The Interrelation of Carbon and
Phosphorus in Regulating Heterotrophic and
Autotrophic Populations in an
Aquatic Ecosystem*
DONALD L. BROCKWAY, Biologist
PAT C. KERR, Biologist
DORIS F. PARIS, Chemist
National Pollutants Fate Research Program
USDI - FWQA
Southwest Water Laboratory
Athens, Georgia
*This paper was presented as three papers at the Industrial Waste Conference. It is
herein published as one paper. The titles of the three papers are as follows: "Role of
Carbon in Regulating the Growth of Mixed Heterotrophic and Autotrophic
Populations in an Aquatic System." "The Role of Phosphorus in Regulating the
Growth of a Mixed Heterotrophic and Autotrophic Population in an Aquatic
System." "The Relationship Between Carbon and Phosphorus in a Mixed Heterotrophic and Autotrophic Population in an Aquatic System."
INTRODUCTION
The increasing demands to control water pollution, to curb eutrophication, and
to develop rational predictive models for water quality management require a fuller
quantitative and qualitative understanding of the fundamental biological, chemical,
and physical reactions and interactions occurring in natural waters.
The research described in this paper is a portion of the work being done by the
National Pollutants Fate Research Program at the Southeast Water Laboratory
designed to study the cycling of carbon, phosphorus, and nitrogen through aquatic
ecosystems.
Algal blooms frequently accompany cultural enrichment of waters. Increased
amounts of available nitrogen and phosphorus have been suggested as the cause of
these blooms. Although the importance of carbon in regulating algal growth has long
been known, it was largely overlooked until recently (1). Increased supplies of
carbon (as well as nitrogen and phosphorus) had to be available to support the
increased algal growth associated with enriched waters.
The relative chemical composition of living organisms demonstrates the
importance of carbon as a nutrient. Carbon accounts for 50-77 per cent of the dry
weight of algae and 45-55 per cent of the dry weight of bacteria.
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