Thousands more dead and dying shellfish have been washed up on a beach on a stretch of coast where there has been a mass crustacean die-off.
The dead mussels, crabs, razor clams and starfish have been seen on the sands at Saltburn-by-the-Sea, south of the River Tees.
Stuart Marshall, who owns a nearby beach hut, said it was “devastating”
The Environment Agency (EA) said it was caused by the weather and high tides and was normal for the time of year.
But Mr Marshall, 58, said a large deposit of black debris had just arrived on the tide and was not normal.
“We do get bits of coal from time to time but not anything like this,” he said.
He also questioned rough seas had killed the creatures, saying the waters had been calm.
Helen Whitworth, from Northallerton, North Yorkshire, also said the black deposit was unexpected.
“This black area is not usually here – usually it’s a really beautiful beach,” she said.
Thousands of dead crustaceans washed up between Hartlepool and Whitby in 2021.
Fishermen have claimed the previous deaths were linked to the dredging of the River Tees but a panel of experts said a disease or parasite new to UK waters may have been responsible.
But the panel said it was “unable to identify a clear and convincing single cause for the unusual crustacean mortality”.
The EA said the recently arrived black substance was coal deposit “which is not unusual for this stretch of coastline”.
A spokesperson said: “While we know people are concerned, the combination of recent heavy swell, spring tides and onshore winds means natural wash ups will occur more often.”
Starfish, razor clams and mussels were easily dislodged during storms and some young fish were vulnerable to being stranded on shallow gradient beaches such as Saltburn, the EA added.
Follow BBC North East & Cumbria on Twitter, Facebook and Instagram. Send your story ideas to [email protected].