Wildlife including seahorses and sharks call the Thames their home, after a report into the health of the river found it has a “rich and varied” ecosystem.
The State of the Thames report comes six decades after parts of it were declared “biologically dead”.
But the report also warned of the threats from climate change and pollution, with an average rise of water temperature of almost 0.2C per year found.
The Zoological Society of London conducted the first ever report on the state of the River Thames
Young short-snouted seahorses were found in 2017 at Greenwich and it “indicates that the tidal Thames is recovering estuarine ecosystem”, the report states.
There is also evidence on the importance of the river “as a breeding ground and nursery habitat for fish”, including smelt, European seabass and smoothhound, which is a type of shark.
The report, which was led by the Zoological Society of London (ZSL), stated that water quality has “exhibited some promising improvements”, with reduced phosphorus concentrations – a change attributed to the effectiveness of improved sewage treatment works to reduce harmful levels of nutrients entering the water.
There have been improvements in the habitats for seals and other mammals
However, there has been a long-term increase in nitrate and the report found the “influences of climate change are clearly impacting the tidal Thames, as both water temperature and sea levels continue to rise above historic baselines”.
When it comes to wildlife such as seals, there have been “improving short-term trends identified for natural habitats, birds and marine mammals”, although the number of fish species showed “a slight decline”, with more research needed to determine the cause”.
Between 2016 and 2020, 17,770 single-use plastic bottles were counted and removed at sites along the tidal Thames, almost half of which were water bottles, the report said.
It added that some plastics found in the river, including cotton buds and wet wipes, come from sewage overflowing into the estuary, which not only threatens the ecosystem but “also has a detrimental impact on the perception of the Thames as being ‘dirty’.”
The report found the water quality has ‘exhibited some promising improvements’
High levels of pollution in parts of the Thames led scientists in 1957 to declare stretches of it to be “biologically dead”, but there has been an improvement since then, the report said.
Alison Debney, ZSL conservation programme lead for wetland ecosystem recovery, said: “This report has enabled us to really look at how far the Thames has come on its journey to recovery since it was declared biologically dead, and in some cases set baselines to build from in the future.”
