The seasonal biomass and productivity of the submerged macrophytes in a polluted Wisconsin stream

SUMMARY 1. We measured biomass and light/dark bottle productivity of macrophytes in a Wisconsin stream throughout one growing season. Except for a brief period in early spring when a Cladophora glomerata‐filamentous algal community was dominant, Potamogeton pectinatus was the dominant macrophyte species in Badfish Creek. 2. Maximum community biomass was 710 g DW m−2, with a maximum above ground biomass of 620 g DW m−2 and a maximum below ground biomass of 120 g DW m−2. Annual productivity was estimated at 1435 g DW m−2 year−1, with a calculated P/B of 2.01. 3. In situ net production averaged 2.83g C g AFDW−1 h−1 Net positive carbon gain by the P. pectinatus community occurred when water temperatures were above 15°C, and daylength at least 12h. This is correlated to the onset of tuber germination in spring, and the point of maximal biomass decline in autumn.