Thursday, July 29, 2021

Dunoon koalas: Water Northern Rivers explores local koala population

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Nan Nicholson, Dunoon and District Gazette

The Dunoon Dam koalas are even more important than first thought. They can help other koala populations to recover robust genetics.

Koala
Photo: Cassie Lafferty, Unsplash

New information has been revealed about the local population of koalas which would be impacted by the proposed 15ML dam at Dunoon.

The Dunoon Dam was taken off the table by Rous County Council in December 2020. The councillors who voted down the dam proposal cited the loss of important ecological systems and fauna habitat, as well as the valuable cultural heritage sites of the Widjabul Wia-bal people.

A new Future Water Plan, without the Dunoon Dam, has been prepared by Rous County Council and released for public comment. Submissions closed on 28 May.

Dr Steve Phillips of Biolink Ecological Consultants says: “The Dunoon koala population has different genetic origins (and is more robust and outbred) than other koala populations to the south and east (which are, in contrast, immunologically compromised and demonstrably inbred).”

The Dunoon koalas thus have lots to offer these other koalas which suffer from high disease levels and associated mortalities, as well as the manifestation of physical traits of inbreeding such as smaller average body sizes and microcephaly.

As far as we can tell, the genetic affinity / origins of the population imply a link to hinterland koala populations of SE Queensland (loosely referred to as the SEQ genome).

We have known about the presence of this special koala population for some time (since at least mid-1990s) but do not yet know such critical things as population size and the full extent of the population’s distribution in the Dunoon area.

Why is the population so special? Because it carries genetic information known to be missing from the coastal populations of Byron, Ballina, and the Richmond River floodplain around Lismore. The progressive or assisted incorporation of genes from the Dunoon koalas into these other populations will increase their overall genetic and immunological fitness and so increase their capacity to resist change.”

Roadkilled koala
This koala, killed by a car, was part of a genetically important population in the Dunoon area that may be able to contribute to the strengthening of the general koala population. Koalas face many threats, including cars and dogs and disease, but the worst is habitat loss. Photo: Nan Nicholson.

The Dunoon Dam would destroy 23ha of koala habitat according to the Terrestrial Ecology Impact Assessment prepared for Rous County Council in 2013. This does not include forest damaged or fragmented by construction works, or peripheral impacts on koalas living around the edges of the impact zone. The forest consists of key koala feed tree species such as Tallowwood, linked by rainforest and regrowth. In addition to habitat loss, koala corridors linking this population to others would also be negatively impacted.

Mitigation is not an option because koalas need these trees now and cannot wait for a regrown forest. Northern NSW koalas could be extinct in less than 30 years if nothing is done to halt ongoing habitat loss.

Dunoon and District Gazette June-July 2021

Water Northern Rivers Alliance represents local groups promoting diverse water options and opposing the Dunoon Dam. https://waternorthernrivers.org/

This article appeared in the Dunoon and District Gazette, June-July 2021.

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