Monitoring the Responses of Freshwater Ecosystems to Climate Change - Climate Change Impacts on Freshwater Ecosystems - page 90

Table 5.1 ( Cont'd )

Category Response Indicator Justification of indicator c t w

Water temperature
effects on
zooplankton

Higher water temperature
leads to shifts in zooplankton
community composition.
Higher, earlier population
growth rates of Daphnia and
earlier summer decline occur
due to higher spring
temperatures. As a result,
higher Daphnia biomass leads
to earlier phytoplankton
suppression and a shift from a
dominance of large-bodied to
smaller species.

Zooplankton
biomass and
composition, size
classes

The response of
zooplankton (although
not monitored for the
Water Framework
Directive) might be a
good indicator for
changes in food web
dynamics due to
temperature increase.

(x) x (x)

Water temperature
effects on cold water
fish

Higher water temperatures
(especially in the epilimnion)
lead to the progressive
reduction of thermal habitats
for, e.g. Salvelinus
namaycush . As a result,
cold-water species will
disappear from littoral areas
in spring and summer.
Furthermore, higher water
temperatures will reduce
reproduction success of
cold-water species and
increase parasitic and
predator pressure on the egg
and young life stages.

Summer water
temperature or air
temperature

Water temperature is
easy to measure, but even
air temperature reflects
warming up of mixed
layer temperature.

x x

Secondary
production