@article{BrothersKoehlerAttermeyeretal.2014,
  author    = {Brothers, Soren M. and Koehler, J. and Attermeyer, Katrin and Grossart, Hans-Peter and Mehner, T. and Meyer, N. and Scharnweber, Inga Kristin and Hilt, Sabine},
  title     = {A feedback loop links brownification and anoxia in a temperate, shallow lake},
  series = {Limnology and oceanography},
  volume    = {59},
  journal   = {Limnology and oceanography},
  number    = {4},
  publisher = {Wiley-Blackwell},
  address   = {Hoboken},
  issn      = {0024-3590},
  doi       = {10.4319/lo.2014.59.4.1388},
  pages     = {1388 -- 1398},
  year      = {2014},
  abstract  = {This study examines a natural, rapid, fivefold increase in dissolved organic carbon (DOC) concentrations in a temperate shallow lake, describing the processes by which increased DOC resulted in anoxic conditions and altered existing carbon cycling pathways. High precipitation for two consecutive years led to rising water levels and the flooding of adjacent degraded peatlands. Leaching from the flooded soils provided an initial increase in DOC concentrations (from a 2010 mean of 12 +/- 1 mg L-1 to a maximum concentration of 53 mg L-1 by June 2012). Increasing water levels, DOC, and phytoplankton concentrations reduced light reaching the sediment surface, eliminating most benthic primary production and promoting anoxia in the hypolimnion. From January to June 2012 there was a sudden increase in total phosphorus (from 57 mg L-1 to 216 mg L-1), DOC (from 24.6 mg L-1 to 53 mg L-1), and iron (from 0.12 mg L-1 to 1.07 mg L-1) concentrations, without any further large fluxes in water levels. We suggest that anoxic conditions at the sediment surface and flooded soils produced a dramatic release of these chemicals that exacerbated brownification and eutrophication, creating anoxic conditions that persisted roughly 6 months below a water depth of 1 m and extended periodically to the water surface. This brownification-anoxia feedback loop resulted in a near-complete loss of macroinvertebrate and fish populations, and increased surface carbon dioxide (CO2) emissions by an order of magnitude relative to previous years.},
  language  = {en}
}
@article{LischkeHiltJanseetal.2014,
  author    = {Lischke, Betty and Hilt, Sabine and Janse, Jan H. and Kuiper, Jan J. and Mehner, Thomas and Mooij, Wolf M. and Gaedke, Ursula},
  title     = {Enhanced input of terrestrial particulate organic matter reduces the resilience of the clear-water state of shallow lakes: A model study},
  series = {Ecosystems},
  volume    = {17},
  journal   = {Ecosystems},
  number    = {4},
  publisher = {Springer},
  address   = {New York},
  issn      = {1432-9840},
  doi       = {10.1007/s10021-014-9747-7},
  pages     = {616 -- 626},
  year      = {2014},
  abstract  = {The amount of terrestrial particulate organic matter (t-POM) entering lakes is predicted to increase as a result of climate change. This may especially alter the structure and functioning of ecosystems in small, shallow lakes which can rapidly shift from a clear-water, macrophyte-dominated into a turbid, phytoplankton-dominated state. We used the integrative ecosystem model PCLake to predict how rising t-POM inputs affect the resilience of the clear-water state. PCLake links a pelagic and benthic food chain with abiotic components by a number of direct and indirect effects. We focused on three pathways (zoobenthos, zooplankton, light availability) by which elevated t-POM inputs (with and without additional nutrients) may modify the critical nutrient loading thresholds at which a clear-water lake becomes turbid and vice versa. Our model results show that (1) increased zoobenthos biomass due to the enhanced food availability results in more benthivorous fish which reduce light availability due to bioturbation, (2) zooplankton biomass does not change, but suspended t-POM reduces the consumption of autochthonous particulate organic matter which increases the turbidity, and (3) the suspended t-POM reduces the light availability for submerged macrophytes. Therefore, light availability is the key process that is indirectly or directly changed by t-POM input. This strikingly resembles the deteriorating effect of terrestrial dissolved organic matter on the light climate of lakes. In all scenarios, the resilience of the clear-water state is reduced thus making the turbid state more likely at a given nutrient loading. Therefore, our study suggests that rising t-POM input can add to the effects of climate warming making reductions in nutrient loadings even more urgent.},
  language  = {en}
}
@article{SachsePetzoldtBlumstocketal.2014,
  author    = {Sachse, Rene and Petzoldt, Thomas and Blumstock, Maria and Moreira, Santiago and Paetzig, Marlene and Ruecker, Jacqueline and Janse, Jan H. and Mooij, Wolf M. and Hilt, Sabine},
  title     = {Extending one-dimensional models for deep lakes to simulate the impact of submerged macrophytes on water quality},
  series = {Environmental modelling \& software with environment data news},
  volume    = {61},
  journal   = {Environmental modelling \& software with environment data news},
  publisher = {Elsevier},
  address   = {Oxford},
  issn      = {1364-8152},
  doi       = {10.1016/j.envsoft.2014.05.023},
  pages     = {410 -- 423},
  year      = {2014},
  abstract  = {Submerged macrophytes can stabilise clear water conditions in shallow lakes. However, many existing models for deep lakes neglect their impact. Here, we tested the hypothesis that submerged macrophytes can affect the water clarity in deep lakes. A one-dimensional, vertically resolved macrophyte model was developed based on PCLake and coupled to SALMO-1D and GOTM hydrophysics and validated against field data. Validation showed good coherence in dynamic growth patterns and colonisation depths. In our simulations the presence of submerged macrophytes resulted in up to 50\% less phytoplankton biomass in the shallowest simulated lake (11 m) and still 15\% less phytoplankton was predicted in 100 m deep oligotrophic lakes. Nutrient loading, lake depth, and lake shape had a strong influence on macrophyte effects. Nutrient competition was found to be the strongest biological interaction. Despite a number of limitations, the derived dynamic lake model suggests significant effects of submerged macrophytes on deep lake water quality. (C) 2014 Elsevier Ltd. All rights reserved.},
  language  = {en}
}