Feb 1, 2011

Coupled biogeochemical cycles: eutrophication and hypoxia in temperate estuaries and coastal marine ecosystems

Howarth, Robert, Chan, Francis, Conley, Daniel J, Garnier, Josette, Doney, Scott C, Marino, Roxanne, Billen, Gilles
Frontiers in Ecology and the Environment
  • States that primary production in most temperate estuaries and coastal marine ecosystems is nitrogen (N) limited, although phosphorus (P) also contributes to eutrophication
  • Finds that during eutrophication, biogeochemical feedbacks act to further increase the availability of N and P, but to decrease the availability of silica; this positive feedback accelerates eutrophication and hypoxia, and makes harmful algal blooms more likely
  • Changes in ocean circulation patterns over recent decades have increased the sensitivity of some estuaries and coastal systems to becoming hypoxic from nutrient pollution
  • Finds that decreased levels of dissolved oxygen – low in hypoxic waters and absent in anoxic waters – are associated with elevated carbon dioxide (CO2) concentrations, which cause acidification and increase the vulnerability of estuaries and coastal systems to continuing perturbations of ocean chemistry from anthropogenic CO2 emissions into the atmosphere