2 The Radiocarbon Method to Estimate Primary
Production in Aquatic Environments
2.1 Introduction
The term primary production means the photosynthetic production of new
organic matter from carbon of CO2 and hydrocarbonates by aquatic plants
(Winberg 1960). Primary production is the basic source of external energy
input into most aquatic ecosystems. Therefore, any attempt to estimate or
model their energy balances first needs adequate evaluation of the size of
primary production. The parameters of primary production per day and per
whole season are a fundamental characteristic of the trophical status of a given
water body and its ecological state (Margalef 1965). In fact, measurements of
primary production have become a basic analysis to any serious hydrobiological investigation to obtain general characteristics of aquatic ecosystems and
evaluate the degree of their anthropogenic transformation. Special attention
was paid to estimating primary production in the oceans. These data are
needed to calculate the carbon budget of the Earth in face of the greenhouse
phenomenon. Therefore the development of efficient, rapid, and adequate
methods of primary production measurement in aquatic environments was,
and in some sense still remains, one of the key problems in hydrobiology.
Primary production in aquatic environments is created by various components of free-living and symbiotic algal and microbial associations, starting
from anaerobic purple bacteria, bacterial sized pico- and nanocyanobacteria,
planktonic, nano- and microalgae, microphytobentic and periphytonic associations, benthic and pelagic (floating) macrophytes, sea grasses, pelagic and
benthic captured (symbiotic) microalgae. Measurement of primary production
by each of these groups of phototrophic organisms obviously needs a specific
methodological approach. During the long practice of hydro biological research
since the late 1920s, several methodological approaches have been tested and
employed to estimate the in situ rates of primary production in pelagic and
benthic biotopes. Methods thus used were based on measurements of oxygen,
CO2, pH, or P04-P fluctuations in enclosures (bottles) or in open water, resulting from the photosynthetic activity of phototrophic communities under
ambient conditions. Of these, the most common was the oxygen dark-light
bottle method, which was commonly in use for measurements of in situ primary
production by pelagic and benthic algae associations until the end of the 1950s,
when it was challenged by the new, more sensitive, radiocarbon method
invented in 1951 by the Dutch botanist E. Steemann Nielsen. This method
soon became the main way of measuring primary production in planktonic
Production in Aquatic Environments
2.1 Introduction
The term primary production means the photosynthetic production of new
organic matter from carbon of CO2 and hydrocarbonates by aquatic plants
(Winberg 1960). Primary production is the basic source of external energy
input into most aquatic ecosystems. Therefore, any attempt to estimate or
model their energy balances first needs adequate evaluation of the size of
primary production. The parameters of primary production per day and per
whole season are a fundamental characteristic of the trophical status of a given
water body and its ecological state (Margalef 1965). In fact, measurements of
primary production have become a basic analysis to any serious hydrobiological investigation to obtain general characteristics of aquatic ecosystems and
evaluate the degree of their anthropogenic transformation. Special attention
was paid to estimating primary production in the oceans. These data are
needed to calculate the carbon budget of the Earth in face of the greenhouse
phenomenon. Therefore the development of efficient, rapid, and adequate
methods of primary production measurement in aquatic environments was,
and in some sense still remains, one of the key problems in hydrobiology.
Primary production in aquatic environments is created by various components of free-living and symbiotic algal and microbial associations, starting
from anaerobic purple bacteria, bacterial sized pico- and nanocyanobacteria,
planktonic, nano- and microalgae, microphytobentic and periphytonic associations, benthic and pelagic (floating) macrophytes, sea grasses, pelagic and
benthic captured (symbiotic) microalgae. Measurement of primary production
by each of these groups of phototrophic organisms obviously needs a specific
methodological approach. During the long practice of hydro biological research
since the late 1920s, several methodological approaches have been tested and
employed to estimate the in situ rates of primary production in pelagic and
benthic biotopes. Methods thus used were based on measurements of oxygen,
CO2, pH, or P04-P fluctuations in enclosures (bottles) or in open water, resulting from the photosynthetic activity of phototrophic communities under
ambient conditions. Of these, the most common was the oxygen dark-light
bottle method, which was commonly in use for measurements of in situ primary
production by pelagic and benthic algae associations until the end of the 1950s,
when it was challenged by the new, more sensitive, radiocarbon method
invented in 1951 by the Dutch botanist E. Steemann Nielsen. This method
soon became the main way of measuring primary production in planktonic