@misc{12237,
  abstract     = {{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.}},
  author       = {{Shatwell, Tom and Köhler, Jan}},
  booktitle    = {{Limnology and Oceanography}},
  issn         = {{1939-5590}},
  number       = {{S1}},
  publisher    = {{Wiley}},
  title        = {{{Decreased nitrogen loading controls summer cyanobacterial blooms without promoting nitrogen‐fixing taxa: Long‐term response of a shallow lake}}},
  doi          = {{10.1002/lno.11002}},
  volume       = {{64}},
  year         = {{2018}},
}

@misc{12238,
  abstract     = {{Phytoplankton growth depends not only on mean intensity but also on the dynamics of the light supply. In surface mixed layers, phytoplankton may rapidly move between strong light and almost darkness. The nonlinear light‐dependency of growth may differ between constant and fluctuating light because of the different frequency distribution of light and/or acclimation processes. The present study compares for the first time light‐dependency of photosynthesis and growth of phytoplankton communities in situ under defined mixing conditions and at fixed depths. Maximum growth rates per day were not significantly different, but the growth efficiency was much higher under constant light than under fluctuating light of sub‐saturating daily irradiance. Phytoplankton incubated under fluctuating light needed about three times higher mean daily irradiances to balance photosynthesis and losses than under constant light. The difference in growth efficiency was mostly caused by the different frequency distribution of underwater light, as was estimated by a photosynthesis model of sufficient temporal resolution. The present study indicates a considerable overestimation of phytoplankton growth at sub‐saturating light in well‐mixed water layers by the common growth measurements under constant light. This implies an underestimation of the compensation light intensities and respective overestimations of the critical mixing depths.}},
  author       = {{Köhler, Jan and Wang, Lan and Guislain, Alexis and Shatwell, Tom}},
  booktitle    = {{Limnology and Oceanography}},
  issn         = {{1939-5590}},
  number       = {{3}},
  pages        = {{1156--1167}},
  publisher    = {{Wiley}},
  title        = {{{Influence of vertical mixing on light‐dependency of phytoplankton growth}}},
  doi          = {{10.1002/lno.10761}},
  volume       = {{63}},
  year         = {{2017}},
}

@misc{12250,
  abstract     = {{We measured specific growth rates of Stephanodiscus minutulus, Nitzschia acicularis (diatoms), and Limnothrix redekei (cyanobacterium) under fluctuating and constant light in semi-continuous culture at 10°C, 15°C, and 20°C and under photoperiods of 6 h d−1 and 12 h d−1. Fluctuating light regimes simulated regular vertical mixing in lakes with a ratio of euphotic to mixed depth (zeu : zmix) of 1 and 0.5 on a cloudless day. Light fluctuations at zeu : zmix = 1 decreased the growth rates of S. minutulus, N. acicularis, and L. redekei by 18%, 33%, and 29%, respectively, compared to constant light at the same daily light supply. Temperature had no effect on this decrease. Halving zeu : zmix (simulating deep mixing) had the same effect on growth as halving the photoperiod, demonstrating that these factors are cumulative. We introduce a simple empirical factor to adjust growth rates measured under constant light to account for fluctuating light. This factor is independent of temperature and photoperiod, applies over a range of zeu : zmix, and accurately describes present and published growth rates of several species. We show how to account for temporal variability of the light supply at different temperatures and photoperiods when predicting growth rates of phytoplankton.}},
  author       = {{Shatwell, Tom and Nicklisch, Andreas and Köhler, Jan}},
  booktitle    = {{Limnology and Oceanography}},
  issn         = {{0024-3590}},
  number       = {{2}},
  pages        = {{541--553}},
  publisher    = {{Wiley}},
  title        = {{{Temperature and photoperiod effects on phytoplankton growing under simulated mixed layer light fluctuations}}},
  doi          = {{10.4319/lo.2012.57.2.0541}},
  volume       = {{57}},
  year         = {{2012}},
}