A Batch Algal Bioassay Procedure
For Assessing Potential Eutrophication
DONALD R. SCHMOEGER, Senior Microbiologist
Nestle Company
Marysville, Ohio 43040
NELSON L. NEMEROW, Professor
Department of Civil Engineering
Syracuse University
Syracuse, New York 13210
EMIL J. GENETELLI, Professor
Department of Environmental Sciences
Rutgers University
New Brunswick, New Jersey 08903
INTRODUCTION
Eutrophication or enrichment of our waterways, hastened by man's cultural
advancement, has resulted in one of today's most urgent ecological problems. Before the
turn of the century, the magnitude of the urban population and respective waste was
diminutive and well dispersed. Today, the majority of the people are concentrated in
smaller industrialized land areas frequently situated near major bodies of water. The result
is that enormous volumes of both domestic and industrial wastes are continually being
discharged into receiving waters with little hope of natural assimilation. The buildup of
these organic materials and fertilizing nutrients generally initiates the rapid and abundant
growth of obnoxious algae and other vegetation commonly referred to as a "bloom." The
appearance of a bloom represents the focal point for a multitude of problems ranging from
aesthetic appeal to public health.
It was customary at one time to tackle problems of this nature only through chemical
measurements of growth fertilizing nutrients; however, chemical methods, regardless of
the degree of reliable quantification, cannot accurately assess the state of eutrophication.
Only through the use of indicator organisms — flora and fauna alike — can we provide ipso
facto an immediate and meaningful signal of growing enrichment.
In recent years, the environmentally controlled in vitro bioassay has played a popular
role in nutrient assessment studies. A "bottle" or "tube" is usually employed where a given
algal culture, grown under a defined set of parameters, is assayed for its standing crop
and/ or rate of growth. Although this technique is artificial in the sense that a body of water
is in continuous motion and therefore constant change, one is yet able through a carefully
designed sampling program, proper controls, and repetition of samples to accurately
evaluate the biologically available nutrient levels and limiting growth factors and thus
determine a meaningful eutrophication profile. It is this information that is vitally needed in
order to combat the "green tide" and eutrophic inflation.
The E.P.A. — National Eutrophication Research Program set forth procedures
describing a batch bioassay or bottle test (1, 2). Although several methods for monitoring
algal growth were proposed, one — a photometric — seemed to offer the best opportunities
for assaying all concentrations quickly, in a sterile system with high reproducibility and
precision. It is the purpose of this study to evaluate the batch bioassay methodology
engaging spectrophotometric techniques in order to establish without compromising
required precision and sensitivity — a simiplified, conventient system aimed for widespread
use by technician level personnel.
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