Catherine Burbage - 10-Jul-2007
- Experts at the Environment Agency are
urging people not to introduce alien plants
into garden ponds or other water bodies,
to help prevent the loss of precious native
wildlife.
Several non-native species, which can often
be bought in garden centres, can cause devastation
to wildlife as they grow at such an alarming
rate. Not only are garden ponds affected,
but careless disposal of pond waste and
water means these plants can get into local
waters too.
As they begin to cover the water’s surface
they stop light getting into the water,
killing underlying plants and removing any
oxygen. This can cause the death of fish,
frogs, toads, newts and invertebrates and
can cause a hazard for children, pets and
livestock who may mistake the dense green
surface for grass or gravel and end up in
the water.
The main culprits to look out for are:
Australian swamp stonecrop (Crassula helmsii)
Originally from Tasmania, this plant spreads
rapidly to form dense, interwoven mats and
has driven some rare species to extinction.
It is easily spread and grows over other
aquatic vegetation, killing native plants
and removing oxygen vital for fish and invertebrates.
Floating Pennywort (Hydrocotyle ranunculoides)
Floating Pennywort causes problems wherever
it is introduced, often costing thousands
of pounds worth of damage. This plant blocks
waterways, causes flooding, chokes out all
submerged and most riverside plants and
prevents navigation and fishing.
Parrot’s Feather (Myriophyllum aquaticum)
Widely available in garden centres, Parrot’s
feather grows so quickly that it can cover
large ponds within a year, killing plants
and removing oxygen essential for fish and
amphibians.
Water fern (Azolla filiculoides)
Dense mats of water fern can completely
cover the surface of a pond or river, reducing
light beneath the surface and killing submerged
plants and fish. These mats can also be
mistaken for grass by animals and children,
who risk drowning if they try to walk on
the surface. Floating rafts of water fern
can also block sluices and locks.
Chris Extence ecological appraisal specialist
for the Environment Agency said: ‘These
species can be devastating to local pond
and river wildlife, so we are urging people
not to buy these or any other non-native
species. Good alternatives such as spiked
water milfoil, hornwort and marsh pennywort
are widely available and just as attractive.
‘If you have any of these non-native plants
in your garden pond, then the best way to
get rid of them is to pull them out by hand,
then dry and burn them, or compost them.
Don’t throw them away, or put them near
rivers or ponds, as they can have severe
consequences for local wildlife.’
The Environment Agency is currently working
to remove these and other species from rivers
to help meet the requirements of the Water
Framework Directive (WFD). The WFD is a
piece of European legislation that aims
to establish better ways to protect our
water environment and focus on the 'health'
of the water around us. Programmes are underway
to remove alien species from particular
sections of water, but one of the main things
which will make a difference is if people
stop adding these plants to their ponds
For more information on how to recognise
and control these invasive species, visit
www.environment-agency.gov.uk/subjects/conservation
or the Centre for Aquatic Plant management
at www.capm.org.uk
