Determination of Microbial Production
177
4.4 Determination of Microbial Production
4.4.1 Introduction
Production of native aquatic microbial communities is one of the key problems in modern hydrobiology. The main goal of its measurement in the ambiental conditions of water basins is the evaluation of the speed of replenishment
of the stock of particulated food, directly assessable for aquatic fauna or via
the intermediate participation of phagotrophic protozoa. Microbial populations, which inhabit water columns, bottom sediments, detritus, periphytonic
turfs, as well as the microfiora of symbiotic animals, are among the most prominent components of aquatic ecosystems. Their functioning allows the energy
of the dead organic matter and of the organic matter excreted by hydrobionts,
like the energy of reduced inorganic compounds and juvenile gases exhaled
by the Earth mantle to be involved in bioproductivity processes. A large part
of primary organic matter is either autochthonous, produced by local phototrophs, or is allochthonous arriving in water basins from land and enter the
food webs of aquatic ecosystems via the microbial link, e.g. via its utilization
and biosynthetical transformation by the ambient microbial populations
(Sorokin 1965, 1971, 1978b; Pomeroy and Johannes 1968). The energy flow
schemes (Fig. 4.6) demonstrate that the main flow of energy passes via the
microbial compartments in all kinds of aquatic ecosystems, even in those of
the oceanic waters, where the direct grazing (pasture) food web prevails, to
say nothing of those in which the stock of dead organic matter produced
during spring blooms or brought from the land prevail as sources of primary
energy.
The above considerations make the importance of adequate assessment of microbial production quite obvious. Since the pioneering work
of Ivanov (1955), many efforts have been made to develop an adequate
universal methodology in this field, either with the use of radioisotopic or
direct microscopy techniques; but we still have no universal method. Each
of the existing methods has its faults and drawbacks and none can now
be recognized and accepted by the scientific community as universal. The
discussion centred on the methodological problems of measuring microbial
production still continues (Robarts and Zohary 1993). Among hundreds of
papers presenting the results of their determinations in various aquatic habitats, many concern or are completely dedicated to methodological problems.
For an inexperienced researcher it can be hard to understand which is most
appropriate. Controversy raged more strongly in the Western countries than
in the East, probably because of a somewhat euphoric acceptance in the West
of the thymidine method for measuring bacterial production. However,
this soon turned into skepticism because this new method appeared to be
hampered by drawbacks and uncertainties, which made the direct interpretation of its results practically impossible without intercalibration after older
177
4.4 Determination of Microbial Production
4.4.1 Introduction
Production of native aquatic microbial communities is one of the key problems in modern hydrobiology. The main goal of its measurement in the ambiental conditions of water basins is the evaluation of the speed of replenishment
of the stock of particulated food, directly assessable for aquatic fauna or via
the intermediate participation of phagotrophic protozoa. Microbial populations, which inhabit water columns, bottom sediments, detritus, periphytonic
turfs, as well as the microfiora of symbiotic animals, are among the most prominent components of aquatic ecosystems. Their functioning allows the energy
of the dead organic matter and of the organic matter excreted by hydrobionts,
like the energy of reduced inorganic compounds and juvenile gases exhaled
by the Earth mantle to be involved in bioproductivity processes. A large part
of primary organic matter is either autochthonous, produced by local phototrophs, or is allochthonous arriving in water basins from land and enter the
food webs of aquatic ecosystems via the microbial link, e.g. via its utilization
and biosynthetical transformation by the ambient microbial populations
(Sorokin 1965, 1971, 1978b; Pomeroy and Johannes 1968). The energy flow
schemes (Fig. 4.6) demonstrate that the main flow of energy passes via the
microbial compartments in all kinds of aquatic ecosystems, even in those of
the oceanic waters, where the direct grazing (pasture) food web prevails, to
say nothing of those in which the stock of dead organic matter produced
during spring blooms or brought from the land prevail as sources of primary
energy.
The above considerations make the importance of adequate assessment of microbial production quite obvious. Since the pioneering work
of Ivanov (1955), many efforts have been made to develop an adequate
universal methodology in this field, either with the use of radioisotopic or
direct microscopy techniques; but we still have no universal method. Each
of the existing methods has its faults and drawbacks and none can now
be recognized and accepted by the scientific community as universal. The
discussion centred on the methodological problems of measuring microbial
production still continues (Robarts and Zohary 1993). Among hundreds of
papers presenting the results of their determinations in various aquatic habitats, many concern or are completely dedicated to methodological problems.
For an inexperienced researcher it can be hard to understand which is most
appropriate. Controversy raged more strongly in the Western countries than
in the East, probably because of a somewhat euphoric acceptance in the West
of the thymidine method for measuring bacterial production. However,
this soon turned into skepticism because this new method appeared to be
hampered by drawbacks and uncertainties, which made the direct interpretation of its results practically impossible without intercalibration after older