2025 'year of the octopus', as numbers spike in the South West
Warm conditions have led to the biggest bloom in numbers for 75 years
It has been the "year of the octopus" in seas off the south west of England, as warm conditions led to the biggest bloom in numbers for 75 years.
Divers and snorkellers reported numerous sightings, including of multiple octopuses, with the "alien" animals witnessed walking, mating and even grabbing at an underwater camera, while fishers were finding them in crab and lobster pots and when trawling, conservationists said.
But elsewhere UK coastal and marine wildlife have been hit by pollution spills, destructive fishing and ocean heatwaves, with climate change driving new and invasive species into the seas around the country.
In their annual review of the year, the Wildlife Trusts have charted the highs and lows for wildlife and habitats around the UK's coasts in 2025.
The trusts said 2025 was bookended by environmental disasters, with a collision between an oil tanker and a container ship in the North Sea in March spilling huge quantities of plastic resin pellets, and nearly 4.5 tonnes of bio-beads released from a water treatment plant in Sussex in November.
Following the North Sea collision, nearly 19 tonnes of burned "nurdles" or plastic pellets were cleared from Lincolnshire beaches, while there was significant plastic pollution at Holme Dunes and Cley Marshes in Norfolk.
Millions of bio-beads, which are used in water treatment processes and are easily ingested by marine animals and potentially carcinogenic due to the hydrocarbons and heavy metals that attach to them, have polluted Camber Sands and Rye Harbour nature reserve.
Sussex Wildlife Trust is battling to remove them from precious saltmarshes at the nature reserve, a protected site that is notable for 80 species of birds.
But it was better news for wildlife elsewhere, with a record 46,000 puffins recorded on Skomer, Pembrokeshire, by the Wildlife Trusts of South and West Wales, while the charismatic bird has made a comeback on the Isle of Muck following conservation efforts by Ulster Wildlife Trust to remove invasive brown rats.
Two puffins were caught on camera coming out of a burrow on the island off the Antrim coast, a positive sign they are breeding, conservationists said.
And, in the south west, there was an explosion in the number of common or Mediterranean octopus which is at its most northerly range in the English Channel, and is normally rarely seen in British waters.
Matt Slater, marine conservation officer at Cornwall Wildlife Trust, said the mild winter in 2025 helped lead to "an exceptional octopus population explosion, the like of which hasn't been seen in our waters for 75 years".
While their presence caused concern for fishers whose lobster, crab and scallop catches were being preyed on by the octopuses, they rapidly developed markets for selling them from Cornish ports across the world, he said.
The octopus lives for just two years but can grow to 1.5 metres across and weigh six to eight kilogrammes.
Mr Slater told the Press Association: "They are quite an incredible thing to witness, they're such fascinating animals and so alien and intriguing to people."
From historical evidence, the blooms only seem to last a couple of years, so there could still be octopuses around next year, he said.
But with warming seas and milder winters due to climate change, these events could increase in frequency.
"With warming seas we're finding that warmer water species tend to be moving north, so it's possible that we might be seeing their range spreading further and further north and these blooms increasing," he said.
Other species are on the move with climate change, with the UK seas hit by a significant marine heatwave during the summer.
Many of these are invasive non-native species that could affect local wildlife, including Pacific oysters recorded on Alderney, and red ripple bryozoan which lives in large encrusting colonies that can impact surrounding habitats.
Sea slug species arriving from warmer waters, the first volcano barnacles in North Wales and the dominance of Montagu's crabs in South Devon and Cornwall all show how climate change is affecting wildlife.
Wildlife sightings this year also include a critically endangered angelshark and sunfish spotted off the east coast, while a record number of grey seals were counted at South Walney nature reserve near Barrow by Cumbria Wildlife Trust.
Wildlife Trusts around the country have been taking action to support wildlife, and improve resilience to the rising seas and worsening storm damage brought by climate change.
This incudes returning 300,000 native oysters to the Humber Estuary and restoring seagrass in Essex, Hampshire and Durham.
The charities predict there will be more octopus and climate indicator species in UK waters next year, while warming seas mean cod and haddock now only found in northern parts of the UK and anchovies, sardines, and garfish - which are prey for blue fin tuna - in the south west.
And they are calling for an end to bottom trawling, a destructive fishing practice which damages seafloor habitats as heavy gear is pulled over them.
Ruth Williams, head of marine at the Wildlife Trusts, said: "In 2025 we've recorded mussel beds forming off the Sussex coast in an area previously decimated by bottom trawling.
"Now the Government needs to ban this horrific practice from all Marine Protected Areas."