Ecosystem metabolism in a temporary Mediterranean marsh (Doñana National Park, SW Spain)
- 1Freshwater Biological Laboratory, University of Copenhagen, 51 Helsingørsgrade, 3400 Hillerød, Denmark
- 2Departamento de Ecología, Universidad Autónoma, 28049 Madrid, Spain
- 3IMEDEA (CSIC-UIB), Grupo de Oceanografía Interdisciplinar, Instituto Mediterráneo de Estudios Avanzados, C/Miquel Marqués, 21, 07190 Esporles, Illes Balears, Spain
- 4UWA Oceans Institute, University of Western Australia, 35 Stirling Highway, Crawley 6009, Australia
- 5Station Biologique de la Tour du Valat, 13200 Le Sambuc, France
- *present address: AquaSim, Slagslunde Bygade 37, 3660 Stenløse, Denmark
Abstract. The metabolic balance of the open waters supporting submerged macrophytes of the Doñana marsh (SW Spain) was investigated in spring, when community production is highest. The marsh community (benthic + pelagic) was net autotrophic with net community production rates averaging 0.61 g C m−2 d−1, and gross production rates exceeding community respiration rates by, on average, 43%. Net community production increased greatly with increasing irradiance, with the threshold irradiance for communities to become net autotrophic ranging from 42 to 255 μE m−2 s−1, with net heterotrophic at lower irradiance. Examination of the contributions of the benthic and the pelagic compartments showed the pelagic compartment to be strongly heterotrophic (average P/R ratio = 0.27), indicating that the metabolism of the pelagic compartment is highly subsidised by excess organic carbon produced in the strongly autotrophic benthic compartment (average P/R = 1.58).