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The Biology Laboratory conducts Algal Growth Potential and Limiting Nutrient algal assays. Algal Growth Potential (AGP) tests and Limiting-Nutrient assays are the most direct and effective ways to determine the amount of nutrients available to organisms in surface waters, and the eutrophication potential of an aquatic system. These methods provide information on the biologically-available nutrients in the water. Few other laboratories in Florida have the capacity or the staff able to perform these highly useful tests.

Algal Growth Potential (AGP) assays determine the maximum amount of algal growth that the nutrients in a water sample can support. This test provides a better indication of the potential for algal blooms than can be determined by chemical measurement of nutrient concentrations, because all nutrients in the water are not in a form that can be used by algal. Additionally, there may be substances present in the water that inhibit algal growth. In nature, other factors than nutrient availability can limit the growth of algae, such as the amount of light available, water temperature, or the amount of algal being consumed by algae-eating organisms. However, the AGP assay alerts officials to the potential for algal blooms.

Limiting Nutrient (LN) assays determine what nutrient is preventing even more algal growth than is presently possible. All plants, including algal, require various nutrients in different amounts. Whichever of the required nutrients is used up first by the algal prevents further growth regardless of how much of the other nutrients are available. The LN assay helps officials to understand what nutrient is limiting greater algal growth and to regulate discharges of that nutrient to help prevent the occurrence of algal blooms.

Used with taxonomic identification and chlorophyll measurements, these procedures produce a complete picture of the trophic status of a system.

These algal assays require specialized equipment and expertise not found in most laboratories.

The Standard Operating Procedures used in preparation for and conducting Algal Assay and Limiting Nutrient tests can be viewed or downloaded from the Biology Section SOPs.

Last updated: April 03, 2012

  Environmental Assessment and Restoration
Florida DEP Laboratory
2600 Blair Stone Road M.S. 6512
Tallahassee, Florida  32399-2400
850-245-8077 (phone)
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