London’s River Thames, now home to sharks, seals and sea horses, is no longer ‘biologically dead’


Some 60 years ago, parts of the River Thames were declared biologically dead. But the famous waterway that cuts through London has been revived and is now home to hundreds of wildlife species, such as sea horses and sharks.


The latest State of the Thames report, released by the Zoological Society of London on Wednesday, found that cleanup efforts over recent decades have brought down levels of chemicals such as phosphorus and conserved salt marshes for birds and fish, making the river “home to myriad wildlife as diverse as London itself.”

The report also highlighted many challenges the Thames faces, including rising water temperatures and sea levels due to climate change. For instance, summer temperatures in parts of the river have increased an average of 0.19 degrees Celsius (0.34 degrees Fahrenheit) each year since 2007, researchers found. Even slight alterations in seasonal heat may upset the river’s ecosystem and erode living habitats.


The researchers also found elevated nitrate concentration that threatens water quality. Much of London’s drinking water comes from the river.

Among modern cities, the Thames hasn’t always been a model for successful environmental protection. It became heavily polluted during the Industrial Revolution as toxic runoffs from tanneries and human waste found their way to the river. The “Great Stink” of 1858, caused in part by human sewage flowing into the Thames, forced the British Parliament to build better wastewater disposal systems.

But even in 1959, oxygen levels in the Thames had dropped so low that the British Natural History Museum declared it biologically incapable of sustaining marine life. At around this time, authorities began investing in better sewage treatment facilities and better monitoring key environmental indicators, sparking a turnaround.


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The Washington Post, 12 November 2021