Determining environmental risks to high priority wetlands in the South East

News Title:

Farewell to Bryony Cotterell, CLLMM Centre supports Honours Students project in the Coorong, 60 seconds with Dr Ben Van den Akker, Farewell to Nathan Hartman, CLLMM Science Forum 2024, New Job Opportunity: First Nations Engagement Officer, 60 seconds with Mark Koolmatrie, Goyder to host the One Basin CRC hub in Loxton, 2024 CLLMM Science Forum, Workshop held to improve outcomes in the Ecohydrological conceptual Models and Impact Pathway diagrams Project, 60 seconds with Prof Tom Raimondo, 60 seconds with the Goyder Chair, Jody Swirepik, Update on the Coorong, Lower Lakes and Murray Mouth (CLLMM) Research Centre, Outputs from National Drinking Water Forum in remote First Nations communities Released, Successful Launch of the Coorong, Lower Lakes and Murray Mouth (CLLMM) Research Centre, New Fact Sheet: Translating Yannarumi into Water Resource Risk Assessments, Thank you for all those who attended Science in The Pub!, Join us for the Annual #WORLDWATERRUN from 18-24th March!, Science in the Pub presents "The Coorong, Lower Lakes and Murray Mouth: A journey through droughts and floods.", Join us to Launch the New CLLMM Research Centre, New Project: Analysis of changes in high-intensity rainfall events in South Australia, Goyder Institute 2023 Annual Report Reflects on a Busy Year, New Project: Measuring the impact of Ground Water extractions on Mound Springs in Northern South Australia, CLLMM Research Centre announces a new location in the region, Goyder Institute for Water Research announces new Chair, New Coorong, Lower Lakes and Murray Mouth Research Centre has hit the ground running. , New Project Aims to Understand the Environmental Response of the Coorong to the 2022-2023 River Murray Flood Event, Another New Member of Staff Joins the Goyder Institute, Goyder Institute welcomes another new staff member to the team, New Goyder Institute CLLMM Research Centre Participates in Collaborative Effort to Assist with Environmental DNA Sampling for Threatened Species, Delivering a Better Understanding of Water and Ecological interactions in the Braemar, Stuart Shelf and Northern Eyre Peninsula regions for Sustainable Development, Goyder Institute announces new Director, Goyder Institute welcomes three new staff to the team, Are you the Goyder Institute’s new Communications and Engagement Coordinator?, One Basin CRC holds its first annual event, Messages from the Working together for better drinking water in the bush forum warmly received by Federal Minister Plibersek, Research to continue on environmental impact of recent floods, Help us drive sustainable, innovative and integrated water management, Farewell to Daniel Pierce, Introducing the Goyder Institute's 2023-2026 Strategic Plan, Working together for better drinking water for bush communities, Coorong Research Hub to embark on program to address the effects of climate change, Goyder Institute welcomes two new staff to the team, Supporting climate change resilience in the Coorong, New website goes live, Institute research on show at Healthy Coorong Healthy Basin Science Forum, Goyder Institute takes home back-to-back national R&D excellence awards, Increased flushing vital to Coorong’s long-term health, Ruppia restoration strategy released for southern Coorong, Institute scientists head to River Murray to study environmental impacts of flood, Your chance to contribute to the development of a Resilient Water Future for Greater Adelaide, Institute embarks on a strategic planning refresh, Team Goyder is off and running again for World Water Day, Goyder Institute extended to 2026, New research report reveals pathway to keeping Adelaide’s liveable city status, Chair Prof Barry Hart releases Institute's 2022 Annual Report, A year in review and farewell from our Director, Goyder Institute’s Healthy Coorong, Healthy Basin Research Project wins R&D Excellence Award, How feasible is a water resource rating system for South Australia?, New research project in the South-East kicks off with aerial survey of groundwater, Australian Government announces new Research Hub of the Goyder Institute to support the Coorong, Lower Lakes and Murray Mouth region, Australian Government announces new Research Hub of the Goyder Institute to support the Coorong, Lower Lakes and Murray Mouth region, Chair announcement: Goyder Institute leadership update, Policy changes are needed to better protect environmental water from climate change in the Murray-Darling Basin, Join us as the Goyder Institute prepares to Sweat4Soap once more, Limestone Coast Landscape Board partners with the Goyder Institute to investigate adaptation of the South-East drainage network, New videos showcase research to inform the management of the Coorong, One Basin CRC takes initial steps towards shaping its research program, The South Australian Government and Goyder Institute partner to establish a Water Ambassador, One Basin CRC advances towards establishment with key roles formed, How feasible is land-based aquaculture in South Australia?, Major step towards Institute’s goals achieved as Coorong research concludes, Goyder Institute wins national award for Research Excellence, One Basin CRC to drive a sustainable future for the Murray-Darling Basin, New research project established to explore the feasibility of a water resource rating system, Healthy Coorong, Healthy Basin Program fieldwork wraps up, Goyder Institute research supports $10 million investment to improve shorebird habitat, Floods and recent climate projections highlight the