USE OF ALGAL ASSAYS
IN STUDYING
EUTROPHICATION PROBLEMS
THOMAS E. MALONEY et al
National Eutrophication Research Program, National Environmental
Research Centre, 200 S.W. 35th Street, Corvallis, Oregon, U.S.A.
INTRODUCTION
With the surge of interest-in the growing problem of eutrophication in the United
States and throughout the world, the Joint Industry/Government Task Force on
Eutrophication recognized that acceptable standardized algal growth tests must be
developed as a tool to cope with the problem. While many investigators have improvised
algal assays to meet thfcir specific needs, they offer no basis for comparison of acceptably
reproducible results among laboratories or among samples obtained from different
geographic areas.
As a starting point in the standardization of an algal assay, a tentative procedure was
prepared by the National Eutrophication Research Program. In March 1968 a group of
scientists having a fundamental knowledge of algal physiology and algal growth responses,
and having experience with algal assays of various types was brought together to carefully
scrutinize the procedure, and recommend additions, deletions, and changes. The group
recognized three fundamentally different procedures; a static "bottle-test", a continuous
flow-chemostat test, and an in situ test. The three types of tests were described in a
document entitled "Provisional Algal Assay Procedure" (1) (PAAP) which was published
in February, 1969. It was fully recognized that the PAAP was tentative and that a great
deal of research would be necessary to sharpen each of the three procedures and to
compare performance among the three tests.
Shortly after publication of the PAAP, a group of government, university and
industrial laboratories undertook a comprehensive research program to improve and
evaluate it. The first phase was concerned with comparing the Bottle Test with the
Continuous Flow-Chemostat Test for assaying the algal growth-nutrient concentration
relationships in natural and enriched waters. Each laboratory followed the same research
plan for the evaluation using algal test species from a common source. A typical protocol
for the evaluation is shown in Table 1. When specific problems were recognized, certain
laboratories were assigned to investigate them after agreement was reached on the
research plan to be followed. Some of the problems which were investigated were (1)
formulation of a culture medium to minimize nutrient carry over in the inoculum; (2)
determination of the optimum age of inoculum; (3) determination of the optimum
sample surface area to volume of test container; (4) determination of the optimum
physical conditions, such as light intensity and temperature for incubation; (5)
determination of methods to control pH to ensure the availability of carbon dioxide; (6)
determination and evaluation of best method(s) to measure algal biomass; and (7)
determination of the best method(s) for sample preparation.
After most of the problems had been reconciled, interlaboratory precision tests were
undertaken to evaluate the capabilities of the Bottle Test. Eight laboratories participated
with each laboratory using an algal test species and chemical reagents from a common
source. Each laboratory used an identical protocol including the same size samples and
205
IN STUDYING
EUTROPHICATION PROBLEMS
THOMAS E. MALONEY et al
National Eutrophication Research Program, National Environmental
Research Centre, 200 S.W. 35th Street, Corvallis, Oregon, U.S.A.
INTRODUCTION
With the surge of interest-in the growing problem of eutrophication in the United
States and throughout the world, the Joint Industry/Government Task Force on
Eutrophication recognized that acceptable standardized algal growth tests must be
developed as a tool to cope with the problem. While many investigators have improvised
algal assays to meet thfcir specific needs, they offer no basis for comparison of acceptably
reproducible results among laboratories or among samples obtained from different
geographic areas.
As a starting point in the standardization of an algal assay, a tentative procedure was
prepared by the National Eutrophication Research Program. In March 1968 a group of
scientists having a fundamental knowledge of algal physiology and algal growth responses,
and having experience with algal assays of various types was brought together to carefully
scrutinize the procedure, and recommend additions, deletions, and changes. The group
recognized three fundamentally different procedures; a static "bottle-test", a continuous
flow-chemostat test, and an in situ test. The three types of tests were described in a
document entitled "Provisional Algal Assay Procedure" (1) (PAAP) which was published
in February, 1969. It was fully recognized that the PAAP was tentative and that a great
deal of research would be necessary to sharpen each of the three procedures and to
compare performance among the three tests.
Shortly after publication of the PAAP, a group of government, university and
industrial laboratories undertook a comprehensive research program to improve and
evaluate it. The first phase was concerned with comparing the Bottle Test with the
Continuous Flow-Chemostat Test for assaying the algal growth-nutrient concentration
relationships in natural and enriched waters. Each laboratory followed the same research
plan for the evaluation using algal test species from a common source. A typical protocol
for the evaluation is shown in Table 1. When specific problems were recognized, certain
laboratories were assigned to investigate them after agreement was reached on the
research plan to be followed. Some of the problems which were investigated were (1)
formulation of a culture medium to minimize nutrient carry over in the inoculum; (2)
determination of the optimum age of inoculum; (3) determination of the optimum
sample surface area to volume of test container; (4) determination of the optimum
physical conditions, such as light intensity and temperature for incubation; (5)
determination of methods to control pH to ensure the availability of carbon dioxide; (6)
determination and evaluation of best method(s) to measure algal biomass; and (7)
determination of the best method(s) for sample preparation.
After most of the problems had been reconciled, interlaboratory precision tests were
undertaken to evaluate the capabilities of the Bottle Test. Eight laboratories participated
with each laboratory using an algal test species and chemical reagents from a common
source. Each laboratory used an identical protocol including the same size samples and
205