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Grovetown Lagoon Restoration Project

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Newsletter 50

Published on Feb 8, 2022

What's Living in the Lagoon?

eDNA testing

Although they have not always been appreciated by all people, wetlands are amazing places full of life and biodiversity. What is living in the Grovetown Lagoon? This is a question the Grovetown Lagoon whanau have been wondering and asking about over time. In order to know more of the species living in the Lagoon it was decided to do a trial of eDNA testing. Testing the DNA in the lagoon can show what plants and animals are living in and around the water. The samples cost $225 each. One sample was taken at each of the northern and southern outlets of the Lagoon. The sampling involved syringing water through a fine filter, then sending the preserved filter away to a laboratory for analysis. So what did the results show? The eDNA testing results were interesting, although not conclusive and there was one surprise find. It was hoped that the results may show a wide diversity of fish species and that the Lagoon has some rare secretive indigenous birds, such as the Australasian bittern. Also the plants were tested to show if there were any aquatic weed species that the group was unaware of.


 
The results showed that there are long and short fin eel, bullies, Inanga, Galaxiids and brown trout present. The bird species detected were unfortunately not very detailed showing ducks, swans and geese. The testing did not uncover any weeds which the group was unaware of. One unusual thing that the testing showed up was the presence of freshwater jellyfish. Freshwater jellyfish are small, (as large as a small coin), they feed on zooplankton and are harmless to humans and large animals. It was a complete surprise to find that there are freshwater jellyfish at the Lagoon. Department of Conservation staff recommended that we have more testing undertaken at different locations around the lagoon so who knows what future eDNA testing may uncover!
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