Coorong starved of water, shorebirds starved of food

By Associate Professor David Paton.

An edited version of this opinion piece was published in the Advertiser 11th February 2016

One of the goals of the Murray Darling Basin Plan is to deliver a healthy Coorong. Five years into the implementation of this plan, the Coorong is still far from healthy, particularly for shorebirds. Instead, the shorebirds using the Coorong are in dire straits. The food resources that these birds use are still depressed, so much so that the birds spend up to 90% of their day foraging. Dead shorebirds are found along the Coorong’s shorelines, particularly on the islands where there are no foxes to scavenge carcasses. Such carcasses are skinny. The birds have clearly starved. If the birds are struggling to survive in January, then they will struggle even more with shorter day lengths in February and March. Finding enough food to fatten prior to migrating northwards in autumn will be hard. Productive habitats in the Coorong are clearly not being provided. Consequently, our obligations under international migratory bird agreements are not being met.

Associate Professor David Paton with dead shorebirds recorded around the Coorong in January
Associate Professor David Paton with dead shorebirds recorded around the Coorong in January

The Coorong is a Wetland of International Importance under the Ramsar Convention, largely because of the tens of thousands of migratory shorebirds that visit the area during our summer. These birds, including various sandpipers, breed in the northern hemisphere during our winter, before migrating south along the East Asian‑Australasian Flyway, arriving in southern Australia in spring. Once settled in places like the Coorong, the birds replace their feathers over summer before fattening for the 10,000 km flight back to their northern breeding grounds, stopping several times along the route to ‘refuel’.

Dead shorebirds are found along the Coorong’s shorelines…. Such carcasses are skinny. The birds have clearly starved.

Managing these birds is challenging because it involves cooperation between all countries along the flyway. Australia has international migratory bird agreements with Japan, China and the Republic of Korea that require each country to manage the habitats used by the migratory shorebirds. Despite these agreements, these birds have continued to decline, with some species, like the Curlew Sandpiper, now listed as critically endangered under Australia’s Environment Protection and Biodiversity Conservation (EPBC) Act. The cause is predominantly flagged as a loss of suitable habitat along the flyway, particularly around the Yellow Sea, where extensive areas of mudflats are being developed for human use. However, Australia has also failed to maintain and provide critical, productive mudflats for a pivotal stage in the birds’ journey.

Recovery of the Coorong is possible by addressing inadequate water levels in the southern Coorong during spring. Adequate water levels are needed to allow Ruppia tuberosa – an aquatic plant fundamental to the ecosystem – to flourish. If covered with water, these plants reproduce and increase in abundance, producing seeds and turions, which form part of a shorebird’s diet. In the 1980s, there were around 20,000 Ruppia tuberosa seeds per square metre around the margins of the southern Coorong – today there are merely 200, just 1% of the historical levels.

We need to stop kidding ourselves that the Murray Darling Basin Plan will deliver a healthy Coorong

Adequate River Murray flows over the Barrages throughout spring and into summer can maintain water levels in the southern Coorong. The volumes needed are of the order of 1000 gigalitres per month and were usually met until we extracted significant volumes of water from the River for human use. For the last decade the barrages have been closed for part if not all of spring leaving Ruppia tuberosa exposed prematurely. At present, the Commonwealth Environmental Water Holder has around 1500 gigalitres at his disposal, and other demands and constraints limit his capacity to help the Coorong. So, only in the occasional years when floods occur in spring will conditions be suitable for Ruppia now.

We need to stop kidding ourselves that the Murray Darling Basin Plan will deliver a healthy Coorong. The plan has always been inadequate to meet the Coorong’s water level requirements, and doubly so given the plan ignores climate change. Alternatives are urgently needed, such as a barrier across the Coorong to hold back water in the southern Coorong during spring. If there is no resolve to fix the water level issue (and to do this now), then the Coorong should be managed as a different ecological entity, and our shorebirds should be compensated by constructing productive habitats in other areas. Both State and Federal government agencies have been aware of this issue for some time but have failed to act. The shorebirds are paying the ultimate price for this inaction. Perhaps it is time for an independent body free from politics to take control.