Discussion
257
designed to study the rate of nutrient utilization and cycling and concomitant growth of mixed
microbial populations as functions of pertinent environmental parameters. Another simulator to study
higher trophic levels is under consideration and hopefully will provide useful information concerning
the effects of higher trophic levels. However, in the final analysis, the ecological connections between
dynamic behavior of microbial populations and higher trophic levels will be most likely determined by
field studies rather than simulators.
With regards to the simulation of solar radiant energy, matching total flux is no problem. What is
difficult and what we are currently attempting to do is to reproduce the spectral distribution of solar
energy flux as well as total intensity.
R. Mitchell, USA.
The modellers of ecosystems only take into account very conventional parameters. However, one
may omit from an equation an essential parameter. We have shown that bacteria have chemoreceptors
which enable them to detect food sources. The rate of biodegradation is dependent on both the
enzyme system and the receptors. Pollutants, including hydrocarbons, pesticides and heavy metals
destroy the receptors without killing the bacteria. This type of aberration caused by stress would not
be shown in the model. If ecosystem is to have any meaning these behavioural effects must be taken
into account.
Author's Comments on the Edited Discussion by R. Mitchell, USA.
The ecosystem simulator was not designed to be an isolated research tool but is meant to be used as
a major component of a integrated research program which includes bench scale laboratory experiments and field studies. Obviously, mechanistic studies referred to above should be done using bench
scale experiments. The appropriate use of this simulator in relation to the effects of pesticides, etc., is
to provide information on the resultant macroscopic or integrated ecosystem which are the end result
of the mechanisms which operate on the microscopic level.
REFERENCES
1. EICHENBERGER, E. "Ökologische Untersuchungen an Modellfliessgewässern" Schweizerische'
Zeitschr. f. Hydrologie 29 (1967), 1
2. LIEBMANN, H., SCHERB, K., RIETZ, K. "Möglichkeiten experimenteller Fliesswasserforschung
an der Vorfluter-Anlage Grosslappen" Wasser-und Abwasser-Forschung 2 (1969), 3
3. SANDERS, W.M. and FALCO, I.W. "Ecosystem simulation for water pollution research" Sixth
International Conference on Water Pollution Research, 1972.
-(•Institut für Wasser-, Boden- und Lufthygiene des Bundesgesundheitsamtes (Institute of Water, Soil,
and Air Hygiene, Federal Health Office), Berlin-Dahlem, Corrensplatz 1.
257
designed to study the rate of nutrient utilization and cycling and concomitant growth of mixed
microbial populations as functions of pertinent environmental parameters. Another simulator to study
higher trophic levels is under consideration and hopefully will provide useful information concerning
the effects of higher trophic levels. However, in the final analysis, the ecological connections between
dynamic behavior of microbial populations and higher trophic levels will be most likely determined by
field studies rather than simulators.
With regards to the simulation of solar radiant energy, matching total flux is no problem. What is
difficult and what we are currently attempting to do is to reproduce the spectral distribution of solar
energy flux as well as total intensity.
R. Mitchell, USA.
The modellers of ecosystems only take into account very conventional parameters. However, one
may omit from an equation an essential parameter. We have shown that bacteria have chemoreceptors
which enable them to detect food sources. The rate of biodegradation is dependent on both the
enzyme system and the receptors. Pollutants, including hydrocarbons, pesticides and heavy metals
destroy the receptors without killing the bacteria. This type of aberration caused by stress would not
be shown in the model. If ecosystem is to have any meaning these behavioural effects must be taken
into account.
Author's Comments on the Edited Discussion by R. Mitchell, USA.
The ecosystem simulator was not designed to be an isolated research tool but is meant to be used as
a major component of a integrated research program which includes bench scale laboratory experiments and field studies. Obviously, mechanistic studies referred to above should be done using bench
scale experiments. The appropriate use of this simulator in relation to the effects of pesticides, etc., is
to provide information on the resultant macroscopic or integrated ecosystem which are the end result
of the mechanisms which operate on the microscopic level.
REFERENCES
1. EICHENBERGER, E. "Ökologische Untersuchungen an Modellfliessgewässern" Schweizerische'
Zeitschr. f. Hydrologie 29 (1967), 1
2. LIEBMANN, H., SCHERB, K., RIETZ, K. "Möglichkeiten experimenteller Fliesswasserforschung
an der Vorfluter-Anlage Grosslappen" Wasser-und Abwasser-Forschung 2 (1969), 3
3. SANDERS, W.M. and FALCO, I.W. "Ecosystem simulation for water pollution research" Sixth
International Conference on Water Pollution Research, 1972.
-(•Institut für Wasser-, Boden- und Lufthygiene des Bundesgesundheitsamtes (Institute of Water, Soil,
and Air Hygiene, Federal Health Office), Berlin-Dahlem, Corrensplatz 1.