Download USING OPTION 1

USING OPTION 1
EARLY STAGES
UK Technical Advisory Group (UKTAG)
 UKTAG Alien Species Group (ASG)
 Initial choices – what to do about alien
species and WFD classification

INITIAL CHOICES - A

Do not address alien species at all under
the WFD
INITIAL CHOICES - A

Do not address alien species at all under
the WFD
X
INITIAL CHOICES - B

Do not use alien species at all for
classifying ecological status, but identify
water bodies at risk from alien species and
attempt to tackle them through
programmes of measures
INITIAL CHOICES - B

Do not use alien species at all for classifying
ecological status, but identify water bodies at
risk from alien species and attempt to tackle
them through programmes of measures
X
INITIAL CHOICES - C

Use alien species in ecological status
classification, but only with respect to high
status
INITIAL CHOICES - C

Use alien species in ecological status
classification, but only with respect to high
status
X
INITIAL CHOICES - D

Use alien species in ecological status
classification both for high ecological
status and good ecological status.
Downgrade from high or good status only
when established species are shown to be
having a significant impact on the water
body
INITIAL CHOICES - D

Use alien species in ecological status
classification both for high ecological status and
good ecological status. Downgrade from high or
good status only when established species are
shown to be having a significant impact on the
water body
X
INITIAL CHOICES - E

Use alien species in ecological status
classification both for high ecological
status and good ecological status.
Downgrading from high status need not
depend on demonstrated impact;
demonstrated impact is needed to
downgrade from good status
INITIAL CHOICES - E

Use alien species in ecological status
classification both for high ecological status and
good ecological status. Downgrading from high
status need not depend on demonstrated
impact; demonstrated impact needed to
downgrade from good status

HIGH STATUS
WFD concept
 ‘Reference condition’ = ‘high status’
 ‘Taxonomic composition –’totally or nearly
totally undisturbed’
 Can any alien species even be present at
high status?

ECOLOGICAL STATUS: PRINCIPLES
High ecological status

A water body classified as being at high
status (i.e. in reference condition) should
contain no established alien species
known to cause serious impacts to water
bodies
HIGH-IMPACT SPECIES

Australian swamp stonecrop (Crassula

Water fern (Azolla filiculoides)
helmsii)
North American signal crayfish
(Pacifastacus leniusculus)
 Chinese mitten crab (Eriocheir sinensis)
 Topmouth gudgeon (Pseudorasbora parva)

ECOLOGICAL STATUS: PRINCIPLES
Good ecological status

A water body that demonstrates more
than a slight adverse impact from one or
more established alien species on the
high-impact list is considered to be failing
to achieve good status
CLASSIFICATION PROCEDURE
USING OPTION 1
Is there evidence
that a listed highimpact alien species
is established in the
water body?
No
Yes
No
Classify as
high status
Yes
Yes
Is there evidence that
the alien species is
causing more than a
slight adverse impact
on any biological
element?
Is there other
evidence that would
prevent the water
body being classed
as high status?
No
Is there other
evidence that would
prevent the water
body being classed
as good status?
No
Classify as
good status
Yes
Classify as
moderate
or worse
CASE STUDIES Tiel Burn, Perthshire, central Scotland
 River Earn, Perthshire, central Scotland
 Both classified at good or high ecological
status using biological classification tools
 Signal crayfish established


Downgraded to moderate using Option 1