Nutrient and Sediment Retention in a Temperate Marsh Ecosystem

Abstract

AbstractThe Wye marsh, an undeveloped wetland of 639.9 ha, serves as a receiving water for a 19,600 ha agricultural watershed before discharging into the Great Lakes. Seasonal and diel changes in limnological variables, most notably nitrogen, phosphorus, silica and turbidity, have been examined in the Wye river, marsh and discharge waters over an 11‐month period and related to the composition of marsh sediments. Retention rates of the marsh ecosystem for incoming nutrients and suspended solids have been estimated by calculations of mean monthly inflow to outflow ratios using the levels of these factors in the Wye River and the marsh discharge. Calculated mean monthly retention rates of the marsh for incoming nutrients is estimated at no less than 61% for nitrogen‐N, 36% for total phosphate, and 14% for soluble silica during the ice‐free period. Based on observed turbidity levels, the retention of incoming suspended solids is estimated at 65% for the same period. The Wye marsh is a substantial sump for inorganic and organic materials which are retained within the water column, biomass and unconsolidated sediments.