Study of the Dynamics of Phosphorus
257
being among the most important characteristics of aquatK: environments
(Phillips 1964). Practically any hydrobiological or oceanographic survey of
marine or freshwater basins traditionally is accompanied by detailed analyses
of ambiental concentrations of reactive P04-P; but while they make such
surveys and produce thousands of these analyses, most hydrochemists and
hydro biologists do not realize perhaps that they may be uf unly minot
scientific significance. Indeed, the data on the absolute P04P concentration in
water, especially in the productive photic layers, where phosphorus is deficient,
carry little or no useful information concerning biological productivity.
Its measured standing stock is only a momentary balance value determined
by the ratio of the reciprocal dynamic process of its consumption, regeneration, and external import-export. The absolute concentrations of P04P in
the productive euphotic zone most often are of little scientific significance
because everything depends upon the velocity of its flows. If these flows in an
aquatic biotopes are fast, a top possible level of primary production - up to
3 g m- 2 day-l - may be supported there for several months, even when the P04P
ambient concentration in water during the whole period is approaching analytical zero. This can happen, because the turnover time of phosphorus in
natural aquatic environments may be as short as a few minutes. I have
observed this situation in the lagoons of Comacchio in northern Italy (Fig.
5.13) and in the Brasilian flood plain lakes. In the upwelling areas outside the
"blue pools", where the bloom of phytoplankton reaches its maximum force
and where the thermocline is also formed, the concentration of reactive phosphate is very often is at its limiting boundary of O.1-0.2Ilmoll-1 while the
primary production may be over 2gcm- 3 day-l(Sorokin 1985); the opposite
situation may be also observed when primary production is permanently low
due to rather high phosphate content in the euphotic zone (southeastern
Pacific). Both cases are perfectly explainable by the difference in the dynamic
rates of phosphorus turnover, which was measured with the use of 32p In the
first case, the high input flows are provided by its hydrodynamic vertical transport via a shallow thermocline and due to its rapid regeneration by the powerful cohorts of euphausiids, anchovies, and sea birds. In the case of the eastern
Pacific with its stable mature pelagic ecosystem, the rather abundant population of zooplankton grazers there totally consume all the diurnal production
of phytoplankton, thus keeping its biomass at a low level, while actively regenerating the nutrients. The latter accumulate in the euphotic zone, where they
are underexploited.
The inverse correlation between the primary production and P04P
content in water of the euphotic zone is a much more common situation in
most marine and freshwater basins especially during the periods of established
vertical stratification than the positive one (Figs 5.14 and 5.15), and it is quite
understandable. By restricted input flows of phosphate into the pelagic communities of euphotic zones, the phytoplankton and bacterioplankton inhabiting its mixed upper layer have also consumed all its stock down to analytical
zero, while their production still remains high, being supported by rapid P04-
257
being among the most important characteristics of aquatK: environments
(Phillips 1964). Practically any hydrobiological or oceanographic survey of
marine or freshwater basins traditionally is accompanied by detailed analyses
of ambiental concentrations of reactive P04-P; but while they make such
surveys and produce thousands of these analyses, most hydrochemists and
hydro biologists do not realize perhaps that they may be uf unly minot
scientific significance. Indeed, the data on the absolute P04P concentration in
water, especially in the productive photic layers, where phosphorus is deficient,
carry little or no useful information concerning biological productivity.
Its measured standing stock is only a momentary balance value determined
by the ratio of the reciprocal dynamic process of its consumption, regeneration, and external import-export. The absolute concentrations of P04P in
the productive euphotic zone most often are of little scientific significance
because everything depends upon the velocity of its flows. If these flows in an
aquatic biotopes are fast, a top possible level of primary production - up to
3 g m- 2 day-l - may be supported there for several months, even when the P04P
ambient concentration in water during the whole period is approaching analytical zero. This can happen, because the turnover time of phosphorus in
natural aquatic environments may be as short as a few minutes. I have
observed this situation in the lagoons of Comacchio in northern Italy (Fig.
5.13) and in the Brasilian flood plain lakes. In the upwelling areas outside the
"blue pools", where the bloom of phytoplankton reaches its maximum force
and where the thermocline is also formed, the concentration of reactive phosphate is very often is at its limiting boundary of O.1-0.2Ilmoll-1 while the
primary production may be over 2gcm- 3 day-l(Sorokin 1985); the opposite
situation may be also observed when primary production is permanently low
due to rather high phosphate content in the euphotic zone (southeastern
Pacific). Both cases are perfectly explainable by the difference in the dynamic
rates of phosphorus turnover, which was measured with the use of 32p In the
first case, the high input flows are provided by its hydrodynamic vertical transport via a shallow thermocline and due to its rapid regeneration by the powerful cohorts of euphausiids, anchovies, and sea birds. In the case of the eastern
Pacific with its stable mature pelagic ecosystem, the rather abundant population of zooplankton grazers there totally consume all the diurnal production
of phytoplankton, thus keeping its biomass at a low level, while actively regenerating the nutrients. The latter accumulate in the euphotic zone, where they
are underexploited.
The inverse correlation between the primary production and P04P
content in water of the euphotic zone is a much more common situation in
most marine and freshwater basins especially during the periods of established
vertical stratification than the positive one (Figs 5.14 and 5.15), and it is quite
understandable. By restricted input flows of phosphate into the pelagic communities of euphotic zones, the phytoplankton and bacterioplankton inhabiting its mixed upper layer have also consumed all its stock down to analytical
zero, while their production still remains high, being supported by rapid P04-