Department of Bioscience, Aarhus University, DK-4000 Roskilde, Denmark.
Proc Natl Acad Sci U S A. 2014 Apr 15;111(15):5628-33. doi: 10.1073/pnas.1323156111. Epub 2014 Mar 31.
Deoxygenation is a global problem in coastal and open regions of the ocean, and has led to expanding areas of oxygen minimum zones and coastal hypoxia. The recent expansion of hypoxia in coastal ecosystems has been primarily attributed to global warming and enhanced nutrient input from land and atmosphere. The largest anthropogenically induced hypoxic area in the world is the Baltic Sea, where the relative importance of physical forcing versus eutrophication is still debated. We have analyzed water column oxygen and salinity profiles to reconstruct oxygen and stratification conditions over the last 115 y and compare the influence of both climate and anthropogenic forcing on hypoxia. We report a 10-fold increase of hypoxia in the Baltic Sea and show that this is primarily linked to increased inputs of nutrients from land, although increased respiration from higher temperatures during the last two decades has contributed to worsening oxygen conditions. Although shifts in climate and physical circulation are important factors modulating the extent of hypoxia, further nutrient reductions in the Baltic Sea will be necessary to reduce the ecosystems impacts of deoxygenation.
脱氧作用是海洋沿海和开阔区域的一个全球性问题，导致了氧气最小区和沿海缺氧区的扩大。最近沿海生态系统缺氧的扩大主要归因于全球变暖以及陆地和大气中营养物质输入的增加。世界上人为诱导的最大缺氧区是波罗的海，其物理强迫与富营养化的相对重要性仍存在争议。我们分析了水柱中的氧气和盐度剖面，以重建过去 115 年来的氧气和分层条件，并比较了气候和人为强迫对缺氧的影响。我们报告了波罗的海缺氧程度增加了 10 倍，并表明这主要与陆地输入的营养物质增加有关，尽管过去二十年由于温度升高导致的呼吸作用增加也导致了氧气条件恶化。尽管气候和物理循环的转变是调节缺氧程度的重要因素，但波罗的海仍需要进一步减少营养物质的输入，以减轻脱氧作用对生态系统的影响。
