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A macro-tidal freshwater ecosystem recovering from hypereutrophication: the Schelde case study

Cox, T. J. S.; Maris, T.; Soetaert, K.; Conley, Daniel LU ; Van Damme, S.; Meire, P.; Middelburg, J. J.; Vos, M. and Struyf, Eric LU (2009) In Biogeosciences 6(12). p.2935-2948
Abstract
We report a 40 year record of eutrophication and hypoxia on an estuarine ecosystem and its recovery from hypereutrophication. After decades of high inorganic nutrient concentrations and recurring anoxia and hypoxia, we observe a paradoxical increase in chlorophyll-a concentrations with decreasing nutrient inputs. We hypothesise that algal growth was inhibited due to hypereutrophication, either by elevated ammonium concentrations, severe hypoxia or the production of harmful substances in such a reduced environment. We study the dynamics of a simple but realistic mathematical model, incorporating the assumption of algal growth inhibition. It shows a high algal biomass, net oxygen production equilibrium with low ammonia inputs, and a low... (More)
We report a 40 year record of eutrophication and hypoxia on an estuarine ecosystem and its recovery from hypereutrophication. After decades of high inorganic nutrient concentrations and recurring anoxia and hypoxia, we observe a paradoxical increase in chlorophyll-a concentrations with decreasing nutrient inputs. We hypothesise that algal growth was inhibited due to hypereutrophication, either by elevated ammonium concentrations, severe hypoxia or the production of harmful substances in such a reduced environment. We study the dynamics of a simple but realistic mathematical model, incorporating the assumption of algal growth inhibition. It shows a high algal biomass, net oxygen production equilibrium with low ammonia inputs, and a low algal biomass, net oxygen consumption equilibrium with high ammonia inputs. At intermediate ammonia inputs it displays two alternative stable states. Although not intentional, the numerical output of this model corresponds to observations, giving extra support for assumption of algal growth inhibition. Due to potential algal growth inhibition, the recovery of hypereutrophied systems towards a classical eutrophied state, will need reduction of waste loads below certain thresholds and will be accompanied by large fluctuations in oxygen concentrations. We conclude that also flow-through systems, heavily influenced by external forcings which partly mask internal system dynamics, can display multiple stable states. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Biogeosciences
volume
6
issue
12
pages
2935 - 2948
publisher
Copernicus Publications
external identifiers
  • wos:000273060100013
  • scopus:73449088490
ISSN
1726-4189
language
English
LU publication?
yes
id
f0a8ef06-9c0a-4216-ab27-83713bff728f (old id 1531765)
date added to LUP
2010-01-28 16:57:38
date last changed
2017-10-29 03:37:05
@article{f0a8ef06-9c0a-4216-ab27-83713bff728f,
  abstract     = {We report a 40 year record of eutrophication and hypoxia on an estuarine ecosystem and its recovery from hypereutrophication. After decades of high inorganic nutrient concentrations and recurring anoxia and hypoxia, we observe a paradoxical increase in chlorophyll-a concentrations with decreasing nutrient inputs. We hypothesise that algal growth was inhibited due to hypereutrophication, either by elevated ammonium concentrations, severe hypoxia or the production of harmful substances in such a reduced environment. We study the dynamics of a simple but realistic mathematical model, incorporating the assumption of algal growth inhibition. It shows a high algal biomass, net oxygen production equilibrium with low ammonia inputs, and a low algal biomass, net oxygen consumption equilibrium with high ammonia inputs. At intermediate ammonia inputs it displays two alternative stable states. Although not intentional, the numerical output of this model corresponds to observations, giving extra support for assumption of algal growth inhibition. Due to potential algal growth inhibition, the recovery of hypereutrophied systems towards a classical eutrophied state, will need reduction of waste loads below certain thresholds and will be accompanied by large fluctuations in oxygen concentrations. We conclude that also flow-through systems, heavily influenced by external forcings which partly mask internal system dynamics, can display multiple stable states.},
  author       = {Cox, T. J. S. and Maris, T. and Soetaert, K. and Conley, Daniel and Van Damme, S. and Meire, P. and Middelburg, J. J. and Vos, M. and Struyf, Eric},
  issn         = {1726-4189},
  language     = {eng},
  number       = {12},
  pages        = {2935--2948},
  publisher    = {Copernicus Publications},
  series       = {Biogeosciences},
  title        = {A macro-tidal freshwater ecosystem recovering from hypereutrophication: the Schelde case study},
  volume       = {6},
  year         = {2009},
}