The complexities of managing water quality and ecology in the Vasse Estuary over summer were shared with the community at a science update hosted by GeoCatch.
Scientists from the Departments of Water and Environmental Regulation (DWER), Biodiversity, Conservation and Attractions (DBCA) and Edith Cowan University presented to 48 members of the community on proposed summer seawater inflows to the Vasse Estuary through the surge barrier, and the possible ecological impact preventions that are being taken into consideration.
Dr Linda Kalnejais from DWER gave an overview of the seawater inflow regimes that have been trialled since 2015 and the benefits and potential impacts of these to both water quality and ecology.
Linda explained that letting too much seawater into the estuary, or letting it in too early may have a negative impact on waterbirds or their food sources. Conversely, not letting seawater in or letting it in later in summer puts the estuary at risk of algal blooms and fish kills.
The balancing act that managers face was brought to the forefront by Kim Williams from DBCA, who explained to the group how Vasse Wonnerup waterbirds must be considered under various conventions, treaties and agreements both internationally and nationally. Kim gave an overview of DBCA’s waterbird monitoring results, seawater inflows to the Vasse Estuary and the changing distribution of waterbirds in summer.
GeoCatch Chair Felicity Bradshaw facilitated a Q&A session with the community and was pleased with the level of interest and understanding in the community.
“The community have high expectations of managers and I think listening to all of the science presented today, they now have a better understanding of the multiple variables managers are taking into account when making decisions about the wetlands”.
Evaluations from the event showed an improved community understanding of the science that informs management of the Vasse Wonnerup, and an improved confidence in waterway managers.
Dr Sora Marin-Estrella and Assoc Professor Chandra Salgado Kent from Edith Cowan University gave an overview of their investigations into the relationship between waterbird abundance and water regimes in the Vasse Wonnerup wetlands. They highlighted the importance of ongoing waterbird monitoring into the future, particularly timed around any seawater inflows to the Vasse Estuary.
The management options available for seawater inflow to the Vasse Estuary this summer will be discussed by the Vasse Wonnerup Wetlands Partnership later this month. The Vasse Wonnerup Wetlands Partnership is a multi-agency committee who oversee management of the wetlands.
“The Vasse Wonnerup Wetlands Partnership will weigh up the benefits and impacts of each management option, and ultimately make a decision on seawater inflow to the estuary this summer” said Felicity.
“We will give the community’s feedback from today to the decision-makers so it can be taken into account”.
Finding the right balance between water quality and ecology is an ongoing challenge. The community update, science and monitoring work is part of the Royalties for Region’s Healthy Estuaries WA and Revitalising Geographe Waterways programs. These State Government initiatives aim to support the long-term health of our south-west estuaries.