importance of ongoing water reform, Water Resources Conference at the World Expo in Dubai identifies new international partnership opportunities, ONE Basin Cooperative Research Centre takes another important step forward, New project established to inform future urban water management options for Adelaide, In Focus: Research providing knowledge to identify climate adaptation pathways for the Coorong and Lower Lakes region, Running for World Wetlands Day (2 February 2022), 2022 shaping up to be an important year, Great progress towards our third term goals as 2021 draws to a close, In Focus: Research providing knowledge to restore a functioning Coorong food web, Welcome news for the ONE Basin Cooperative Research Centre, Impact of second-term projects continue to ‘flow’, Goyder Institute announced as winner of Australian Water Association’s SA Branch R&D award, The Goyder Institute’s new Interim Director looks to an exciting year ahead, In Focus: Research providing knowledge to maintain viable waterbird populations in the Coorong South Lagoon, Goyder Institute team surpasses its #Sweat4Soap target, Call for participation – water resources conference at World Expo in Dubai, Independent evaluation highlights success of Institute’s second term, Goyder Institute team commits to #Sweat4Soap, In Focus: Research providing knowledge to inform the future management of aquatic plants and algae in the Coorong South Lagoon, In Focus: Research providing knowledge to inform the future management of nutrient levels in the Coorong South Lagoon, Goyder Institute partners in the ONE Basin CRC rebid, IPCC 2021 Report on Climate Change emphasises need for the Goyder Institute to continue to support climate mitigation and adaptation, Goyder Institute showcases its Strategic Plan, Goyder Institute unveils new branding, The Sustainable Development Goals and the Goyder Institute for Water Research, Coorong scientific research project crosses halfway mark, Translating Ngarrindjeri Yannarumi into water resource risk assessments, Reducing fine sediment loads into Adelaide’s coastal waters, Project Coorong’s Science Forum resources now available, From South Lagoon to Siberia: tracking Coorong waterbirds via satellite, Interim management updates, New South Australian Government Climate Change Action Plan provides framework for future research of the Goyder Institute, Institute welcomes new Research Program Manager, ONE Basin CRC bid Stage 2 progresses to final stages, Congratulations Prof McKay – winner Premier’s Water Professional of the Year Award, Second term finishes strong – a year in review from the Director, ANNOUNCEMENT: Goyder Institute welcomes a new Chair and Management Board and Research Advisory Committee representatives, Citizen Science: a key part of the Goyder Institute’s involvement in the HCHB program, Finding ancient water in the outback – new research to support remote communities and enterprises, Vale Professor Peter Teasdale, Goyder Institute partners with the Australian and South Australian governments to restore a wetland of international importance - the Coorong’s South Lagoon, ANNOUNCEMENT: Goyder Institute partners establish the third term of the Institute, ONE Basin CRC bid continues to take shape to address the needs of basin governments, industries and communities, Flow on effects – new tools to support the integrated management of river flows and floodplain infrastructure along the River Murray, Advancing integrated management of Spencer Gulf for economic, social and ecological outcomes, Sea grass communities in Gulf St Vincent to benefit from new stormwater management intervention project, ICE WaRM ceases operations after 15 years of advancing excellence in water leadership across the globe, Agricultural technologies in South Australia survey, Investigations underway to help restore the Coorong, Expert panel recommendations inform changes to groundwater management in the Lower Limestone Coast, ONE Basin CRC bid gains momentum, R&D plan charts course for the year ahead, New research papers outline innovative approaches for water exploration and palaeovalley evolution, Call for expressions of interest – ONE Basin Cooperative Research Centre, A year in review from the Director, Research establishes proof of concept for blue carbon benefits from tidal reconnection of coastal wetlands, New research identifies the importance of healthy coastal habitats for combating climate change, New tools to help growers sustainably expand production in the Northern Adelaide Corridor, New research advances blue carbon opportunities in South Australia, Goyder Institute joins Smart Water Mission to New Zealand, Women changing the future of water, State Government seeks community feedback on Healthy Coorong, Healthy Basin Action Plan, Water managers now able to predict potential foodweb changes associated with floodplain inundation, Women in Water -- visibility matters, SA's droughts are getting worse -- new published research informed by Institute's SA Climate Ready data, G-FLOWS project enters final stages -- characterising the dimensions of a newly discovered paleochannel in the APY Lands, Goyder Institute for Water Research awarded Minister's Award for Excellence, Goyder Institute projects recognised for informing international best practice approaches to Indigenous engagement, Congratulations to Darryl Day -- Water Professional of the Year, Goyder Institute releases findings of independent review of the science underpinning water allocation reductions in the South East, Carbon offsets research to support the State Carbon Sequestration Strategy

