A major effort to remove invasive rice grass from Tasmania’s Duck Bay is showing major signs of recovery, with native vegetation returning and the number of fish species rising from five to 11.
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number → remove → 11
The changes came within just two to three years of the weed being removed from parts of the wetland.
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weed → come → wetland
The restoration work is being carried out by Circular Head Landcare, which has spent almost 15 years trying to eradicate rice grass from Tasmania’s largest coastal wetlands, according to ABC news.
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which → carry → news
The group, with support from farmers, has reduced the weed from about 50 hectares to just five hectares.
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group → reduce → hectares
Scientists from Univrersity of Tasmania
studying the wetland also found that fish were not only returning but were using the restored saltmarsh areas for feeding.
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fish → study → feeding
Among the species benefiting are yellow-eye mullet, which are caught both commercially and recreationally, and hardyheads, a small bait fish eaten by larger species.
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which → benefit → species
The restoration has required a large effort on land and in the water.
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restoration → require → water
Rice grass has been treated with the herbicide Fusilade Forte using quadbikes, vehicles with long hoses and, more recently, drones.
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grass → treat → hoses
Volunteers also search the coastline for seedlings that may have been missed or have grown again.
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that → search → seedlings
How rice grass spread across wetland
Rice grass was first planted in the 1940s to beautify Smithton’s Duck River.
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grass → spread → River
Over the years, it spread across mudflats and saltmarsh along a 120-kilometre stretch from Woolnorth to Stanley.
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it → spread → Stanley
The weed can form dense growth that takes over areas used by native plants and animals.
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that → form → plants
Sue Jennings, a volunteer with Circular Head Landcare, says the grass became increasingly dense when left untreated.
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grass → say → Landcare
It just gets thicker and thicker," Jennings said.
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Jennings → get → ?
Duck Bay is part of Tasmania’s largest coastal wetland system, which includes sheltered bays, estuaries and tidal islands.
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which → include → bays
The area is also important for shorebirds, with thousands visiting Tasmania’s far north-west during summer.
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thousands → visit → summer
Some of these birds travel long distances to reach the wetland.
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Some → travel → wetland
They include the far eastern curlew, ruddy turnstone and red-necked stint.
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They → include → curlew
The small red-necked stint weighs only about 30 to 35 grams.
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stint → weigh → grams
Shorebird ecologist Eric Woehler says red-necked stints can travel enormous distances during their lives.
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stints → say → lives
"Over 20 years, red-necked stints would fly half a million kilometres, which is farther than the distance between the earth and the moon," Woehler said.
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Woehler → fly → earth
The wetland also supports fish including gobies, sardines, flounder, galaxiids, garfish, leatherjackets and Australian salmon.
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wetland → support → gobies
Rice grass was treated with herbicide using quadbikes, vehicles with long hoses and drones.
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grass → treat → hoses
Native saltmarsh plants return
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plants → return → ?
Removing rice grass has allowed native saltmarsh vegetation to recover.
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vegetation → remove → grass
Jennings says the herbicide being used kills pasture grass and rice grass but does not kill the saltmarsh plants.
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herbicide → say → plants
"It kills pasture grass and it kills rice grass, but it doesn't kill the salt marsh plants.
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it → kill → plants
So as we get rid of the rice grass, the salt marsh plants start to recover on their own," she says.
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she → rid → own
During mass herbicide spraying, harvesting is stopped for an additional seven days as a safety measure.
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harvesting → stop → measure
According to Tasmanian Oyster Company chair Jon Poke, the pause can mean a significant financial loss for the business.
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pause → accord → business
The company can harvest up to 18,000 to 20,000 dozen oysters a week, meaning the two-week suspension could represent a lost opportunity of nearly half a million dollars in sales.
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suspension → harvest → sales
However, Poke says protecting the wetland was important for the long-term survival of the farms.
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protecting → say → farms
"We looked at what had happened in other estuaries, and for my own business to survive, we needed to make sure that the environment was looked after.
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environment → look → estuaries
Eventually rice grass would have closed our farms down," he says.
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he → close → farms
Fish return after rice grass removal
University of Tasmania scientists have been tracking changes in native saltmarsh vegetation and fish communities as the restoration continues.
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restoration → return → vegetation
Wetland ecologist Vishnu Prahalad says the recovery had happened faster than expected in some areas.
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recovery → say → areas
"After two years, three years, you wouldn't even be able to say there was rice grass there, so all the native vegetation has come back," Prahalad said.
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Prahalad → say → years
The number of fish species recorded in the restored areas increased from five to 11.
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number → record → 11
Scientists also saw a major change in the number of fish caught during their surveys.
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Scientists → see → surveys
In the first year, researchers struggled to find fish, catching only two across four nets.
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researchers → struggle → nets
…and 10 more, not listed.
The Aporia
