Introduction
155
of 1 % of the aquatic microbes may really grow in these media; but a strange
contaminating microfiora grows readily on them, which enters the water from
ships or shore. This has created much confusion in previous studies of aquatic
microfiora based on traditional microbiology. Perhaps the most remarkable
example of such a misguided interpretation connected with the wide-scale use
of the plate count technique in marine microbiology is the monograph by Kriss
(1963) on marine microbiology, which does not contain a single item of valid
data in the whole large volume but a lot of anecdotes. For example, in this
book, the colloblasts of ctenofores were described as the new class of marine
bacteria (Krasilnikovia), and the golden image of this ctenophore's detail
decorates the cover of this fanciful account.
With the use of radioisotopes, it is possible to almost completely avoid
traditional microbiological methods in solving the above-listed problems of
aquatic microbial ecology; and, unlike the latter, radioisotopic methods
provide the key to obtaining adequate quantitative data. For example, the
spatial distribution of various kinds of heterotrophic bacteria in water bodies
can be easily determined with the use of 14C-methodology, thus replacing the
tedious procedure of traditional plate counts.
The second important point, which has to be clearly realized when using
radioisotopic methods in the field, especially at an early stage, is the selection
of the most appropriate technique to solve a given problem. Some of them
may be resolved during the estimation of only a relative parameter of substrate uptake or CO2 or release rates. To solve others, only their absolute values
are suitable. The basic difference is that in the first case the specific radioactivity of substrates consumed or released by natural aquatic microfiora can be
ignored. Only its approximate range should be known to the researcher for
the experiments. In the second case, e.g., for measuring the absolute rates of
the processes, the researcher must know the exact specific radioactivity of
these substrates, taking into account their pools in situ.
In conclusion, it will be useful to present here some general information
about aquatic microfiora. The term aquatic microfiora unites aquatic bacteria
(heterotrophic, chemoautotrophic, photoautotrophic, and others), aquatic
yeasts, and aquatic fungi (molds and actinomycetes). Pelagic microfiora, which
lives permanently in the water column, is related to bacterioplankton. This
term, synonymous with phytoplankton in relation to pelagic algofiora, was
coined in 1932 by the Russian professor A. Rasumov, who first discovered that
microfiora of natural waters is represented by millions of cells per 1 ml, and
not by hundreds after plate counting (Rasumov 1932). He also first used membrane filters, which were invented by the Russian microbiologists Dianova and
Voroshilova. He stained bacteria on filters with erythrosine stain and made
them transparent with immersion oil (Sorokin and Kadota 1972). Using
Rasumov's method, Russian hydrobiologists published during the 1950s to the
1970s numerous papers on the density and spatial distribution of bacterioplankton and its production, the latter being estimated after the method
devised by Ivanov (1955) and based on the use of Rasumov's method.
155
of 1 % of the aquatic microbes may really grow in these media; but a strange
contaminating microfiora grows readily on them, which enters the water from
ships or shore. This has created much confusion in previous studies of aquatic
microfiora based on traditional microbiology. Perhaps the most remarkable
example of such a misguided interpretation connected with the wide-scale use
of the plate count technique in marine microbiology is the monograph by Kriss
(1963) on marine microbiology, which does not contain a single item of valid
data in the whole large volume but a lot of anecdotes. For example, in this
book, the colloblasts of ctenofores were described as the new class of marine
bacteria (Krasilnikovia), and the golden image of this ctenophore's detail
decorates the cover of this fanciful account.
With the use of radioisotopes, it is possible to almost completely avoid
traditional microbiological methods in solving the above-listed problems of
aquatic microbial ecology; and, unlike the latter, radioisotopic methods
provide the key to obtaining adequate quantitative data. For example, the
spatial distribution of various kinds of heterotrophic bacteria in water bodies
can be easily determined with the use of 14C-methodology, thus replacing the
tedious procedure of traditional plate counts.
The second important point, which has to be clearly realized when using
radioisotopic methods in the field, especially at an early stage, is the selection
of the most appropriate technique to solve a given problem. Some of them
may be resolved during the estimation of only a relative parameter of substrate uptake or CO2 or release rates. To solve others, only their absolute values
are suitable. The basic difference is that in the first case the specific radioactivity of substrates consumed or released by natural aquatic microfiora can be
ignored. Only its approximate range should be known to the researcher for
the experiments. In the second case, e.g., for measuring the absolute rates of
the processes, the researcher must know the exact specific radioactivity of
these substrates, taking into account their pools in situ.
In conclusion, it will be useful to present here some general information
about aquatic microfiora. The term aquatic microfiora unites aquatic bacteria
(heterotrophic, chemoautotrophic, photoautotrophic, and others), aquatic
yeasts, and aquatic fungi (molds and actinomycetes). Pelagic microfiora, which
lives permanently in the water column, is related to bacterioplankton. This
term, synonymous with phytoplankton in relation to pelagic algofiora, was
coined in 1932 by the Russian professor A. Rasumov, who first discovered that
microfiora of natural waters is represented by millions of cells per 1 ml, and
not by hundreds after plate counting (Rasumov 1932). He also first used membrane filters, which were invented by the Russian microbiologists Dianova and
Voroshilova. He stained bacteria on filters with erythrosine stain and made
them transparent with immersion oil (Sorokin and Kadota 1972). Using
Rasumov's method, Russian hydrobiologists published during the 1950s to the
1970s numerous papers on the density and spatial distribution of bacterioplankton and its production, the latter being estimated after the method
devised by Ivanov (1955) and based on the use of Rasumov's method.