Thames is no longer a dead place: there are sharks and seals again. In 1957, the river was declared “biologically dead”

    24 Nov 2021

    Specialists of the Zoological Society of London (ZSL) have been monitoring the ecology of the Thames and its estuary for many years. In 1957, the river was declared “biologically dead”, but already in the 1990s, the situation began to improve, National Geographic states.

    In the early 2000s, the Thames Marine Mammal Sightings Survey (TMMSS) program was launched, in which scientists asked everyone to send their testimonies of encounters with representatives of the fauna.

    Almost 1,500 people provided data; the main observation area is the Canary Wharf business district, and seals are most often seen here. ZSL biologists explain such statistics by the fact that a large concentration of people in this part of London naturally gives more results, and seals are easier to see than any fish.

    Summarizing all the information, ZSL reports that the Thames is now home to such species of sharks as soup (Galeorhinus galeus), star weasel (Mustelus asterias) and katran (Squalus), as well as 92 species of birds and 115 species of fish, including sea pipit, European smelt and river eel.

    Among marine mammals, there are long-nosed (Halichoerus grypus) and common (Phoca vitulina) seals, as well as porpoises (Phocoena phocoena). But if the last of the named animals is still rare, then seals on the Thames are already forming entire colonies, numbering many hundreds of individuals.

    At the same time, invasive species such as the river Dreissena mollusk (Dreissena polymorpha) or the Chinese bough crab (Eriocheir sinensis) were also discovered: 96 species in total.

    During the period from 2007 to 2020, the concentration of oxygen dissolved in water has increased, and its quality has improved due to the equipment of several large enterprises with treatment facilities.

    However, problems remain. The level of nitrates from wastewater is increasing, and this will not change until at least 2025, when a new sewage system 24 km long and 61 m deep is to be put into operation in the metropolis. It will be able to collect 39 million tons of untreated wastewater annually, being simply dumped into the river.

    The situation is worse with the temperature rise in the Thames: by 0.2° C per year, which is a consequence of climate change.

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    Do you know that one of the main goals of food biotechnology is the liberation of territories from anthropogenic captivity to return to their nature (rewilding)? Read more here!

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