2.5. Statistical analyses
The effect of nutrients under the normal temperature of 27 °C was tested for the algal density, Chl a, AR, and AR% by three-way ANOVA, with the nutrient condition as a fixed effect, tank as a random factor nested in the nutrient treatment, and coral colony as a random factor nested in each tank. The tank effect was dropped from the ANOVA analyses because it was not significant for all the measured parameters. Because the factor of coral colony was significant for algal density and Chl a, the difference between LN and HN was tested by two-tailed Student's t-test for each coral colony.