eDNA Water Sampling Project

In 2021 an ambitious project was undertaken in the river Suir to evaluate the status of 3 endangered species that historically inhabited the river.

White clawed Crayfish, Freshwater Pearl Mussels & Sea Lamprey

Distribution of these species is not well known. While traditional methods can assist in assessing the distribution, these methods are invasive and sometimes lethal as they rely on catching and handling individual specimens. For this reason, this project focussed on using environmental DNA analysis, a method recently developed that does not rely on capturing individual specimen and is non-invasive.

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What is eDNA?

Environmental DNA (eDNA) relies on DNA  genetic material that is released naturally into the aquatic environment such as cells found in fecal matter, slime, and gametes etc. 

This DNA will be found in water

By sampling and filtering water, eDNA can be isolated that are unique to the target species.

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White clawed crayfish 

IUCN Conservation Status: Endangered

Crayfish are freshwater relatives of the marine lobsters which they resemble closely. It is an important species ecologically both as a grazer of plants and as a favoured food item of the Otter.

Has its last stronghold in Ireland and has lately been devastated by the invasive crayfish plague. 

‍https://species.biodiversityireland.ie/profile.php?taxonId=17487&taxonName=crayfish

https://www.npws.ie/research-projects/animal-species/invertebrates/white-clawed-crayfish-austropotamobius-pallipes

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Freshwater pearl mussel

IUCN Conservation Status: Critically Endangered

Freshwater pearl mussels live in fast-flowing freshwater. They’re very particular about their habitats, as the juveniles cannot survive in poor quality water.

Freshwater pearl mussels, like the saltwater mussels we eat, are bivalves. Bivalves are molluscs with soft bodies protected by a hinged shell which can open and close as they need. They have one strong ‘foot’ which they use to burrow into gravel and sand, and a long tubelike siphon which they use to filter feed. Freshwater pearl mussels display reduced senescence, or reduced aging. They can live to be 140, making them the longest-lived animals in Ireland

https://iwt.ie/species-in-focus-freshwater-pearl-mussels/

https://species.biodiversityireland.ie/profile.php?taxonId=123483

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Sea Lamprey

IUCN Conservation Status: Near threatened

Migrating to sea as juveniles and returning as adults to breed in freshwater.

Like all lampreys, sea lamprey lack gill covers or paired fins and have an oral sucker disc instead of a mouth with jaws.

https://species.biodiversityireland.ie/profile.php?taxonId=108636

https://www.fisheriesireland.ie/species/sea-lamprey-petromyzon-marinus#:~:text=The%20sea%20lamprey%20is%20native,of%20a%20mouth%20with%20jaws

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SuirCan with significant assistance from various organisations organised &  trained 43 citizen scientists to take water samples at 120 different sites, which were then supplied to BioID Lab in UCD for analysis to assess for the presence of the three target species.  

Note that locations where no eDNA from the target species could be detected can still support them, but concentrations were too low for detection.

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Results

• White clawed crayfish can still be found in some tributaries of the River Suir and these precious survivors are in need of preservation and protection. 
• The range of the highly threatened freshwater pearl mussel has diminished drastically but eDNA results indicate that they can still be found in some tributaries.
• It is also clear from the eDNA results that sea lamprey can ascend the River Suir, and that the fish passage at the weir at Clonmel allows for upstream migration. 

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A summary of the project can be downloaded here.

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A more detailed presentation of the results can be downloaded here.

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Should any organistion which to discuss results further please E-mail suircanclonmel@gmail.com

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