Monitoring the Responses of Freshwater Ecosystems to Climate Change - Climate Change Impacts on Freshwater Ecosystems - page 100

Table 5.2 ( Cont'd )

Category Response Indicator Justification of indicator c t w

Replacement of
salmonid by cyprinid
fish species

Higher water temperatures
will reduce reproductive
success of salmonid species
and increase parasitic and
predator pressure on the
egg and young larval
stages. Warm water
cyprinid species will invade
in cold water regions.

Water
temperature
(maximum and
minimum
monthly values);
fish species
composition

The eggs of salmonid
species need high oxygen
concentrations, which will
be reduced by higher
water temperatures.
Parasites and fungi
benefit from high
temperatures.

x x (x)

Standing stock of
cold water fish

Brook trout populations
could either benefit from
increased growth rates in
spring and fall or suffer
from shrinking habitat and
reduced growth rates in
summer, depending on the
magnitude of temperature
change and on food
availability.

Abundance and
biomass of
brook trout

Brook trout is a keystone
species in most Northern
European countries.

x x (x)

Spread of alien
species

Higher temperatures often
favour alien species that
increasingly colonize small
streams. These could be
alien fish, macrophyte or
macroinvertebrate species.

Water
temperature
(maximum and
minimum
monthly values);
share of alien
species in the
community

The survival and
reproduction of several
alien species in temperate
ecoregions is controlled
by minimum
temperatures. The second
parameter can often be
inferred from routine
monitoring for the Water
Framework Directive.

(x) x x

Category: ecosystem component being affected by direct or indirect climate change effects. Response: describes how the variables change under the
stressor considered. Indicator: a judgemental selection of the variables that most clearly reflect climate change.