The disparity between the relative proportions of nutrients made available by fish and the proportions of nutrients assimilated by plants resulted in differential rates of change in concentration for various nutrients (Fig. 3). Relative changes in concentration (percent change from initial concentration) generally followed the trend: Zn>N≈Mg>K>Ca≈P>Cu>Fe>Mn, although some variation from this trend was observed. Nutrient reduction greater than 100% indicates that the nutrient was supplemented during the trial.