Wetlands Australia 32: Connected wetlands built in agricultural landscape provide habitat for fish

Author: Dr Nathan Waltham, James Cook University

A project in the catchments of the Great Barrier Reef is assessing the environmental benefits of agricultural land conversion to wetlands, by surveying already constructed land to wetland conversion sites.

Coastal wetlands in the catchments of the Great Barrier Reef (GBR) provide extensive environmental, cultural and economic value. These wetlands play a role in protecting our coastline, buffering against wet season flood waters, improving water quality and maintaining fisheries productivity. Despite these values, many wetlands have been modified or impacted because of land use change (such as agricultural, aquaculture, peri-urban/urban, and industrial expansion). These wetlands no longer function properly and have lost their original value as habitat for native plants, fish, birds and other animals; reduced capacity for carbon sequestration; and reduced flood storage capacity.

A recent review publication outlined that restoring cultural, biodiversity and water quality values to coastal wetlands has become a priority in the Great Barrier Reef catchments, and will assist government reach targets set in the Reef 2050 Plan. The Queensland Government has also developed a Wetlands in the Great Barrier Reef Catchments (Management Strategy 2016-2021) which sets out a framework for delivering successful restoration projects in the GBR that is supported by agreed values and processes.

Left: Wetlands constructed on floodplains in 1990's. Photo: Ross Digman. Right: Same wetland 2019. Photo: Dr Nathan Waltham.

A recent survey of wetlands on the Tully floodplain from the last 25 years revealed many fish species utilise these wetlands, including species that have a diadromous ecology, meaning they require access to both freshwater and saltwater to complete lifecycle stages. This research is funded through the Australian Government’s National Environment Science Program Tropical Water Quality Hub.

Barramundi caught in Tully lagoon (54cm). Photo: Dr Nathan Waltham.

The results of this study will inform future wetland construction design over low-lying coastal areas in the GBR catchment, and in doing so, maximise the water quality and ecosystem services return for funding invested in wetland projects. The final report is due December 2020.

Further information

Contact Dr Nathan Waltham at Nathan.waltham@jcu.edu.au

NESP project: Evaluating the costs and benefits of agricultural land conversion to wetlands