Our directory of things of interest

University Directory

Back from the dead

Back from the dead
16 Jan
2016
Declared biologically dead in 1950s, the Thames is now home to hundreds of species of fish, seals, porpoises and more

According to a ten-year marine mammal survey by the Zoological Society of London, there have been more than 1,000 harbour seal sightings along the river Thames over the past decade, along with dozens of harbour porpoise sightings and even the occasional whale. ‘People look at the Thames and see murky water,’ says Sofia Castello y Tickell, co-author of the study, ‘but in fact, it is full of life ranging from invertebrates to fish and top predators such as seals.’

Harbour seals have been seen at Hampton Court, porpoises and dolphins at Teddington Lock and whales as far as Gravesend

The tidal Thames had been used as the London’s drainage system for centuries before it was declared biologically dead by the Natural History Museum in 1957. The waters around the most developed areas of the city had become anaerobic – devoid of oxygen and unable to sustain life. Following the introduction of tough legislation in the 1990s, the ‘big stink’ began to make a biological comeback. Most harmful effluents are now prevented from entering the Thames and its tributaries, while sewage is treated and exported elsewhere. Given this chance, 400 invertebrates and 125 species of fish, have returned to the grey-green waters. ‘Marine mammals are most likely following their food,’ says Joanne Barker, marine biologist at the ZSL and co-author of the study. ‘Harbour seals have been seen at Hampton Court, porpoises and dolphins at Teddington Lock and whales as far as Gravesend.’ Canary Wharf is the best place to see marine species as more sightings were reported there than anywhere else along the Thames estuary.

While the water quality has improved, harmful pollutants are still adrift in the form of plastics. A study by Royal Holloway found 70 per cent of flounder had plastic in their guts. Plastics are thought to cause the bioaccumulation of toxins in marine species. ‘Although much cleaner than in the 1950’s,’ says Barker, ‘the Thames still has a number of problems and has a long way to go before I would describe it as being clean.’

This article was published in the January 2016 edition of Geographical magazine.

Related items

Geographical Week

Get the best of Geographical delivered straight to your inbox every Friday.

Subscribe to Geographical!

Adventure Canada

EDUCATION PARTNERS

Aberystwyth University University of Greenwich The University of Winchester

TRAVEL PARTNERS

Ponant

Silversea

Travel the Unknown

DOSSIERS

Like longer reads? Try our in-depth dossiers that provide a comprehensive view of each topic

  • National Clean Air Day
    For National Clean Air Day, Geographical brings together stories about air pollution and the kind of solutions needed to tackle it ...
    The green dragon awakens
    China has achieved remarkable economic success following the principle of developing first and cleaning up later. But now the country with the world's...
    The true cost of meat
    As one of the world’s biggest methane emitters, the meat industry has a lot more to concern itself with than merely dietary issues ...
    Hung out to dry
    Wetlands are vital storehouses of biodiversity and important bulwarks against the effects of climate change, while also providing livelihoods for mill...
    Mexico City: boom town
    Twenty years ago, Mexico City was considered the ultimate urban disaster. But, recent political and economic reforms have transformed it into a hub of...

MORE DOSSIERS

NEVER MISS A STORY - Follow Geographical on Social

Want to stay up to date with breaking Geographical stories? Join the thousands following us on Twitter, Facebook and Instagram and stay informed about the world.

More articles in PLACES...

Mapping

Benjamin Hennig charts the growth and impact of the world’s…

Deserts

Long-term studies reveal the Sahara desert has expanded substantially over…

Water

South America’s wealthiest economy is at a crossroads between environmental…

Forests

The European Court of Justice finds the logging of a…

Mountains

In this extract from his new book, Tides, mountain climber…

Cities

New data from the World Health Organization reveals that nine…

Water

In the wake of the water crisis in Flint, Michigan,…

Mapping

Benjamin Hennig maps out the global production and distribution levels…

Water

Millions of Americans are living in areas at high-risk of…

Mapping

New interactive maps combine precipitation and temperature to show climate…

Cities

Public transport in India could be on the verge of…

Water

To retrace the route of the fur voyageurs on the waterways…

Cities

IPCC Cities and Climate Change Conference: Alberta host dresses non-renewable…

Water

Increased carbon dioxide is affecting freshwater ecosystems

Forests

The latest laser scanning technology reveals new insights into the…

Forests

Deforestation is having an unexpected effect in the Amazon: fewer…

Forests

The iconic Douglas fir tree, familiar to fans of the…

Forests

Rocky Mountain forests are not regenerating after wildfires

Cities

Cape Town is edging closer to ‘Day Zero’, the long-feared…

Water

Ongoing restoration projects are breathing new life into Florida’s Everglades