Effects of Flooding on Dissolved and Suspended Nutrients in Small Diked Marshes
Flooding ten 5- to 7-ha diked marshes in the Delta Marsh, Manitoba, to about 1 m above natural marsh levels did not increase dissolved or suspended nutrient concentrations in the surface water. Dissolved forms of N and P increased in interstitial water, possibly as a direct or indirect effect of death of emergent macrophytes (e.g. cattail, Typha spp.) and associated changes such as wave action and detritus deposition. Concentrations of suspended N, P and C decreased in surface water as a result of flooding, both in absolute terms and relative to concurrent increases shown by natural marsh controls. Concentrations of major ions (Ca2+, Mg2+, Na+, K+[Formula: see text] and Cl−) did not change in response to flooding, but did vary in time and space. A predicted decrease in the concentrations of major ions in interstitial water due to seepage of dilute surface water into the sediment was not detected.