Formal discussion by L.M. Klashman
A major limitation of a flask assay procedure, or as the authors refer to it a "Bottle Test" assay, is
that at best the method represents simple ecosystems rather than the complex dynamic system of
nature where each species of algae exists as a member of a community. Laboratory testing of a single
species rarely takes into account such important biological variables as interspecific competition and
nutrient and energy flow through the ecosystem.
Yet, despite these disadvantages, attention is drawn to Table 3 and the remarkable correlation
between the Algal Dry Weight vs. Phosphorus Concentration and the in situ cells/ml vs. Phosphorus
Concentration. After the initial addition of Phosphorus, the in situ algal cell concentration and the
Bottle Test data show identical proportional increases.
This data supplements the data of Skulberg (using Selenastrum Capricornutum) presented at the
3rd International Conference in Munich.
(Advances in Water Pollution Research - 3rd International Conference - Munich, Germany,
September, 1966).
I would also like to call attention to two'columns; the +N & P & C columns on Table 4.
Table 4 shows the effects of Nutrient Additions to Lake Water on Algal growth. It appears that a
comparison of these two columns indicate that in 50% of the lakes samples and reported on in Table
4, Algal growth benefited from the addition of Carbon in addition to the nitrogen and phosphorus.
This important fact should not be overlooked in our hydrobiotic evaluations.
Finally, I note that the authors used a multiple regression analysis using the various chemical
parameters as the independent variable and the maximum algal yield of the bottle test as the
dependent variable.
I suggest it might be interesting to also treat Nitrogen, Phosphorus and Carbon as dependent
variables. Then, by proper arrangement of the data into a Latin Square an analysis of variance may
show significant interaction terms, (between C, P & N)
This paper shows that when the Bottle Technique is practiced with care, the use of Algal cultures
in assaying the effects of pollution on receiving waters will give valuable results and such results may
be safely used in conjunction with other chemical or limnological studies in establishing criteria for
waste treatment.
Neal E. Armstrong, USA.
Is the United States Environmental Protection Agency Eutrophication Program developing an algal
bioassay for estuaries and coastal waters and, if so, will light be included as a limiting factor?
Reply
Yes, we are presently working with several marine unicellular algae to adapt the procedure for use
in estuaries and coastal waters. We are considering light as a limiting factor as well as temperature and
salinity.
M. Halmann, Israel
What are the relative advantages and disadvantages of the "bottle tests" of algal assays using either
a pure strain test organism, or unfiltered lake-water in situ, testing the growth of the natural
communities of micro-organism?
Reply
In using a pure strain test organism in a "bottle test" algal assay the assay can be standardized for
physical conditions such as temperature and light intensity. This permits comparison of results of
assays conducted on waters collected in different geographic areas, and between laboratories. The in
situ assay has the advantage of determining the growth responses of algae that are indigenous to the
water being tested under the particular physical conditions existing at the time of assay. It has been
found, however, that unless the in situ assay is relatively short term, there is often a tremendous
change in species composition during the assay.
J.P. Bruce, Canada
In eutrophication control practice the important question is which of the essential nutrients is
most readily controllable by man? In those few cases when N & C were found limiting, could P be
made the limiting nutrient by a P control program?
Reply
Most certainly.
215
A major limitation of a flask assay procedure, or as the authors refer to it a "Bottle Test" assay, is
that at best the method represents simple ecosystems rather than the complex dynamic system of
nature where each species of algae exists as a member of a community. Laboratory testing of a single
species rarely takes into account such important biological variables as interspecific competition and
nutrient and energy flow through the ecosystem.
Yet, despite these disadvantages, attention is drawn to Table 3 and the remarkable correlation
between the Algal Dry Weight vs. Phosphorus Concentration and the in situ cells/ml vs. Phosphorus
Concentration. After the initial addition of Phosphorus, the in situ algal cell concentration and the
Bottle Test data show identical proportional increases.
This data supplements the data of Skulberg (using Selenastrum Capricornutum) presented at the
3rd International Conference in Munich.
(Advances in Water Pollution Research - 3rd International Conference - Munich, Germany,
September, 1966).
I would also like to call attention to two'columns; the +N & P & C columns on Table 4.
Table 4 shows the effects of Nutrient Additions to Lake Water on Algal growth. It appears that a
comparison of these two columns indicate that in 50% of the lakes samples and reported on in Table
4, Algal growth benefited from the addition of Carbon in addition to the nitrogen and phosphorus.
This important fact should not be overlooked in our hydrobiotic evaluations.
Finally, I note that the authors used a multiple regression analysis using the various chemical
parameters as the independent variable and the maximum algal yield of the bottle test as the
dependent variable.
I suggest it might be interesting to also treat Nitrogen, Phosphorus and Carbon as dependent
variables. Then, by proper arrangement of the data into a Latin Square an analysis of variance may
show significant interaction terms, (between C, P & N)
This paper shows that when the Bottle Technique is practiced with care, the use of Algal cultures
in assaying the effects of pollution on receiving waters will give valuable results and such results may
be safely used in conjunction with other chemical or limnological studies in establishing criteria for
waste treatment.
Neal E. Armstrong, USA.
Is the United States Environmental Protection Agency Eutrophication Program developing an algal
bioassay for estuaries and coastal waters and, if so, will light be included as a limiting factor?
Reply
Yes, we are presently working with several marine unicellular algae to adapt the procedure for use
in estuaries and coastal waters. We are considering light as a limiting factor as well as temperature and
salinity.
M. Halmann, Israel
What are the relative advantages and disadvantages of the "bottle tests" of algal assays using either
a pure strain test organism, or unfiltered lake-water in situ, testing the growth of the natural
communities of micro-organism?
Reply
In using a pure strain test organism in a "bottle test" algal assay the assay can be standardized for
physical conditions such as temperature and light intensity. This permits comparison of results of
assays conducted on waters collected in different geographic areas, and between laboratories. The in
situ assay has the advantage of determining the growth responses of algae that are indigenous to the
water being tested under the particular physical conditions existing at the time of assay. It has been
found, however, that unless the in situ assay is relatively short term, there is often a tremendous
change in species composition during the assay.
J.P. Bruce, Canada
In eutrophication control practice the important question is which of the essential nutrients is
most readily controllable by man? In those few cases when N & C were found limiting, could P be
made the limiting nutrient by a P control program?
Reply
Most certainly.
215