Recycling of Nutrients in an Enclosed Aquatic Community of Decomposing Macrophytes (Myriophyllum spicatum)

Abstract

A 0.5 m2 area of littoral zone in an eutrophic reservoir dominated by the aquatic vascular plant M. spicatum L. was enclosed to study, in situ, the release of N and P compounds as the enclosed plant community decomposed. Decomposition was complete in about 50 d [day]. Fixed N appeared mainly as NH3 at a maximum rate of 380 .mu.g 1-1 d-1. P was mobilized mainly as PO4- at a maximum rate of 34 .mu.g 1-1 d-1 and also as soluble organic-P. Aquatic macrophytes accounted for only 3-4% of the regenerated N but for 40-44% of the regenerated P recycled by the enclosed system. Blue-green algae and the mud surface accounted for the balance of the regenerated N and P. Total suspended bacterial biomass represented an average of 10% of the total organic N and P pool of the water column. The role of aquatic macrophytes, blue-green algae and mud surface is discussed in terms of the recycling of N and P.