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Zebra Mussels
Zebra Mussels are a
non-native invasive species, probably introduced into Cardiff Bay on
a visiting vessel. They reproduce rapidly, and can cause problems if
appropriate care is not taken.
This notification is designed to advise water users on the legal
implications and outlines measures
to be taken in order to protect water users, and prevent the spread
of the mussels as much as possible.
Advice to water users
1. It is an offence under the Wildlife and Countryside Act 1981 to
release, or allow to escape into the wild, any animal which is not
ordinarily resident in and is not a regular visitor to Great Britain
in a wild state. Zebra mussels are such animals.
2. Boat owners have a responsibility to prevent the spread of these
mussels. See FAQ's below for advice on how to prevent the spread.
3. Zebra mussels grow rapidly and in large masses, which can lead to
blockages or restrict engine cooling water intakes, resulting in
engines over-heating. They can foul the hull of vessels. Routine
maintenance of vessels will limit this build-up and prevent such
problems occurring.
4. Zebra mussels have very sharp-edged shells. These mussels will
grow on mooring ropes, boat hulls and submerged equipment. Care
should be taken to avoid cuts when handling objects that have been
submerged in the water.
5. Although Zebra mussels are found at other sites in the UK,
Cardiff Bay is the first site to record them in Wales. To minimise
the transfer of this species to other freshwater sites, care should
be taken when transporting vessels. When ashore, the hull should be
inspected and cleared of any attached mussels. Bilge water should be
drained out and the bilges rinsed with dilute bleach solution,
allowed to soak for one hour and drained. (See FAQ’s for further
information)
6. All personal watercraft (e.g. canoes and dinghies) that have been
in Cardiff Bay water for any length of time should be washed down
using a sponge and dilute solution of bleach before moving the boat
to any other fresh water. Do not allow bleach solution to enter
Cardiff Bay or other watercourses.
Frequently asked questions:
Q: What is a nuisance invasive species?
A: When a species (plant, animal, fish or microscopic
organism), that is not native to an area, is introduced, with the
potential to cause problems.
Q: How did they get into Cardiff bay?
A: Zebra mussels are a non-native invasive species, probably
introduced into Cardiff Bay on a visiting vessel. They reproduce
rapidly, and can cause problems if appropriate care is not taken.
Q: How do Zebra mussels spread in freshwater locations?
A: Adult Zebra mussels attached to boat hulls are transported
from location to location. During summer, larvae may be transported
in bilge water and released on exchange of water at the new
location. Adults, and to a lesser extent larvae, can be spread on
items of equipment moved from infected areas into Zebra mussel free
areas e.g. fishing gear, pipes, tanks and moorings etc.
Q: What other locations already have the Zebra mussels:
A: Zebra mussels are native to the Caspian and Black sea
basins. They moved across Europe with the constructions of the
canals during 1700’s and reached England by 1824. They were
introduced to the USA in the 1980’s. Zebra mussels have also been
present in Lough Erne, Ireland, since 1993/4. In 2002 a study
recorded their presence in the River Thames and Lea, and Lake
Barden, Kent. They have also been sighted in Yorkshire and
Cambridgeshire.
Q: What is the lifespan of Zebra mussels?
A: Adults can live for several days to a couple of weeks out of water
if they remain moist. This means they can be easily transported from
one water area to another on boats and equipment transported by
road.
Q: Are they edible?
A: All shellfish layings have to be approved by the relevant Local
Authority in consultation with the Foods Standards Agency. Part of
the approval process involves sampling of the shellfish to ensure
they are fit for human consumption. There are no approved shellfish
layings within Cardiff Bay and therefore members of the public
should be advised that the shellfish in Cardiff Bay are not safe to
eat.
Q: Why is it my responsibility as a boat owner to prevent the
spread?
A: It is an offence under the Wildlife and Countryside Act
1981 to release, or allow to escape into the wild, any animal which
is not ordinarily resident in and is not a regular visitor to Great
Britain in a wild state. Zebra mussels are such animals.
There are environmental concerns associated with Zebra mussels. As
each individual can filter between 1 and 2 litres of water per day,
this removes algae and other aquatic organisms important for the
thriving fish and bird populations in Cardiff Bay. Cardiff Harbour
Authority is implementing a programme to assess implications.
