Jellyfish sightings around Ireland's coast are at their highest level in 25 years.
The latest figures from the Coastwatch survey for the island of Ireland revealed that jellyfish were more common and found in more areas than ever before in the 25-year history of the survey.
Coastwatch reported some "worrying findings" in the snapshot survey carried out this autumn, including an unusual bloom of small brown jellyfish that devastated any wildlife they encountered, the discovery of a 5.1ft diameter barrel jellyfish off the west coast, and a sighting of a trigger fish in Lough Foyle, the furthest north this Mediterranean species has been seen.
"What this says to us is that our waters are warming," Coastwatch International co-ordinator Karin Dubsky said.
"One of the worrying ones was that there were a lot of the small brown jellyfish, which do a lot of damage to wildlife. They were appearing late in the year and in massive quantities.
"It's a worrying development because if we are going to increase aquaculture we might be facing much bigger losses and much higher risks than before.
"The largest jellyfish we found was on the west coast and was 5.1ft in diameter – it was absolutely enormous."
Coastwatch said nature appears to have been responding to the abnormally hot summer, which has driven sea temperatures up – the type of weather conditions and sea temperature changes predicted with climate change.
"Nobody had seen a trigger fish as far north and as late in the year before – this is a Mediterranean species," Karin said.
The interim survey results were based on reports from around 900 volunteers and found that landfill materials were found at a fifth of sites surveyed. Some old coastal landfill sites were eroding and releasing old waste materials.
Monica McCard of Queen's University Belfast, who covered Northern Ireland, said there was far more pollution than expected. Meanwhile, the invasive cordgrass was found at a number of mudflat sites in the north west, posing concerns over the threat to brent-geese feeding grounds.