Article Index

Ecological health

Measures of ecological health complement water quality monitoring and reporting and provide more information about the overall health of the waterway.

The Department of Biodiversity, Conservation and Attractions (DBCA) has worked with project partners at Murdoch University and DWER to develop approaches to monitor fish and seagrass communities as indicators of ecosystem health.

Monitoring and evaluating fish communities

DBCA continues to partner with Murdoch University to annually sample and report on fish communities as an indicator of the condition of the Swan Canning Estuary, with contractual arrangements extending until 2021.

Murdoch University developed the Fish Community Index over five years (2007-12) in collaboration with the State Government. The index uses a suite of fish metrics, including diversity and the number of species, to characterise the fish community and its response to estuarine condition. The index does not focus on individual populations or measure biological performance or health of any individual fish species.

The primary purpose of the Fish Community Index is to provide an ecological indicator of estuarine condition that complements existing water quality monitoring and evaluation. The index is applied annually as part of an on-going monitoring and reporting framework.

Fish communities have been monitored in summer and autumn at six nearshore and six offshore sites in the upper, middle and lower Swan, as well as in the lower Canning, since 2012.

The latest (2020) report is available for download at the bottom of this page, along with earlier reports. Data for the 2021 report is current being compiled.

Seagrass health and distribution

Seagrasses are some of the most productive organisms in the world with productivity rates that can be twice that of forests. They play a role in maintaining oxygen levels at the sediment/water interface, support diverse and productive faunal assemblages and are an important food source for animals such as WA’s iconic black swan.

In the Swan Canning Riverpark there are three main species of seagrass, with paddleweed (Halophila ovalis) being the dominant species.

DBCA has worked with DWER to develop a robust and easily repeatable method of surveying seagrass species composition and percentage coverage at sites in the lower Swan and Canning estuaries. This is coupled with monitoring of seagrass response to environmental pressures. Insights into seagrass health and distribution provided by this monitoring and evaluation program provide a useful complement to existing water quality reporting and will allow management policies to be specifically targeted at improving the resilience of seagrass in the Swan Canning Estuary.

Two reports have been released describing the projects and their results to-date.