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 the laboratory using waterlogged and reflooded intertidal sediments from Marennes-Oleron Bay, France. The fluff deposit was enriched in NH4+ compared to underlying sediments, and promoted changes of the sediment pH, E-h, C:N ratio, C:chl a ratio and the NH4+ efflux to overlying water. Statistical analysis showed that pore water NH4+ concentrations were strongly influenced by interactions between fluff, drying, depth and bioturbation. The fluff deposit resulted in anoxia in the top sediments and moved the nitrification zone to surface layers in fluff. However, the NH4+ enrichment in fluff did not significantly change actual nitrification rates (range 0-1 mmol m(-2) d(-1)) or potential nitrification rates (range 3-11 mmol NO3- m(-2) d(-1)).