Tag Archives: Thames

Sharks and seahorses found living in the Thames waterway

After a period in which there seemed to be no hope for a ‘green’ Thames, the river is now booming with life, showing that environmental recovery is possible when serious conservation methods are enforced. However, concerns still exist about the health of the river.

Water levels have been increasing since monitoring began in 1911 in the Tidal Thames. Image credits: ZSL.

The Thames is, in many ways, the very lifeblood of the city of London. But being so close to the Industrial Revolution has come at a big price for the river’s natural inhabitants. By the 18th century, the Thames was one of the world’s busiest waterways, as London became the center of the vast British Empires. As more and more docks were built, more and more ships were sailed, and more and more coal was burned, the Thames suffered. The fact that the population of London and its industries discarded their rubbish in the river made things even worse. By the 19th century, the Thames was already horrid.

Things got a bit better in the 20th century as road transportation developed and river transportation became less prominent, but not much better. The river was declared “biologically dead” in 1957.

But in the past few decades, things started to change. Especially after 1990, conservation measures have borne fruit, and with stricter environmental regulations and careful management, the quality of the water has improved dramatically. We’ve reported in 2017 that delicate seahorses had been discovered in the waters of the Thames and now, a new report (State of the Thames Report, led by the Zoological Society of London or ZSL) notes that more unexpected species were discovered in the river’s waterways, including multiple bird species, eels and three different species of shark.

Venomous sharks

It’s the first major report on the Thames in 60 years, and there’s a lot to be happy about. There are now 115 fish and 92 bird species around the Thames. Seahorses, eels, seals and even sharks have been spotted. There’s even a porpoise population in the estuary river. The river is “home to myriad wildlife as diverse as London itself,” the report reads.

“The water quality of the Tidal Thames has exhibited some promising improvements. Dissolved oxygen concentrations, critical for fish survival, show long-term increases. Further, phosphorus concentrations have reduced in both the long and short term, showing the effectiveness of improved sewage treatment works to reduce harmful levels of nutrients entering water bodies,” the report reads.

The presence of sharks is perhaps the most curious. ZSL researchers believe the sharks use the Thames estuary to give birth and nurse their young — an indication that the water quality has improved substantially.

The Thames Estuary, where the river’s water flows into the sea. Image credits: NASA.

Sharks including the tope, starry smooth hound, and spurdog have been spotted in the Thames, although you’re unlikely to see them around London. The spurdog, in particular, is a rather interesting spotting.

The spurdog is a slender shark that feeds on bony fish and sometimes, even smaller sharks. It’s a vulnerable creature, hunted in some parts of the world for its fin. The spurdog is actually venomous — its spines in front of the two dorsal fins secrete a venom that can cause pain and swelling in humans.

There’s no reason to worry, however. While some outlets made it seem like London is teeming with big bad sharks, the truth is that sharks have not been spotted in London, but rather in the Thames Estuary. All in all, this is good news, because it shows that the river is teeming with life.

Alison Debney, for ZSL, said:

“Estuaries are one of our neglected and threatened ecosystems. They provide us with clean water, protection from flooding, and are an important nursery for fish and other wildlife. The Thames Estuary and its associated ‘blue carbon’ habitats are critically important in our fight to mitigate climate change and build a strong and resilient future for nature and people.”

“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.”

Not all good

However, some long-term trends are concerning in the Thames as well. In particular, researchers say, the number of fish is slowly declining, for reasons that are not exactly clear.

Climate change could be a major culprit. Temperatures in the Thames are rising by a whopping 0.2 °C a year, much faster than the global average. Sea levels are also increasing, by 4 mm a year. Just like in other parts of the world, this climate change is bringing with it extreme weather events and storms which may be affecting the local environment.

Plastic pollution was also found to be a problem, although researchers have only recently started gathering this type of data.

Image credits: ZSL.

The report also highlights the potential problems associated with London’s sewage and the need for the Thames Tideway Tunnel — often called London’s “super sewer” project. This £4.2bn, 15-mile (24km) long, 200ft (61m) deep sewer would capture 39 million tons of untreated sewage that currently makes its way into the Thames every year.

ZSL is also working to create special estuarine habitats. These would protect the Thames’ ecosystem, while also acting as a natural defense protecting London from water surges and storms.

Tower Bridge.

London’s waterways found to contain antibiotic-resistant bacterial genes

London’s waterways are rife with antibiotic resistant genes.

Tower Bridge.

Image via Pixabay.

The Regent’s Canal, Regent’s Park Pond, and the Serpentine contained high level of antibiotic resistance genes, a new study reports, but none were worse than the Thames. These genes encode resistance to common antibiotics such as penicillin, erythromycin, and tetracycline. They found their way into the water from bacteria in human and animal waste.

Laced waters

“This [study] shows that more research is needed into the efficiency of different water treatment methods for antibiotic removal, as none of the treatments currently used were designed to incorporate this,” says lead author Dr. Lena Ciric from UCL Civil, Environmental and Geomatic Engineering.

“This is particularly important in the case of water bodies into which we discharge our treated wastewater, which currently still contains antibiotics. It is also important to look into the levels of antibiotics and resistant bacteria in our drinking water sources.”

When humans or animals take antibiotics, part of the active substance gets excreted (while still active) into sewer systems and, from there, into freshwater sources. Once there, they’re exposed to bacteria and create an environment that favors resistant microbes. These will multiply faster than their non-resistant counterparts, making the resistance genes more prevalent in the total population. Resistant microbes can also share their resistance with their peers via lateral gene transfer.

The team developed a DNA-analysis method that can be used to measure the quantity of fourteen types of antibiotic resistance genes per liter of water. They then applied it in different water systems throughout London and compared the results. The Thames River had the highest level of antibiotic resistance genes, followed by The Regent’s Canal, Regent’s Park Pond, and the Serpentine. Antibiotics entering the sewer system are diluted through flushing, but even low levels can encourage resistance genes to multiply and spread to more microbes. The Thames is likely to have higher levels of antibiotics and resistant genes because a large number of wastewater treatment works discharge into it both upstream and in London.

The authors note that there is currently no legislation in place which specifies that antibiotics or the genes that encode their resistance need to be scrubbed from water sources. This could mean that antibiotics and said genes could be present in small amounts in drinking water, although this would require testing.

The team is now working on finding a way to remove antibiotics, resistant bacteria, and antibiotic-resistance genes from London’s natural water system using slow sand filtration, which is a form of drinking water treatment. This technique is already in use around the world including at Thames’ Coppermills Water Treatment Works, they explain, which provides drinking water for most of north east London. Their plan is to beef-up this filtration technique by tweaking the properties of the sand and activated carbon used in the filters, and by varying water flow rates.

The paper ” Use of synthesized double-stranded gene fragments as qPCR standards for the quantification of antibiotic resistance genes” has been published in the journal Journal of Microbiological Methods.