Project Partners:

The University of Adelaide, Flinders University, and SARDI

Research Theme:

N/A

Status:

Project Overview

Ewens Ponds, located in the South East of South Australia, are exceptionally clear-water wetlands dominated by macrophytes, which provide critical habitat for protected aquatic species including the critically endangered Glenelg Spiny Crayfish (Euastacus bispinosus).

Regional changes in land use from native vegetation to pasture, and alteration of the hydrology due to increased water extraction, decreased the quantity and quality of groundwater flowing into Ewens Ponds. Episodic occurrence of cyanobacterial blooms and epiphytic algal growth are initial warning signals of deteriorating water quality. Similar freshwater ecosystems have responded in a drastic way to increasing nutrients shifting from a clear-water macrophyte-dominated state to a phytoplankton-dominated state, with concomitant reduction in ecosystem health.

There is increasing concern that pelagic and epiphytic phytoplankton might outcompete macrophytes in Ewens Ponds causing habitat degradation and loss of endangered species. The uniqueness of the ponds and their regional and global importance are motivators for their protection and the maintenance of suitable water quality and flow.

The project aims to identify the most significant threats to high value wetlands in the South East.

  1. Determine the causes of elevated alkalinity and high pH in the South East wetlands. Possible contributory factors to be considered are evapoconcentration of inorganic carbon and depletion of CO2 by algal photosynthesis.
  2. Identify if spikes in the pH of water in these wetlands are a cause for concern, and whether they can be controlled through management of agricultural practices or the operations of the drainage network.
  3. Determine the nutrient budget and sources of nutrients to the clear water ponds of the South East (Ewens Ponds) and model the impact of these nutrients on water quality in the ponds to determine the likely consequences for water clarity and macrophyte growth.
  4. Recommend management guidelines and actions that will reduce the risks to high value wetlands in the South East. 

