LONG‐TERM CHANGES AND IMPACTS OF HYPOXIA IN DANISH COASTAL WATERS

作者：Daniel J. Conley, Jacob Carstensen, Gunni Ærtebjerg, Peter Bondo Christensen, Tage Dalsgaard, Jørgen L. S. Hansen, Alf B. Josefson · 发表于：Ecological Applications · 年份：2007 · DOI：10.1890/05-0766.1 · 被引用次数：326 · 研究领域：Marine and coastal ecosystems、Marine Biology and Ecology Research、Marine Bivalve and Aquaculture Studies

A 38‐year record of bottom‐water dissolved oxygen concentrations in coastal marine ecosystems around Denmark (1965–2003) and a longer, partially reconstructed record of total nitrogen (TN) inputs (1900–2003) were assembled with the purpose of describing long‐term patterns in hypoxia and anoxia. In addition, interannual variations in bottom‐water oxygen concentrations were analyzed in relation to various explanatory variables (bottom temperature, wind speed, advective transport, TN loading). Reconstructed TN loads peaked in the 1980s, with a gradual decline to the present, commensurate with a legislated nutrient reduction strategy. Mean bottom‐water oxygen concentrations during summer have significantly declined in coastal marine ecosystems, decreasing substantially during the 1980s and were extremely variable thereafter. Despite decreasing TN loads, the worst hypoxic event ever recorded in open waters occurred in 2002. For estuaries and coastal areas, bottom‐water oxygen concentrations were best described by TN input from land and wind speed in July–September, explaining 52% of the interannual variation in concentrations. For open sea areas, bottom‐water oxygen concentrations were also modulated by TN input from land; however, additional significant variables included advective transport of water and Skagerrak surface‐water temperature and explained 49% of interannual variations in concentrations. Reductions in the number of benthic species and alpha diversity were significan...