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Mary Valley turtley awesome!

High fish diversity and the discovery of large turtles across three Mary Valley wetlands were the stand-out results from surveys conducted on Cape York late last year.

The work was carried out by Traditional Owners Jeanne Lyall, Fenice Yoren and Tracey Lowdown, of the Kyerrwanhdha Thingalkal Land Trust (Mary Valley station) with assistance and training from James Dobson from Cape York Natural Resource Management and Dr Brendan ‘Ebb’ Ebner from TropWATER, at James Cook University. 

“Fish diversity was very high despite surveying late dry season shallow pools that lacked any structure,” Ebb said. 

“And the number of large turtles in all the wetlands hasn’t been seen in surveys conducted elsewhere on the Cape. It was a great discovery.”

The surveys are part of the Building Traditional Owner Capacity to Maintain Water Quality on Traditional Lands Project. It involved water sampling and fish species monitoring in the culturally significant wetlands and river frontage of the Moorhead and Hahn rivers.

Three wetlands in Mary Valley have been found to have high fish and bird numbers, however, water quality results have fallen short, according to a new survey.

“The aim of the project is to increase Traditional Owner capacity to monitor water quality on eastern flowing Cape York catchments and gauge the impacts from cattle, mustering activities and weeds,” James said. 

“They will subsequently be able to conduct their own monitoring into the future to improve wetland habitat and water quality flowing into the Great Barrier Reef.”

Before the fish and water survey began, the Project involved erecting a cattle exclusion fence to protect the wetlands and riparian areas of the Moorhead River. Herbicides and ACDC training and certification was also provided so areas badly affected by weeds could be sprayed. 

“The survey data will give us a baseline so hopefully we see more improvement in wetland condition in follow up surveys now that the cattle have been excluded,” James said.

The Traditional Owners team learned how to conduct basic wetland health assessment techniques including:

  • setting up survey nets and counting, measuring and recording fish species;
  • conducting a scoring method for assessing wetland health, based on parameters that included impact from cattle, human infrastructure, fire, weeds and positive impacts such as biodiversity, fringing vegetation and aquatic vegetation;
  • using a probe to assess water quality; and
  • collecting water samples to be sent for analysis.

“There was no doubt we all worked well together as a team and Jeanne, Tracey and Fenice, I know, had a blast,” James said. 

Overall wetland results were:

  • Wetland A 67% (good),
  • Wetland B 74% (good)
  • Wetland C 64% (medium)

As well as good bird numbers and diversity and high fish numbers, each wetland supported Northern long-necked turtles. Wetland A also supported juvenile freshwater crocodiles and multiple species of freshwater turtle. Wetland C was high in fish numbers but low in species diversity.

Water quality for each wetland showed very high turbidity with lots of fine sediment and above-safe levels of lead. Wetland C also had above safe levels of manganese and arsenic. 

“These high levels of elements are typical of dry season pools where refuse from cattle and aggregating birds have accumulated and will likely be restored to healthy levels after a wet season flush,” James said.

On land, there was high pig and cattle damage, and Wetland A was infested with sickle pod.

The good news was the connectivity of the three wetlands - they were close to other wetlands and rivers, there was  little human disturbance and they had healthy fringing vegetation.

The Project is funded by the partnership between the Australian Government's Reef Trust and the Great Barrier Reef Foundation.


Assessment methods followed the Bolton, K.G.E. (2001) North Coast Wetland Assessment Guide
Manual. Department of Land and Water Conservation and Southern Cross University. ISBN 0 7347 5232 6#

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