Figure 4 . Simplified representation of complex (eco-)system interrelations with regard to a pollutant, and
consequences for bioindication and biomonitoring (from Markert, 1996). As a rule, it is assumed that a
pollutant affects an organism (bioindicator/biomonitor). Both the organism and the pollutant interact closely
with other ecosystem compartments. The life activity of the organism is therefore influenced by a great
number of abiotic and biotic factors and may often be subject to the action of several pollutants, especially
under “ natural” field conditions. W ith regard to the interpretation of the “ information” given by
the bioindicator/biomonitor, the problem often arises as to where the change observed or measured
in the bioindicator/biomonitor really originates. Even a combined multifunctional and multi-structural view
of the various ecosystem compartments has often left individual operative mechanisms unex plained . W hat
makes matters even more difficult is that the pollutant to be monitored is in close competition with all
other environmental compartments. So it is by no means certain, although rather probable, that pollutant
A does not interact synergistically or antagonistically with pollutant B. Moreover, the absorption, location
and metabolism of both have not yet been adequately described. However, pollutant A may also affect
other biota, which may react even more sensitively to A than the bioindicator itself. If this sensitivity results
in a change in the population density of a more sensitive organism, the occurrence of the bioindicator itself
may also be affected, at least if the former is in direct or indirect competition with the latter. The question
remains as to whether it is possible at all to make a statement about the current condition of the ecosystem
as a whole by ex amining a single bioindicator
Figure 4 . Simplified representation of complex (eco-)system interrelations with regard to a pollutant, and
consequences for bioindication and biomonitoring (from Markert, 1996). As a rule, it is assumed that a
pollutant affects an organism (bioindicator/biomonitor). Both the organism and the pollutant interact closely
with other ecosystem compartments. The life activity of the organism is therefore influenced by a great
number of abiotic and biotic factors and may often be subject to the action of several pollutants, especially
under “ natural” field conditions. W ith regard to the interpretation of the “ information” given by
the bioindicator/biomonitor, the problem often arises as to where the change observed or measured
in the bioindicator/biomonitor really originates. Even a combined multifunctional and multi-structural view
of the various ecosystem compartments has often left individual operative mechanisms unex plained . W hat
makes matters even more difficult is that the pollutant to be monitored is in close competition with all
other environmental compartments. So it is by no means certain, although rather probable, that pollutant
A does not interact synergistically or antagonistically with pollutant B. Moreover, the absorption, location
and metabolism of both have not yet been adequately described. However, pollutant A may also affect
other biota, which may react even more sensitively to A than the bioindicator itself. If this sensitivity results
in a change in the population density of a more sensitive organism, the occurrence of the bioindicator itself
may also be affected, at least if the former is in direct or indirect competition with the latter. The question
remains as to whether it is possible at all to make a statement about the current condition of the ecosystem
as a whole by ex amining a single bioindicator
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