A “Milestone Report” No. 8, 2018, entitled Assessment of the status and options for recovery of prawns & estuarine biodiversity in the Noosa River by Greg Skilleter (Uni. Qld. & Murdoch Uni.), Dylan Moffitt (Uni. Qld.) and Neil Loneragan (Murdoch Uni.) has come to QSN. This report of data from 1998 to 2018 was auspiced by the Noosa Biosphere Reserve Foundation.
After publication of this report, the ABC ran a story
https://www.abc.net.au/news/2020-08-05/river-noosa-biodiversity-decline-dredging/12522984
Marine scientist Dr Ben Diggles, in an email dated 19 August 2020 has cautioned thus:
“I refer you to a recent ABC report on the health of the Noosa River. … The key quote that was brought to my attention for comment was from Noosa Biosphere Reserve Foundation chair, Rex Halverson, who said “many people had been misled by the A- water quality rating the Noosa River received, which was amongst the best in Queensland”.
This is correct. The reality is one that scientists have known for some time. The healthy waterways rating method is only an overview and does not measure several critical parameters that indicate ecosystem health. In the case of the Noosa River (and most likely other waterways in S.E. QLD), chemical contamination from the catchment and benthic anoxia (oxygen depletion in the sediments) brought about by nutrient and sediment loading/eutrophication are likely to be the main problems driving this decline in small benthic animals. The waterways rating system does not directly measure these parameters and thus tends to underestimate actual declines in ecosystem functioning, as demonstrated by the loss of oyster reefs and the many small animals in the benthic sediments which make up the bottom end of the food chain.
When the bottom of the food chain is declining 60-95%, regardless of your waterways rating, the upper food chain (commercially and recreationally important fish, crabs) must shrink by at least the same amount. There are no free lunches.
Thus the vital importance of active restoration such as the shellfish reef restoration we are trialling in Pumicestone Passage and which we would like to undertake on a wider basis for shellfish reefs throughout Moreton Bay. The fact that University of Sunshine Coast monitoring shows we can generate at least 10 times more fish in the restored trial area compared to baseline in only 3 years demonstrates that if we work to restore the impacted lower end of the food chain, the fish will look after themselves (i.e. the upper food chain will respond).”