Decreased nitrogen loading controls summer cyanobacterial blooms without promoting nitrogen‐fixing taxa: Long‐term response of a shallow lake

thesis Decreased nitrogen loading controls summer cyanobacterial blooms without promoting nitrogen‐fixing taxa: Long‐term response of a shallow lake published CHe yes Tom Shatwell author 864240000-0002-4520-7916 Jan Köhler author DEP8022 department The effectiveness of controlling nitrogen (N) to manage lake eutrophication is debated. Long-term, whole-lake case studies are required to determine whether diazotrophic cyanobacteria can fix sufficient N to offset a reduction of N-inputs. We document the recovery of shallow, productive Lake Müggelsee (Germany) over 37 yr (sampling interval 1–2 weeks) during a decrease of N and phosphorus (P) loading of 79% and 69%, respectively. Nitrogen concentrations in the lake responded immediately to loading reduction whereas P concentrations remained elevated for about 20 yr. Total nitrogen (TN) in the lake was always lower than TN in the inflow. Accordingly, estimated denitrification and N-burial rates substantially exceeded N2 fixation rates in the long term. Phosphorus was growth limiting in spring whereas N was clearly limiting in summer due to high sediment P-release. TN : TP ratios, normalized to phytoplankton biovolume by regression, were 25.5 (weight) in spring and 3.3 in summer. During the study period, dissolved inorganic N (DIN) concentrations in summer decreased and the duration of low DIN concentrations increased by ca. 100 d. The biovolume of cyanobacteria and total phytoplankton decreased by 89% and 76%, respectively. The proportion of N2-fixing cyanobacteria during summer decreased from 36% to 14% of the total phytoplankton biovolume. The total concentration of heterocysts and estimated total N2 fixation did not change over time. In the long term, decreasing N-inputs effectively controlled summer cyanobacteria including N2-fixing taxa, which did not compensate for the N-deficit. A P-only control strategy would not have been as successful. Wiley2018 eng Limnology and Oceanography 0024-3590 1939-559010.1002/lno.11002 64S1 yes T. Shatwell and J. Köhler, “Decreased nitrogen loading controls summer cyanobacterial blooms without promoting nitrogen‐fixing taxa: Long‐term response of a shallow lake,” Limnology and Oceanography, vol. 64, no. S1, 2018, doi: <a href="https://doi.org/10.1002/lno.11002">10.1002/lno.11002</a>. Shatwell T, Köhler J. Decreased nitrogen loading controls summer cyanobacterial blooms without promoting nitrogen‐fixing taxa: Long‐term response of a shallow lake. Limnology and Oceanography. 2018;64(S1). doi:<a href="https://doi.org/10.1002/lno.11002">10.1002/lno.11002</a> T. Shatwell, J. Köhler, Limnology and Oceanography 64 (2018).

Shatwell, Tom und Jan Köhler. 2018. Decreased nitrogen loading controls summer cyanobacterial blooms without promoting nitrogen‐fixing taxa: Long‐term response of a shallow lake. Limnology and Oceanography 64, Nr. S1. doi:<a href="https://doi.org/10.1002/lno.11002">10.1002/lno.11002</a>, .

Shatwell, Tom ; Köhler, Jan: Decreased nitrogen loading controls summer cyanobacterial blooms without promoting nitrogen‐fixing taxa: Long‐term response of a shallow lake. In: Limnology and Oceanography Bd. 64. Hoboken, NJ, Wiley (2018), Nr. S1

Shatwell, T., & Köhler, J. (2018). Decreased nitrogen loading controls summer cyanobacterial blooms without promoting nitrogen‐fixing taxa: Long‐term response of a shallow lake. Limnology and Oceanography, 64(S1). <a href="https://doi.org/10.1002/lno.11002">https://doi.org/10.1002/lno.11002</a> Shatwell, Tom, and Jan Köhler. “Decreased Nitrogen Loading Controls Summer Cyanobacterial Blooms without Promoting Nitrogen‐fixing Taxa: Long‐term Response of a Shallow Lake.” Limnology and Oceanography 64, no. S1 (2018). <a href="https://doi.org/10.1002/lno.11002">https://doi.org/10.1002/lno.11002</a>. Shatwell T, Köhler J. Decreased nitrogen loading controls summer cyanobacterial blooms without promoting nitrogen‐fixing taxa: Long‐term response of a shallow lake. Limnology and Oceanography. 2018;64(S1). Shatwell, Tom/Köhler, Jan: Decreased nitrogen loading controls summer cyanobacterial blooms without promoting nitrogen‐fixing taxa: Long‐term response of a shallow lake, in: Limnology and Oceanography 64 (2018), H. S1. Shatwell T and Köhler J (2018) Decreased Nitrogen Loading Controls Summer Cyanobacterial Blooms without Promoting Nitrogen‐fixing Taxa: Long‐term Response of a Shallow Lake. Limnology and Oceanography 64. Shatwell, Tom, and Jan Köhler. “Decreased Nitrogen Loading Controls Summer Cyanobacterial Blooms without Promoting Nitrogen‐fixing Taxa: Long‐term Response of a Shallow Lake.” Limnology and Oceanography, vol. 64, no. S1, 2018, <a href="https://doi.org/10.1002/lno.11002">https://doi.org/10.1002/lno.11002</a>. T. Shatwell, J. Köhler, Decreased nitrogen loading controls summer cyanobacterial blooms without promoting nitrogen‐fixing taxa: Long‐term response of a shallow lake, Limnology and Oceanography. 64 (2018). 122372024-12-08T20:29:40Z2024-12-09T10:18:21Z