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Presented at the NABS Annual meeting, Anchorage, Alaska, 2006
in Large River Ecology 1
Sediment respiration in a complex river–floodplain ecosystem: The role of habitat heterogeneity and inundation dynamics
M. Doering, U. Uehlinger, K. Tockner, and T. Ackermann.Department of Limnology, EAWAG/ETH, Switzerland
We studied spatial heterogeneity of respiration in aquatic and terrestrial habitats in a large braided floodplain river (Tagliamento River, NE Italy). In terrestrial habitats, CO2 production was measured with an IRGA. In aquatic habitats, sediments were enclosed in chambers, and respiration was measured as O2 consumption. In addition, we studied the influence of inundation on sediment respiration. To simulate inundation we submersed terrestrial sediments in artificial river water and monitored O2 consumption over six days at three different temperatures (4, 12 and 20 °C). Average daily respiration rates (normalized at 15°C) ranged from 0.3 g C m-2 d-1 in exposed gravel sediments to 5.6 g C m-2 d-1 in riparian forest soils. In parafluvial ponds, respiration rates averaged 0.9 g C m-2 d-1 and in river channels 1.6 g C m-2d -1. In all habitats respiration rates were highly temperature dependent, except in exposed gravel. Inundation led to a decline in respiration of 64 to 90% within 6 hours, except for gravel sediments where respiration increased by 40 to 60%. Our study demonstrates a high spatio–temporal heterogeneity of sediment respiration, mainly as a consequence of habitat heterogeneity and inundation dynamics.
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