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The effects of iron and manganese on diatom colonization in a Vermont stream
- WELLNITZ, T.A., SHELDON, S.P.
- Freshwater biology 1995 v.34 no.3 pp. 465-470
- Bacillariophyta, bacteria, iron, iron oxides, manganese, nutrients, streams, Vermont
- 1. Neutral streams with elevated concentrations of iron and manganese can develop blooms of ferromanganese‐depositing bacteria within oxide deposition zones. Algal abundance declines within these blooms. An in situ experiment was conducted in a Vermont stream to assess the importance of increased concentrations of iron and manganese, without the confounding effects of ferromanganese‐depositing bacteria, on limiting diatom colonization. 2. Diatom abundance in treatments receiving iron increased over time, but densities were lower by a factor of ten or more compared with either control or manganese treatments. These results indicate that the presence of ferromanganese‐depositing bacteria is not necessary for lowering algal abundance. 3. We speculate that ferromanganese‐depositing bacteria may thrive in iron oxide deposition zones, in part because iron oxides help displace periphytic algae which may be superior competitors for space and/or limiting nutrients.