Some like it hot, but our wetlands do not

Heatwaves can spell trouble for our freshwater habitats, as The Wildlife Trusts’ Water Policy Manager Ali Morse explains.

Hot summer days might seem like a blessing. People flock to the beach, flowers bloom and insects thrive, providing food for birds and bats. But a warm summer can be an issue for other species, particularly those that rely on our rivers and wetlands.

When it gets hot, water can’t hold as much oxygen, which can have devastating consequences for wildlife. By June this year, fish were suffocating in the warmer water and the Environment Agency had to use aerators in some waterbodies to supply them with oxygen. The warm weather also meant that blue-green algae bloomed in lakes and reservoirs across the UK. This outcompetes other plants and can be toxic to human and animal health.

Impacts like these often hit the headlines in brief hot periods, but they can also be a sign of longer-term shifting weather patterns, with risks for a whole host of river and wetland species.

Extreme weather

Despite the frequent downpours of June, spring rainfall was lower than average; the winter was dry and last summer we experienced a heatwave. It has either been dry – or very, very wet. When rainfall is intense it rapidly runs off the land, quickly being conveyed out to sea rather than soaking into soils and slowly replenishing rivers, wetlands and the layers of water-holding rock (known as aquifers) beneath them.

When river levels can’t be sustained, due to rainfall being either absent or too intense, a host of problems can arise:

  • With less water present, pollutants become more concentrated
  • More sediment sinks to the bottom, which can choke the insects and fish eggs found within
  • Fish and other species may become trapped as water levels drop, imprisoned by barriers like weirs that they can no longer get past
  • Conditions may favour the spread of invasive non-native species, like Himalayan balsam that can quickly colonise newly-exposed banks at the expense of native plants
  • Sections of river may become uninhabitable for species that rely on a particular depth or water quality
  • Wetlands suffer too, as habitats dry out and trees and scrub encroach. Habitat for amphibians, aquatic insects and wetland plants may be lost

And these problems don’t just affect wildlife. The water sources that supply our rivers and wetlands, plus the rivers themselves, are also the source of our drinking water. If these water sources aren’t in good condition, they are less able to provide the water we need.

What needs to change?

With the potential for extreme weather systems (like heatwaves and heavy rain) growing, we need to rethink the way we use our water.

Government have already pledged to make the amount of water we take from the environment (known as water abstraction) more sustainable, by making changes to licences that currently allow a damaging amount of water to be removed from our rivers.

This would create a shortfall for water companies, but they are investing in plugging this ‘gap’ by continuing to reduce leaks from their network of supply pipes, so that less water is needed in the first place. They’re also planning to manage our scarce resources better, including by having water-rich companies share water with others who are short. This will all leave more water in the environment for wildlife like water voles and toads, two of the stars of our Wind in the Willows film


How can we help?

It’s easy to criticize the water industry for taking too much water, but we often forget that they do so because society demands its. In the UK we use more water per person than almost all other countries in Europe. For something that’s so essential to our lives, water is surprisingly cheap, and we need to value it more and waste it less. Every drop we waste is a drop lost from our rivers, streams and wetlands.

A new campaign, Love Water, has been launched to help. Backed by more than 40 environmental groups, charities, water companies and regulators, the campaign asks the British public to help preserve water resources for future generations by raising awareness of the importance of water and the role everyone plays in protecting it.

Many of the solutions are simple, like turning off the tap when you brush your teeth – if everyone in the UK did this we’d save 1,584,000,000 litres (1,584 megalitres) of water a day! We’ve pulled together some tips for conserving water here.