Baltic Sea oxygen levels at '1,500-year low due to human activity’

The coastal waters of the Baltic have been starved of oxygen to a level unseen in at least 1,500 years largely as a result of modern human activity, scientists say. Nutrient run-off from agriculture and urban sewage are thought to be to blame.

An algae slick off the German Baltic coast near the Fehmarn Sound Bridge in 2003.

“Dead zones” – areas of sea, typically near the bottom, with a dearth of oxygen – are caused by a rise in nutrients in the water that boosts the growth of algae. When these organisms die and sink to the seafloor, bacteria set to work decomposing them, using up oxygen in the process.

The resulting lack of oxygen not only curtails habitats for creatures that live on the seafloor, but also affects fish stocks and can lead to blooms of toxic cyanobacteria.

Read the story by Nicola Davis from The Guardian UK - “Baltic Sea oxygen levels at '1,500-year low due to human activity’.”