In the 1830s and 40s, the Thames was declared as ‘biologically dead’. It is now considered to be the cleanest river running through a major city, and was described as having a ‘thriving ecosystem’ as of 2012.
Initially, the Thames was polluted in Victorian times by poor sewer systems leading directly into the river. This worsened during the World Wars, as the existing sewers were damaged by bombing. Industrial pollution along the river away from the cities has also been a long-term issue for the river environment. It depleted oxygen supplies in the water, making it almost impossible for many organisms to survive. In the 1960s, laws were enforced to prevent the flow of polluted water into the river. Some problems have been caused by flood defense strategies, such as the high concrete banks in central London, which have increased the flow rate, making it difficult for fish to swim in. More recently, the main issue has become the dumping of plastics in the river, especially carrier bags. A survey found small amounts of plastic in the stomachs of 75% of the river’s marine life.
"Recent years have seen the return of porpoises, dolphins, over 120 species of fish, and even the occasional whale"
The Cleaner Thames scheme was launched in September 2015 in an attempt to combat the deposition of plastic waste in the river, encouraging volunteers to pick rubbish from the river for recycling. Improvement in conditions of the river may have also been influenced by the general decline of industry in the UK, although there are still numerous industrial sites scattered along the river bank towards the estuary. Unfortunately, Boris Johnson has recently suggested the construction of an airport on an island in the Thames estuary, which would definitely not help in reducing the levels of pollution in the area. On a more positive note, other potentially more sustainable plans have been produced to further the regeneration of the Thames and its surrounding areas, hoping to return the river to its natural, pre-industrial state.
The input from a number of environmental and sustainability schemes has vastly improved the state of the Thames. Recent years have seen the return of porpoises, dolphins, over 120 species of fish, and even the occasional whale. Even though much of the river remains murky and grey, seals can often be spotted in the Thames estuary and along the docks at Billingsgate. Regulations now apply to the river and its ecosystems, which will continue to improve the Thames and its surrounding areas.
In our short time on the planet Earth we have managed to do a lot of harm. We have destroyed and polluted habitats, caused species extinction, and hurt other human beings as well as the environment. One of the many species that has suffered from our behaviour are wild horses. Now, we’re not talking about the Wild American West and its mustangs, but rather the Wild East and the grasslands of Mongolia. That is where the only truly wild horse, the Przewalski’s horse, roams. These horses were nearly driven to extinction but are now slowly making a recovery, both thanks to human interference.
Unlike mustangs that originate from domesticated horses gone feral, the Przewalski’s horse has never been tamed and therefore are the world’s only true “wild horses”. Some scientists also argue that they should be described as a separate species, as their genes that control metabolism, reproduction and general behaviour differ from domesticated horses. Przewalski’s horses also look slightly different compared to most horse breeds. They are shorter, only about 4ft tall, and have a short mane that stands upright, much like the mane of zebras. And while domestic horses have 64 chromosomes, Przewalski’s horses have 66.
These horses have been around since prehistoric times, but were only scientifically discovered in the 19th century by a Russian explorer Nikolai Przewalski (you can probably guess where they got their name from). However, the last Przewalski’s horses living in freedom disappeared by the 1970’s due to hunting, land use and harsh Mongolian winters. Although they were now extinct in the wild, there were a few Przewalski’s horses living in zoos. Thanks to an extensive breeding programme their number has since increased from 12 up to 1500. Once the species was no longer in immediate danger, scientists turned their focus towards returning it to freedom. There are now around 400 horses in the reintroduction sites in Mongolia and China, where the horses live in the wild with indirect human assistance.
“Unlike mustangs that originate from domesticated horses gone feral, the Przewalski’s horse has never been tamed”
There are still threats to the full survival of the species, such as crossbreeding with domestic horses and, on the other hand, lack of genetic diversity and inbreeding. However, scientists are optimistic and the breeding programme has been so successful that the Przewalski’s horse is no longer classified as ‘extinct in the wild’ but ‘critically endangered’, which is a huge achievement on the road to recovery.