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Interactive Effects Of Timing, Intensity And Duration Of Experimental Shading On Amphibolis Griffithii, Paul Lavery, Kathryn Mcmahon, Michael Mulligan, Andrew Tennyson

Kathryn McMahon

The responses of the seagrass Amphibolis griffithii to different experimental shading conditions were examined by characterising biomass, morphological and physiological features. In an in situ experiment, the intensity (ambient, moderate shading [13 to 19% of ambient] and high shading [5 to 11% of ambient]), duration (3, 6, 9 mo) and timing (post-summer, post-winter) of light reductions were manipulated. We observed interactive effects of all 3 factors, the most notable being with timing. When moderate shading was imposed at the end of summer there was a 57% loss of leaf biomass and 67% loss of rhizome carbohydrates within 3 mo. The …