Study Links Crab Mortality to Dog Disease and Dredging | marine life

An independent study has linked the deaths of thousands of crabs and lobsters to a mysterious canine disease to the dredging of the River Tees, raising concerns for the government’s flagship freeport in Teesside – a key to the ‘levelling’ scheme post-Brexit from the Conservatives. .

The report has led local fishermen to reject a government theory that an ‘algal bloom’ is responsible for the huge piles of dead shellfish that have started washing up on beaches along the northeast coast of England in October.

A multi-agency investigation by the Department for Environment, Food and Rural Affairs (Defra) concluded on Friday that mass shellfish deaths, which the fishing industry says have threatened their livelihoods sustenance and raises fears of ecosystem collapse, “potentially result from naturally occurring harmful algal blooms”.

Algal blooms are a rapid growth of algae that can produce dangerous toxins in the water, sometimes marked by colored scum on the water. Scientists have warned they are becoming increasingly common and toxic around the world, and could be linked to the climate crisis.

Dog walkers on the beach at Saltburn-by-the-Sea in North Yorkshire. Photography: Christopher Thomond/The Guardian

Tim Deere-Jones, an independent marine pollution consultant and author of the report, said there was “no empirical evidence to support the theory that it has anything to do with an algal bloom”. Deere-Jones, who has 30 years’ experience of dredging issues as a consultant, said instead that data obtained through freedom of information requests from Defra and other agencies, linked mass mortalities to a specific chemical, pyridine, which can be released into the environment as a waste product from industrial processes.

“So far, the available evidence clearly indicates that pyridine is a potential cause of mortality,” he said. His analyzes point to several potential sources of pyridine release into the estuary, which could be decades old, but have sunk deep into the seafloor. “Based on the established fact that pyridine preferentially deposits in estuarine sediments, rather than remaining in the water column, it seems likely that the new deeper dredging being constructed has uncovered and redistributed sediments containing pyridine in the regional marine environment,” he added.

While Defra has stated that “all levels [of pyridine] detected in crab tissue are likely to be related to biological processes and not necessarily the environment,” Deere-Jones pointed out that control crab samples taken at Penzance contained just under 6 mg per kilogram of product. toxic chemical, Saltburn crabs were found to have over 400 mg per kg. “It’s not a natural level, it’s a human impact level,” he said.

Looking north across the Tees Estuary towards Seal Sands from South Gare.
Looking north across the Tees Estuary towards Seal Sands from South Gare. Photograph: Mark Pinder/The Guardian

Defra, which reviewed the satellite date showing an algal bloom along the coastal zone in late September 2021, dismissed this explanation, concluding that it is “unlikely that chemical pollution, sewage or infectious disease from aquatic animals were the cause of death”.

The agency also said there was no evidence linking recent reports of dead seals, the mysterious illness in dogs causing illness and diarrhea after walks along the coast in January, or the Hundreds of dead seabirds washed up in October.

However, the North East Fishing Collective, a group of commercial fishing associations, angling companies, conservationists and stakeholders along the northeast coast of England, have called the “total rubbish” explanation.

The group says they have all been “dramatically affected by recent events on the east coast. Our incomes have been reduced, our livelihoods threatened and our environments eroded.

Fishermen from Hartlepool to Scarborough say their catches of crabs and lobsters remain at 80% to 95% and dead crabs and lobsters were reported last week at Saltburn and Maske which they say has not probably not caused by an algal bloom in October.

Following a protest last November, the group set up crowdfunding and commissioned Deere-Jones to investigate. They have called for further investigations into the high levels of pyridine found in crabs and an immediate halt to dredging activities in the Tees, where they say a vessel ‘completed a year of dredging in 10 days’.

Commenting, Tees Valley Mayor Ben Houchen said: ‘No dredging of the River Tees has been carried out by Teesworks or the Teesside Freeport, the only dredging that has taken place is that carried out by PD Ports as statutory port authority.

“Like everyone in Teesside, Darlington and Hartlepool, I am concerned about the impact the death of so many crabs and lobsters has had on the livelihoods of people in Teesside and the North East Coast who depend on a healthy sea. The Tees and the North Sea play a huge role in our communities, and I hope we will see our sea life and coasts return to normal as soon as possible.

A spokesperson for the fishermen said algal blooms “do not occur naturally in our coastal waters in October. The temperatures are way too low” and demanded more evidence for the theory beyond satellite images.

A Defra spokesman said: “Our sampling established that no pyridine was present in the water or sediment samples we collected, but was detected in crab tissue from the affected areas and unaffected areas elsewhere in the country”.

The title and text of this article were modified on February 8 and 10. An earlier version said the independent study had linked crab mortality and dog sickness to the dredging of the Teesside Freeport; however, no dredging was carried out for this development.

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