface and ground waters, compounds the challenge and requires consideration and some degree of flexibility with respect to interpretation of the listing criteria and their concomitant ‘thresholds’. It was considered essential that a quality ‘baseline’ (or benchmark state) be determined, keystone or foundation species identified, and key indicators of decline (as related to threats) established.

Importantly for wetlands and their associated floodplains, it was recognised that the assessment should take into account the fact that these component-systems can transition between aquatic (wet) and terrestrial (dry) states.

National importance and conservation benefit

Both the Lower Murray–Darling to Sea and Wetlands of the Darling Basin ecological communities include several Ramsar listed wetlands. The former community includes the Coorong and Lakes Alexandrina and Albert, Riverland (including the Chowilla floodplain), and Banrock Station Wetland Complex. The latter community includes the Macquarie Marshes, Gwydir and Narran Lake Nature Reserve.

Australia currently has 65 Ramsar wetlands that cover around 7.5 million hectares. Ramsar wetlands are those that are representative, rare or unique wetlands, or are important for conserving biological diversity. These are included on the List of Wetlands of International Importance held under the Ramsar Convention.

Australia also has more than 900 ‘nationally important wetlands’ (as based on meeting one of six criteria). These are wetlands that are a good example in a particular area, an important habitat for native species, or that have outstanding heritage or cultural significance. Nationally important wetlands are listed on the Directory of Important Wetlands (see www.environment.gov.au/water/topics/wetlands/database/diwa.html).

While Ramsar listing of wetlands affords conservation benefit, inclusion of these wetland systems within an overarching threatened ecological community offers complementary conservation benefit beyond the sites, including connectivity to other system elements such as important upstream influences. A threatened ecological community listing can also provide broader national conservation benefit spatially, for example only approximately nine per cent of the Macquarie Marshes is currently Ramsar listed.

Next steps

The assessments for the Lower Murray–Darling to Sea and Wetlands of the Darling Basin wetland communities will take up to three years, with the former due by September 2011 and the latter by September 2012. The assessment process will include public and targeted consultation to assist with the determination of listing eligibility.

The technical workshop report for the Lower Murray–Darling to Sea is scheduled to be available for public comment on the Department’s website by April 2010. The assessment process for the Wetlands of the Darling Basin has just commenced and a technical workshop is planned for late 2010. Another technical workshop, focussing on thresholds associated with the listing criteria and ‘condition’ as they relate to complex aquatic systems and the Lower Murray–Darling to Sea is planned for April 2010.