69
plankton is right and sufficient light energy is available to drive
the process.
If we think we need to know how much organic matter is provided
through phytoplankton excretion in natural water we must establish
rates for the algal species involved as function of the physiological
state of the algae, the nutrient levels in the water and other environmental factors such as temperature, light, turbulence, etc., and the
way these vary.
The relationship to nutrient levels and composition is probably
best studied in chemostats in the laboratory or even better by the
cage culture technique (Jensen e~ ai., 1972), which is ideal for excretion studies, provided the cages are operated in the continuous
reservoir mode which secures constant external nutrient levels througout the experiments.
It may strike the reader that the amount of infor~ation needed to
evaluate the production in natural waters may become unsurmountable if
we have to build up our estimates from detailed knowledge of all the
processes involved. We do not have to know how every screw is tightened and how much energy this requires in order to establish the production of cars by the automobile industry. Maybe we should look for
integrating parameters, and not so much for details in our efforts to
quantify aquatic production. Models based on input-output parameters
are easier to operate and may be readily tested, in contrast to mechanistic models which will remain oversimplifications, maybe forever.
LITERATURE REFERENCES
Aaronson, S. 1971: The synthesis of Extracellular Macromolecules and
Membranes by a Population of the Phytoflagellate OclVz.amOYLM darUc.a.
LilTInol. Oceanogr. 1 6, 1 - 9 •
Aaronson, S. 1978: Excretion of Organic Matter by Phytoplankton ~ v~o
Lirnnol. Oceanogr. 2 3, 838.
Aaronson, S. DeAngelis, B., Frank, O. and Baker, H. 1971: Secretion of
Vitamins and Amino Acids into the Environment by Oc.MomOYLM darUc.a.
J. Phycol. 7, 215-218.
Berman, T. and Holm-Hansen, O. 1974: Release of Photoassimilation Carbon
as dissolved Organic Matter by Marine Phytoplankton. Marine Biol.
28, 305-310.
plankton is right and sufficient light energy is available to drive
the process.
If we think we need to know how much organic matter is provided
through phytoplankton excretion in natural water we must establish
rates for the algal species involved as function of the physiological
state of the algae, the nutrient levels in the water and other environmental factors such as temperature, light, turbulence, etc., and the
way these vary.
The relationship to nutrient levels and composition is probably
best studied in chemostats in the laboratory or even better by the
cage culture technique (Jensen e~ ai., 1972), which is ideal for excretion studies, provided the cages are operated in the continuous
reservoir mode which secures constant external nutrient levels througout the experiments.
It may strike the reader that the amount of infor~ation needed to
evaluate the production in natural waters may become unsurmountable if
we have to build up our estimates from detailed knowledge of all the
processes involved. We do not have to know how every screw is tightened and how much energy this requires in order to establish the production of cars by the automobile industry. Maybe we should look for
integrating parameters, and not so much for details in our efforts to
quantify aquatic production. Models based on input-output parameters
are easier to operate and may be readily tested, in contrast to mechanistic models which will remain oversimplifications, maybe forever.
LITERATURE REFERENCES
Aaronson, S. 1971: The synthesis of Extracellular Macromolecules and
Membranes by a Population of the Phytoflagellate OclVz.amOYLM darUc.a.
LilTInol. Oceanogr. 1 6, 1 - 9 •
Aaronson, S. 1978: Excretion of Organic Matter by Phytoplankton ~ v~o
Lirnnol. Oceanogr. 2 3, 838.
Aaronson, S. DeAngelis, B., Frank, O. and Baker, H. 1971: Secretion of
Vitamins and Amino Acids into the Environment by Oc.MomOYLM darUc.a.
J. Phycol. 7, 215-218.
Berman, T. and Holm-Hansen, O. 1974: Release of Photoassimilation Carbon
as dissolved Organic Matter by Marine Phytoplankton. Marine Biol.
28, 305-310.