Ecosystem thresholds with hypoxia

Daniel Conley, Jacob Carstensen, Raquel Vaquer-Sunyer, Carlos M. Duarte

Research output: Chapter in Book/Report/Conference proceedingPaper in conference proceedingpeer-review

184 Citations (SciVal)


Hypoxia is one of the common effects of eutrophication in coastal marine ecosystems and is becoming an increasingly prevalent problem worldwide. The causes of hypoxia are associated with excess nutrient inputs from both point and non-point sources, although the response of coastal marine ecosystems is strongly modulated by physical processes such as stratification and mixing. Changes in climate, particularly temperature, may also affect the susceptibility of coastal marine ecosystems to hypoxia. Hypoxia is a particularly severe disturbance because it causes death of biota and catastrophic changes in the ecosystem. Bottom water oxygen deficiency not only influences the habitat of living resources but also the biogeochemical processes that control nutrient concentrations in the water column. Increased phosphorus fluxes from sediments into overlying waters occur with hypoxia. In addition, reductions in the ability of ecosystems to remove nitrogen through denitrification and anaerobic ammonium oxidation may be related to hypoxia and could lead to acceleration in the rate of eutrophication. Three large coastal marine ecosystems (Chesapeake Bay, Northern Gulf of Mexico, and Danish Straits) all demonstrate thresholds whereby repeated hypoxic events have led to an increase in susceptibility of further hypoxia and accelerated eutrophication. Once hypoxia occurs, reoccurrence is likely and may be difficult to reverse. Therefore, elucidating ecosystem thresholds of hypoxia and linking them to nutrient inputs are necessary for the management of coastal marine ecosystems. Finally, projected increases in warming show an increase in the susceptibility of coastal marine ecosystems to hypoxia such that hypoxia will expand.
Original languageEnglish
Title of host publicationHydrobiologia
Publication statusPublished - 2009
Event2nd International Symposium on Research and Management of Eutrophication in Coastal Ecosystems - Nyborg, Denmark
Duration: 2006 Jun 202006 Jun 23

Publication series

ISSN (Print)1573-5117
ISSN (Electronic)0018-8158


Conference2nd International Symposium on Research and Management of Eutrophication in Coastal Ecosystems

Subject classification (UKÄ)

  • Geology


  • Biogeochemistry
  • Nitrogen
  • Phosphorus
  • Resilience
  • Regime shift
  • Hypoxia


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