NUTRIENT CONCENTRATION IN TISSUE OF THE MACROALGA ENTEROMORPHA AS A FUNCTION OF NUTRIENT HISTORY - AN EXPERIMENTAL EVALUATION USING FIELD MICROCOSMS

Nutrient enrichment experiments were conducted to assess the relations hip between nutrient concentration in the tissue of the macroalga Ente romorpha sp. and nutrient history. Experimental units were outdoor mic rocosms containing mixed assemblages of algae representative of commun ities commonly found in coastal lagoons of southern California, USA. W e determined the relationship between nutrient supply rates (nitrogen and phosphorus as well as N:P ratio), water-column nutrient concentrat ions, and macroalgal tissue nutrient concentration in samples taken fr om experimental microcosms containing macroalgae, phytoplankton, and c yanobacterial mats, and treated with 13 combinations of nitrogen and p hosphorus addition. The regression coefficients that described the fit of the relationships between tissue P and both P supply rate and wate r-column concentration were greater than for the same relationships f or N. The relationship between tissue nutrients and either measure of nutrient history (water-column concentration or supply rate) was most useful when the nutrient was not limiting.