The Thames, the iconic English river that flows through London, will witness a potential increase in algal blooms in the coming years courtesy climate change, a new study has warned.
This will happen even though the river’s water has seen a dramatic reduction in phosphorus loads in the last 40 years, as per the analysis. Phosphorus is needed for algal blooms to form.
Phosphorus loads have reduced by 80 per cent in the past four decades according to the study by lead author Helen Jarvie, professor in the Faculty of Environment and University Research Chair in Global Water Quality at the University of Waterloo, Canada.
The reduction is largely due to improved wastewater treatment and agricultural practices, a statement by the university noted.
“Rising river temperatures driven by climate change are increasing the risk of both spring diatom blooms and summer cyanobacterial blooms, the study found. These can have big impacts on the health of rivers, by shading out and suffocating aquatic life, using up oxygen in the water when they decompose, and being exposed to potentially toxic cyanobacteria,” the statement added.
Algal blooms also increase the cost of drinking water treatment and can limit recreational activities such as sailing, fishing and swimming. Controlling phosphorus from sewage discharges and agricultural runoff is a key strategy to reduce algal blooms in rivers and lakes, because the algae require phosphorus to grow.
“Despite huge successes in reducing phosphorus loads in the River Thames, phosphorus concentrations remain above levels that would limit algal growth and rising water temperatures are now increasing the potential for algal blooms in the river. Our results suggest that water quality management is now ‘treading water’ in a warming climate,” Jarvie said.
She added that her research documented 150 years of remarkable changes in river water quality. This was of particular importance and timeliness given the challenges the world now faced in managing water quality in a warming climate, and contemporary water quality concerns in Britain and around the world, she observed.
The study, A 150-year river water quality record shows reductions in phosphorus loads but not in algal growth potential, was recently published in Communications Earth & Environment. Jarvie’s co-authors include Fred Worrall, Tim P Burt & Nicholas J K Howden.