The Vasse Wonnerup Wetlands System (VWWS) is a shallow waterbody, intermittently-open to the sea, which is located near the town of Busselton, Western Australia. The wetlands are an internationally recognised Ramsar listed site and supports more than 30 fish species and more than 37,500 waterbirds from 90 different species.
The wetlands are highly modified and experience extreme seasonal variations in environmental conditions, creating a highly complex system with interactions between water, plants and animals from the catchment, the wetlands themselves and the sea. As a result, management of the VWWS needs to be underpinned by a sound scientific understanding of ecosystem structure and processes, while also aligning with social and political realities and community expectations.
Key gaps in knowledge include: “Nutrients – Where do they come from?”, “Who eats what in the Vasse Wonnerup?”, and “How does the community value the wetlands?”
There has been considerable management, research and community efforts aimed at addressing some of the above issues, and most recently through the Vasse-Taskforce.
In collaboration with agencies, local governments and leading researchers, the South West Catchments Council (SWCC) has identified key knowledge gaps and management questions for the VWWS.
Through funding from the Australian Government’s National Landcare Programme, SWCC has enabled and facilitated the establishment of an innovative collaborative research program, led by Murdoch University and Edith Cowan University. This research program also receives invaluable in-kind support from the Department of Water, the Department of Parks and Wildlife, Curtin University and Southern Cross University. Broadly, this program, which commenced in February 2015 and runs until June 2018, aims to help managers design effective strategies to protect the core community values and ecological functioning of the system.
“The program enmeshes the ecological and social sciences and aims to advance our knowledge to provide an integrative solution to the management of this wetland system” Dr Jane Chambers, Program Leader, Murdoch University.
The research program comprises a suite of projects, including three PhDs, one Masters and two Honours students, to answer key priority management questions for the wetland system.
Three main research areas and associated PhDs include:
1. “Identifying nutrient and organic matter sources in an impacted coastal wetland system” PhD project with Edith Cowan University (Rosh.McCallum, Glenn Hyndes, Kathryn McMahon), Murdoch (Jane Chambers) and Southern Cross University (Bradley Eyre, Joanne Oakes).
2. “Constructing a quantitative and predictive food web for the VWWS” PhD project with Murdoch University Murdoch (Sian Glazier, Fiona Valesini, James Tweedley, Steve Beatty), Edith Cowan University (Glenn Hyndes).
3. “How does the community values, perceive and understand the VWWS?” PhD project with Murdoch University (Shivani Purushothaman, Kate Rodger, Halin Kobryn, Jane Chambers), Edith Cowan University (Joanna Pearce).
The research program will address some of the gaps in current knowledge about the wetland’s function and structure, as well as community values, attitudes and perceptions of the VWWS and its management. Importantly, whilst focussed on a single ecosystem, the integrative nature of the program’s research projects will be broadly applicable to other estuaries and wetlands.
The overall research program’s results will enable a better understanding of its threats, management issues and; will assist in developing appropriate adaptive management strategies, mitigation measures and on-ground actions, as well as identify key indicators to be monitored that will inform management and promote increasingly informed decisions.
To date, the three PhD students have been in the field collecting samples and speaking to key stakeholders about the values of the wetlands.
PhD Project 1: Mud, glorious mud
Edith Cowan University PhD student, Rosh McCallum is tracing the sources of organic matter and nutrients in the Vasse Wonnerup Wetlands near Busselton. The nationally significant Ramsar-listed Vasse Wonnerup wetlands experience algal blooms, low dissolved oxygen, fish kills and obnoxious odours. Excess nutrients, either dissolved in the water or released from organic matter (like leaf litter) can lead to the deterioration of wetlands. No quantitative research has been conducted to determine the sources of the accumulated organic matter and nutrients in this system.
Rosh will find out whether the dominant sources of organic matter and nutrients come from outside the system, for example enter through river flows, or from inside the system, for example through the production of plant material (like algal blooms) and the breakdown of organic matter in the system. She will also see whether these sources change over time, or vary in different areas in the wetland. Previous research has shown that internally recycled organic matter and nutrients can sustain high levels of nutrients within a system, even when external sources have been appropriately managed. To trace the sources, Rosh will use biomarker methods (e.g. stable isotope analyses) which can be undertaken on larger organic material and nutrients dissolved within the water.
PhD Project 2: What’s for dinner?
Sian Glazier is constructing a quantitative and predictive ‘food web’ for the VWWS. Her PhD is a unique scientific study of bird diets in this system to help scientists, environmental managers and locals better understand the migratory water bird community.
She said not only would the food web help people better understand the main food sources and habitat that support the wetland’s key bird species but also the fish species that call the area home such as Black Bream and Sea Mullet.
Sian Glazier has completed the first year’s seasonal sampling with invertebrates, fish and birds sampled biannually in ‘wet’ (August/September) and ‘dry’ (February/March) seasons. Birds have been captured briefly to collect feathers and faeces and additional samples will be collected opportunistically from nesting sites and roosts. Feathers have been collected from apex predators in the system including sea eagles and ospreys providing a unique perspective to the food web.
“My fieldwork in December was very successful as I found a lot of feathers and poo on nests and roosts which will give us some clues to the birds’ diet.” Ms Glazier explained.
“In my first sampling in October I also caught very small juvenile goldfish in the upper Vasse Estuary. Given that these are freshwater species, it will be interesting to see what resources these invasive species are utilising and investigating their impact.”
Ms Glazier said she would examine dietary linkages from the smallest fauna (zooplankton) to the apex predators (Sea Eagles).
PhD Project 3: A question of value
Shivani Purushothaman is currently half way thought her study investigating the value of the Ramsar listed Vasse-Wonnerup wetland system to shed light on why the wetlands matter to the locals and wider community. She has completed her first stage of the research which were in-depth interviews and associated mapping of the values of the VWWS and will soon be circulating an online survey to better understand attitudes and perceptions about the wetland. She hopes the study will help inform its future management, as well as providing an analysis of the challenges and opportunities for the wetlands.
“The consultations aim to reveal what the local community values most about the wetlands, such as its environmental importance, agricultural land use, recreational opportunities or its aesthetic beauty,” said Ms Purushothaman.
“This is their opportunity to express what they hope for the future of the wetlands and to raise any concerns they may have. It will inject a human element into the scientific research projects also taking place at the wetlands.”
Ms Purushothaman said the dynamic bird life was a key aspect of the wetlands, drawing visitors to the area. However, her conversations so far had illustrated the importance of finding a balance between encouraging visitors and providing access to the wetlands without disrupting the birds and their habitat. This study will complement the consultation process undertaken through the Revitalising Geographe Waterways program by the Department of Water and GeoCatch under the Vasse Taskforce.
“Many of the people I’ve spoken to already know and love the wetlands very well and they are very happy this project is taking place. They have really opened up about the wetlands, but there are still many who need to get involved,” said Ms Purushothaman.
This project is supported by the South West Catchments Council, through funding from the Australian Government’s National Landcare Programme.