There are now more fish, underwater plants and macroinvertebrates in the Coorong and Lower Lakes than there has been since the Millennium Drought, new research shows.
Scientists say significant reductions in both salinity and nutrient levels following the floods have triggered a boom in aquatic, plant and other life.
According to the latest research and monitoring, there has been a substantial increase in fish including congolli, black bream, greenback flounder and yelloweye mullet. This is benefitting birds and larger fish that feed off the smaller fish species.
The Coorong’s underwater plants, many of which were almost lost from the system during the Millennium Drought, are recovering and provide an important habitat for fish and are a vital food source for birds.
Importantly, the South Lagoon, which was severely impacted by the drought, appears to also be bouncing back with reduced salinity and increased animal life including macroinvertebrates that are extending further south into the lagoons.
The scientists have been engaged through the Healthy Coorong, Healthy Basin program to analyse water quality and nutrients in the Coorong and Lower Lakes.
They form part of a scientific advisory group that provides advice on water delivery and water for the environment by collecting and analysing fish, vegetation, invertebrate and water quality data.
Their research is on show at the Healthy Coorong, Healthy Basin Science Forum in Goolwa on Tuesday 16 May. Attendees can participate and provide feedback during a Coorong Restoration Roadmap workshop on the day. While it is a free event, registration is essential via https://hchbforum.eventbrite.com.au/
Quotes
Attributable to Susan Close
This important scientific work is yielding wonderful news for the ecology of the lakes, and I thank everyone involved in collecting and analysing the data.
While the floods have provided a much needed boost to the Coorong and Lower Lakes, it must be sustained into the future through sufficient environmental flows.
The Coorong and the Lower Lakes were the absolute last refuge for birds and other animals throughout the drought and we must continue to ensure it is there when the next big dry spell hits.
This is we are working with the Albanese government to deliver the Murray-Darling Basin plan in full, including the 450 gigalitres for environmental flows promised to South Australia but so far not delivered.
Attributable to Assoc. Professor Jason Nicol, Senior Research Scientist, SARDI
We have observed positive changes in the plant community since the recent flood.
The reduced salinity and extended high water levels in the Coorong resulting from the flood event have provided favourable conditions for the submergent plant community with the highest biomass recorded since the Millennium Drought.
Attributable to Assoc. Professor Qifeng Ye, Principal Scientist, SARDI
Species numbers doubled in the South Lagoon following the reduction of salinity to less than 60 grams per litre.
The increase in fish biomass will also now benefit the many fish-eating birds and larger fish within the waters.
Attributable to Assoc. Professor Luke Mosley, University of Adelaide
Early indications from the data we’ve collected post the big flood is that there has been marked reductions in salinity and nutrient levels in most of the Coorong, particularly the South Lagoon.
These conditions should enable a wider diversity of invertebrates and aquatic plants to recolonise the southern region of the Coorong, which could further improve water quality as they oxygenate the sediment and remove nutrients.
Attributable to Professor Sabine Dittmann, Flinders University
The macroinvertebrate community found near Noonameena has now become more similar to the community previously confined to the Murray Mouth region.
This brings multiple benefits, such as a potential for bioremediation of the sediments through bioturbation by the larger worms, and the provision of food for shorebirds and fish preying on them.
