Thousands of new species discovered in Guernsey’s freshwater habitats

Monday, 14 September 2026 07:05

Scientists say the results of Guernsey's first island-wide environmental DNA survey are "nothing short of incredible."

Guernsey Water and the Nature Commission have been testing water for DNA left behind by organisms.

Samples were taken from 26 locations, including 15 streams, 9 ponds and 2 brackish water habitats.

2,630 different organisms were detected, with 2,249 not previously recorded in Guernsey.

The DNA found included European eels, brown rats and American signal crayfish.

Newts were found more often in streams, while frogs were more common in ponds.

The Vrangue stream had the most life with 748 detections, while Pulias pond had the lowest, with 196.

Water Quality Scientist Tim Harris says the results have exceeded his expectations.

“This is nothing short of incredible and provides the most accurate record of what’s in local waters ever undertaken.

"The results have blown us away, and frankly we can’t quite believe what they’ve told us.

"To have more than 2,000 new detections that no one knew about represents a step-change in our understanding of just what’s on Guernsey.

"We’re performing a second set of samples soon to make sure all the findings can be confirmed.

"But to say I am astounded would be an understatement.”

The survey results will also be used to monitor change, influence conservation activity, and identify potential water-quality risks.

Nature Commission Ecologist Charlotte Burgoine says it's an exciting project.

“It’s been great to work with Guernsey Water to understand more about our freshwater species with eDNA sampling.

"We certainly have a lot more freshwater data after the first sampling round! It will be good to complete the second sampling round, see if anything different pops up, and then analyse the results.

"We can include the results in our next State of Nature report and contribute records to the biological database, filling a big data gap.”

Comments