Fluff deposition on intertidal sediments: effects on benthic biota, ammonium fluxes and nitrification rates

摘要

The effects of fluff deposit on benthic biota,NH4 + fluxes and nitrification was studied in thelaboratory using waterlogged and reflooded intertidal sediments fromMarennes-Oléron Bay, France. The fluff deposit was enriched inNH4 + compared to underlying sediments, and promotedchanges of the sediment pH, Eh, C:N ratio, C:chla ratio and the NH4 + efflux tooverlying water. Statistical analysis showed that pore waterNH4 + concentrations were strongly influenced byinteractions between fluff, drying, depth and bioturbation. The fluff depositresulted in anoxia in the top sediments and moved the nitrification zone tosurface layers in fluff. However, the NH4 + enrichment influff did not significantly change actual nitrification rates (range 0–1mmol m−2 d−1) or potentialnitrification rates (range 3–11 mmolNO3 − m−2d−1).