Seasonal pattern of Cymodocea nodosa biomass and production in the lagoon of Venice

Primary production and the biomass cycle of a shallow Cymodocea nodosa (Ucria) Ascherson meadow in the lagoon of Venice (Italy-Northern Adriatic) were measured from February 1993 to February 1994. Leaf growth was estimated by the Zieman method; rhizome production was estimated by marking rhizome terminals. All data showed a clear seasonality. In general, maximum growth was reached in July. Leaf production (a maximum of 12.3 g dry weight m −2 day −1 in July) and leaf biomass (a maximum of 810 g dry weight m −2) were much higher than in other Mediterranean localities. Cymodocea nodosa contributes significantly in stabilizing lagoon bottom sediments. The percentage of the belowground fraction of total biomass varied from 85% in winter to 58% in summer, and maximum shoot density was 2302 shoots m −2.