metabolic balance of the open waters supporting submerged macrophytes of the Donana 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 mu E 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).
Geertz-Hansen, O., Montes, C., Duarte, C. M., Sand-Jensen, K., Marbá, N., & Grillas, P. (2011). Ecosystem metabolism in a temporary Mediterranean marsh (Doñana National Park, SW Spain). Biogeosciences, 8(4), 963–971. https://doi.org/10.5194/bg-8-963-2011