Alteration of phytoplankton phosphorus status during enrichment experiments: implications for interpreting nutrient enrichment bioassay results

James J. Elser, Bruce L. Kimmel

Research output: Contribution to journalArticle

32 Scopus citations


We compared the results of phosphorus-enrichment bioassay experiments with alkaline phosphatase activity (APA) assays as indicators of phosphorus (P) limitation of in situ phytoplankton growth. In 4-d experiments, phytoplankton APA decreased or remained unchanged in P-enriched samples, but increased in unenriched samples, indicating a rapid alteration of the P status of the unenriched algae during the experimental incubations. In direct comparisons of enrichment bioassays and APA assays of reservoir phytoplankton samples, the results of the two methods corresponded in general, although contradictory results were not uncommon. Our data support the conclusion that enrichment experiments can indicate the potential for nutrient limitation of algal growth in the absence of other limiting factors, but do not necessarily demonstrate the occurrence of in situ nutrient limitation of phytoplankton production.

Original languageEnglish (US)
Pages (from-to)217-222
Number of pages6
Issue number3
StatePublished - Mar 1 1986



  • alkaline phosphatase assay
  • limiting factors
  • nutrient enrichment bioassay
  • phytoplankton production

ASJC Scopus subject areas

  • Aquatic Science

Cite this