Scientists and traditional owners are restoring oyster reefs once common along the muddy banks of the Russell and Mulgrave Rivers in Far North Queensland.<\/p>\n
The river, 50 kilometres south of Cairns, is home to the first tropical oyster reef restoration project in northern Australia.<\/p>\n
Led by Indigenous-owned Jaragun Ecoservices in partnership with James Cook University, the pilot project aims to protect mangroves, improve water quality, and support marine life, while researchers assess the shellfish reefs’ ecological importance.<\/p>\n
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Liz Owen believes restoring oyster reefs in the river catchments will help the Great Barrier Reef. (ABC Far North: Brendan Mounter)<\/p>\n
Jaragun CEO Liz Owen said the Russell and Mulgrave rivers had experienced years of environmental pressure, with mangrove-covered riverbanks eroding over years.<\/p>\n
After Cyclone Jasper, damaged mangroves released mud and sediment<\/a>, choking marine habitats and slowing coral reef recovery.<\/p>\n “Oyster reefs used to protect the mangrove system in particular from erosion,” Ms Owen said.<\/p>\n “They also provide significant water quality improvement and habitat for marine life.”<\/p>\n She said mangrove forests stabilised shorelines, filtered sediment, and protected seagrass and coral from pollution.<\/p>\n Sections of bank along the Russell River catchment are washed away by erosion. (ABC Far North: Brendan Mounter)<\/p>\n In the wild, oysters attach to shells or hard surfaces, slowly forming layered reefs over time.<\/p>\n Juvenile oysters, or spat, settle on the shells, creating dense clusters that stabilise sediments and provide habitat.<\/p>\n The Russell River project mimics the process by placing live oysters and empty shells in Robust Oyster Baskets (ROBs) on the riverbed.\u00a0<\/p>\n Robust Oyster Baskets help the oysters to clump together. (ABC Far North: Brendan Mounter)<\/p>\n How the oyster reefs work<\/p>\n James Cook University researcher Nathan Waltham said oysters were “really important” to tropical coastal ecosystems, but historically undervalued.<\/p>\n Researchers say more oysters are growing naturally in the Russell River catchment. (ABC Far North: Brendan Mounter)<\/p>\n “A single oyster can filter between 10 litres and almost 100 litres of water a day,” Dr Waltham said.<\/p>\n “So collectively they filter large volumes, removing nutrients, heavy metals, pesticides and herbicides before it reaches the Great Barrier Reef.”<\/p>\n Dr Waltham said the pilot project was monitoring water salinity, temperature, fish populations and chemical levels to track how oysters improved water quality.<\/p>\n Nathan Waltham tests water quality near where a Robust Oyster Basket has been placed. (ABC Far North: Brendan Mounter)<\/p>\n “The next few months will be crucial as they start to reproduce and colonise the ROBs,” he said.<\/p>\n The protective cages have sheltered the oysters from predators and strong currents, while allowing them to layer, grow, and eventually form self-sustaining reefs.<\/p>\n Why grow oyster reefs?<\/p>\n Globally, more than 90 per cent of oyster reefs have been lost, and reefs in southern Australian states are critically endangered<\/a>.<\/p>\n<\/p>\n
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