Progress Update and Key Findings

The key findings related to the risk of regime shift in Ewens Ponds were:

  • Residence time is one of the most important factors controlling future environmental risk. A low residence time of about 9.5 h (flow rate ~1.2 m3 s-1) flushes out of the system pelagic phytoplankton cells that might develop at the surface. Additionally, it avoids stratification, even during the summer, maintaining high oxygenation in the water column. In this highly oxygenated environment there is almost no internal release of phosphorus from the sediment.
  • Nutrient monitoring and bioassay experiments showed that the system is phosphorus limited (e.g. TN:TP ratio of about 420) and nitrogen is extremely high 5.8 ± 0.5 mg L-1. However, sediment flux experiments revealed that there is sufficient total phosphorus available in the sediment to represent a risk. If the flow rate decrease and anoxic conditions develop in the bottom layers, the TP released in 20 days would be able to support pelagic algal growth and reduce light availability for macrophytes of about 50% at their maximum depth of colonization.
  • The combined effect of TP and flow on pelagic phytoplankton development and consequently on light availability for macrophyte growth, were evaluated by modelling. This allowed estimating TP and flushing rate thresholds to maintain clear water and preserve the macrophyte community.
  • The risk in Ewens Ponds is also associated with a possible increase of TP groundwater input in the future. It has been estimated that a spike in nutrients entering the Ponds might be observed between 2026 and 2037. This was obtained relating the calculated water age of the Ponds with the Australian trends in fertilizer use in the last decades. This risk might still be mitigated by flow rates, because, even with increasing TP, pelagic phytoplankton growth will be unlikely to occur if the present flushing rate is maintained.
  • An additional risk for the clear water system conservation is represented by epiphytic algal growth. The development of epiphytic algae might occur at higher flow rate than pelagic algae and it might cover the macrophyte shading the light necessary for their development and compromise ecosystem function. With no limitation of phosphorus the epiphytic algal growth rate could drastically increase up to 5 times the current rates.
  • Many wetlands in the South East are undergoing pressures similar to Ewens Ponds, such as increasing nutrients and flow reduction. For example, several highly valued wetlands, which are groundwater dependent, were identified as being located within groundwater development risk zones in the South East. Information available on total nitrogen (TN) and total phosphorus (TP) observed in South East wetlands were collated and analysed.
  • Conservation planning for Ewens Ponds should focus on maintaining high flow and limiting phosphorus inputs. 

The key findings related to the alkalinity were:

  • Sulfate concentrations in the wetlands studied were low or negligible and would be unlikely to generate large increases in pH. The addition of organic matter caused the available sulfate to be reduced but caused an acidification rather than an alkalinisation of both soil and sediment. Thus, there was no evidence that sulfate reduction was a significant factor in the high pH.
  • Mesocosms experiment results suggested that the high pH is in part due to high carbon dioxide demand from the growing plants coupled with the to slow diffusion of carbon dioxide from the atmosphere which is insufficient to replenish the carbon dioxide sequestered by the plants.
  • The geochemical modelling based on water analyses established that evapoconcentration could cause moderate increases in pH, and in the case of Little Reedy could explain pH up to 9.5. Higher pH in lakes elsewhere has been shown to be associated with low levels of calcium and magnesium.
  • Environmental sampling, mesocosm studies and geochemical modelling indicated that the high pH in the wetlands studied is a natural phenomenon driven by productive plant growth. Despite the high pH, these wetlands support a diversity of plant and animal life. 

Project Impacts

This project provided scientific knowledge to anticipate drastic change in ecosystem dynamic avoiding consequent loss of habitat function for threatened species.

Project outcomes allowed identifying the stressors that interact controlling water clarity and alkalinity in South East wetlands. This enabled support of water quality and conservation management decisions. Additionally, approach and tools adopted can easily be picked up by government and managers to reduce and manage risks. 

Research Outputs

Phytoplankton Growth Dilution Model

Causes of high alkalinity in South East wetlands

Determining environmental risks to Ewens Ponds in the South East

Project News

Contact Us

The University of Adelaide, North Terrace Adelaide South Australia

Postal Address
C/- The Faculty of Sciences, Engineering and Technology, The University of Adelaide Adelaide SA 5005

Twitter Linkedin Vimeo

About Us

Our Work​

Research Outputs

News

Events

Subscribe to eNews