Phosphorus limitation of Cymodocea nodosa growth

Experimental nutrient (N, P, and N+P) additions to shallow (ca. 1 m)Cymodocea nodosa (Ucria) Aschers. stands growing in patches and in a continuous meadow in a Mediterranean Bay (Alfacs Bay, NE Spain) in 1988 demonstrated mid-summer growth to be strongly P-limited, as suggested by the high N:P ratios (>35) in unmanipulated plants. P additions resulted in increased leaf P content, reduced N:P ratios, and enhanced shoot growth and turnover in both populations. These effects promoted in turn a stand response, leading to increased biomass and, therefore, increased areal productivity in the plots receiving P. The stand response was largely attributable to a doubling of shoot density, indicating enhanced rhizome growth and branching.