Response of benthic and planktonic algal biomass to experimental water-level manipulation in a prairie lakeshore wetland
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- Robinson, G.G.C., Gurney, S.E. & Goldsborough, L.G. Wetlands (1997) 17: 167. doi:10.1007/BF03161407
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The quantitative contribution of benthic (periphytic) and planktonic algae to primary production in prairie wetlands is largely unknown, as is their response to the fluctuations in water level that characterize such systems. We measured the biomass (chlorophyll-a m−2 of wetland area) of phytoplankton, epipelon, epiphyton, and metaphyton in Delta Marsh, Manitoba as part of a five-year study in which diked, drawn down cells were reflooded to the normal level of the wetland, or to a depth 30 cm or 60 cm deeper. Our objective was to investigate the effects of flooding depth on algal biomass and the relative contributions by each of the four algal assemblages. Floating metaphyton mats flourished in all cells after flooding, contributing about 87% of total algal biomass. Epiphytes contributed 11% of biomass, and epipelon and phytoplankton each contributed 1%. Emergent macrophyte density was reduced by flooding, leading to increases in open water area. The wetland cells changed gradually over the study period from an early “open wetland” to a “sheltered wetland.” In late stages of the study, phytoplankton became more abundant as the cells proceeded to a “lake wetland” state.
Key Wordsalgae periphyton epipelon epiphyton metaphyton phytoplankton biomass production marsh wetland prairie Canada
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