TPM, Stock of Labile Organic Matter, and its Turnover Time
289
tation or periphytonic overgrowth, it is absolutely necessary to make not only
diurnal but also nocturnal catches. In such basins, the biomass is most often
composed largely of demersal forms which in the day time are hiding from
grazing competition in their bottom refuges. Sometimes, the same behavior is
displayed even by typical holoplanktonic forms like Acartia, for example. The
difference between diurnal and nocturnal zooplankton biomass may reach 2
orders of values, to say nothing of the wrong presentation of zooplankton
composition coming from only day time catches.
Concerning the kinds of water bottles which may be used for quantification of zooplankton, it can be models which, being charged, represent completely open plastic cylinders with caps aside. Among such water bottles are,
for example, those by Fridinger or Niskin. The water bottles must be supplied
with a trigger mechanism closing them on indirect command from the surface.
The sample taken with a water bottle is concentrated with the kind of device
shown in Fig. 3.2F. If samples of zooplankton thus collected do not contain
significant amounts of detritus, they may be processed to obtain its biomass
by the wet combustion procedure described above (see Sect. 3.4.1), although
its composition and numerical abundance may be estimated in only a few key
samples. This procedure is much more precise and many times less timeconsuming in comparison with the microscopic counting and sizing procedure.
6.3 Total Plankton Respiration, Stock of Labile Organic
Matter, and its Turnover Time
Total plankton respiration is among the most fundamental parameters characterizing the functional activity of aquatic ecosystems. Its absolute values,
measured by the oxygen bottle method, serve for the characterization of the
trophicallevel of a given water basin even more than the primary production,
because the local plant primary production is not a single and often even
not a main source of energy supporting the functional activity of aquatic
ecosystems. Total plankton respiration reflects the whole process of organic
matter decomposition, independently of its origin. The ratio of total plankton
respiration to primary production is among the most remarkable characteristics of the sources of energy supply of a given ecosystem (autochthonous/
allochthonous) and its successive phases (autotrophic/heterotrophic). These
characteristics may be even more complete when accounting also for bottom
respiration; moreover, its experimental determination creates no problems,
being a rather simple procedure (see below). It is rather curious, but total
plankton respiration (TPM) is not a very popular analysis - at least it is less
popular than, for example, the BOD-5 measurement, whose informative value
is negligible. The latter gives only a comparative but not an absolute value,
while with the use of the same simple technique fundamental absolute
parameters such as the above-mentioned TPM and the stock of labile organic
289
tation or periphytonic overgrowth, it is absolutely necessary to make not only
diurnal but also nocturnal catches. In such basins, the biomass is most often
composed largely of demersal forms which in the day time are hiding from
grazing competition in their bottom refuges. Sometimes, the same behavior is
displayed even by typical holoplanktonic forms like Acartia, for example. The
difference between diurnal and nocturnal zooplankton biomass may reach 2
orders of values, to say nothing of the wrong presentation of zooplankton
composition coming from only day time catches.
Concerning the kinds of water bottles which may be used for quantification of zooplankton, it can be models which, being charged, represent completely open plastic cylinders with caps aside. Among such water bottles are,
for example, those by Fridinger or Niskin. The water bottles must be supplied
with a trigger mechanism closing them on indirect command from the surface.
The sample taken with a water bottle is concentrated with the kind of device
shown in Fig. 3.2F. If samples of zooplankton thus collected do not contain
significant amounts of detritus, they may be processed to obtain its biomass
by the wet combustion procedure described above (see Sect. 3.4.1), although
its composition and numerical abundance may be estimated in only a few key
samples. This procedure is much more precise and many times less timeconsuming in comparison with the microscopic counting and sizing procedure.
6.3 Total Plankton Respiration, Stock of Labile Organic
Matter, and its Turnover Time
Total plankton respiration is among the most fundamental parameters characterizing the functional activity of aquatic ecosystems. Its absolute values,
measured by the oxygen bottle method, serve for the characterization of the
trophicallevel of a given water basin even more than the primary production,
because the local plant primary production is not a single and often even
not a main source of energy supporting the functional activity of aquatic
ecosystems. Total plankton respiration reflects the whole process of organic
matter decomposition, independently of its origin. The ratio of total plankton
respiration to primary production is among the most remarkable characteristics of the sources of energy supply of a given ecosystem (autochthonous/
allochthonous) and its successive phases (autotrophic/heterotrophic). These
characteristics may be even more complete when accounting also for bottom
respiration; moreover, its experimental determination creates no problems,
being a rather simple procedure (see below). It is rather curious, but total
plankton respiration (TPM) is not a very popular analysis - at least it is less
popular than, for example, the BOD-5 measurement, whose informative value
is negligible. The latter gives only a comparative but not an absolute value,
while with the use of the same simple technique fundamental absolute
parameters such as the above-mentioned TPM and the stock of labile organic