Application of the Algal Assay Procedure-Bottle Test to pond limnology : an improved pretreatment method

Abstract

The wide diversity of farm ponds makes categorizing and making regional comparisons of these aquatic systems a difficult task. Before meaningful regional classifications can be identified, a large and diverse data set must be analyzed. To facilitate this task, a method of measuring basic productivity which requires a minimal amount of field and laboratory effort is needed. The Algal Assay Procedure-Bottle Test, which is designed to measure algal growth potential (AGP), was developed to be such a method. However, variability in the AGP, resulting from incomplete and inconsistent release of organically bound nutrients to bioavailable forms by the currently accepted pretreatment method (autoclaving), makes it difficult to compare assay results from samples taken at different stages of growth of the algal populations. Several alternative approaches to assay pretreatment were investigated in this study. The experimental treatments included exposure to short-wave ultraviolet radiation, and the addition of oxidizers (sulfuric acid or hydrogen peroxide) in conjunction with autoclaving and/or ultraviolet light exposure. Most of the treatments either did not significantly improve nutrient release or algal growth compared to autoclaving alone, or were toxic or inhibitory to algal growth. Of all the pretreatment methods investigated, the addition of hydrogen peroxide followed by UV light exposure and autoclaving showed the most promise as a means of obtaining the algal growth potential based on all nutrients present..