Q: How can I prevent the spread and introduction of Zebra
mussels into other waters?
A: The following are recommended actions for water users:
1. Keep boats free of Zebra mussels.
2. Regularly bring boats ashore and pressure wash the hull, rinsing
bilges with DILUTE bleach solution.
3. Ensure all weeds are removed from boats and trailers before
leaving Cardiff Bay and travelling to a new location.
4. If possible allow the boat to dry out for at least a week before
launching at any other freshwater site.
5. Ensure the hull is free of Zebra mussels before moving to any
other fresh water.
Q: What actions are recommended for me to comply with the
legislation mentioned above?
A: Calculate if your vessel has been in Cardiff Bay for a period longer
than 2 – 3 weeks.
a. If the duration of stay in Bay water is less than that time,
follow the instructions above.
b. If the duration of stay in Bay water has been longer than 2 – 3
weeks, follow the instructions below:
For vessels with bilges:
*
Visit the Harbour Authority bilge pump out facility, pump out and
rinse the bilges with DILUTE bleach solution, standing for an hour
and finally pumping out using the pump out facility. Do not allow
bleach solution to enter Bay water.
For vessels without bilges:
*
It should be removed from the Bay, and washed down using a sponge
and DILUTE SOLUTION of bleach before moving the boat to any other
fresh water, therefore avoiding run-off of excess bleach solution
into watercourses.
*
At all times water users should comply with the Environment Agency
Pollution Prevention Guideline document PPG 14 Marinas and Craft.
PPG’s are available for download from the following sites:
www.environment-agency.gov.uk
www.sepa.org.uk
www.ehsni.gov.uk
Q: What is Cardiff Harbour Authority doing to prevent the
spread of Zebra mussels?
A: Cardiff Harbour Authority is following the guidance set
out above and ensuring that its own activities do not cause the
spread of this species to other water bodies. Furthermore it is also
minimising the impact within Cardiff Bay.
Environmental responsibility is a key part of our strategy, in both
the short and longer term. The Harbour Authority already provides
access to its bilge pump out facility. In addition, a jet washing
facility is available for use as vessels leave the water. Warning
signs have also been erected at boat entry/exit points around the
Bay.
General information
In 2004 the Harbour
Authority discovered the presence of zebra mussels in the Bay. These
mussels are a non-native invasive species, probably introduced into
Cardiff Bay via a visiting vessel. The mussels reproduce rapidly and
can cause problems for water users if appropriate care is not taken.
They are an “Alien Species” within the meaning of the Wildlife and
Countryside Act 1981 and are regarded as a pest.
This is the first confirmed sighting of Zebra mussels in Wales .
Previously they have been observed in the River Thames and Lea, and
Lake Barden , Kent . They have also been sighted in Yorkshire,
Cambridgeshire and Ireland .
Enormous quantities of mussels have been found clinging to
underwater structures on the barrage and coating the diffusers and
pipes of the aeration system. Zebra mussels have economic importance
by causing, amongst other things, blockage of water intake pipes
resulting in large expenditure on preventative maintenance. Within
Cardiff Bay the main effects are predicted to be associated with
growth on solid structures such as pontoons, mooring ropes and
ground tackle where care will need to be taken to avoid severe cuts
from the mussels razor sharp shell and also growth on structures
such as the Barrage sluices and Fish pass where the combined weight
of a large number of mussels may interfere with proper movement of
the structure. Approximately five tonnes of mussels were removed
during maintenance of the sluices and fish pass in 2006 and a
further five tonnes is expected to require removal early in 2007.
Both Pleasure and commercial boat owners should be aware that the
mussels can grow and cause partial or complete blockage of submerged
cool water intake and discharge pipes including the intakes in the
legs of outboard engines. Mariners should therefore pay increased
attention to their engine cooling water systems.
The Harbour Authority Environment Team is currently monitoring
mussel numbers and distribution and working with Barrage Control to
investigate an effective anti-fouling product to prevent mussels
from covering and interfering with barrage structures and mechanics.
The Harbour Authority is also funding a 3 year Phd study in
conjunction with Cardiff University to investigate the number and
spread of zebra mussels in Cardiff Bay , how they are interacting
with other aquatic organisms present, and whether any control
measures could be implemented to minimise the detriment caused by
these creatures.
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