Environment & ecosystems

Nutrient enrichment triggers a chain that ends in oxygen collapse. The killing step is not the algae growing but the algae dying.

There are around 200 chalk streams in the world and the great majority are in England. They are among the rarest freshwater habitats on Earth, and among the most pressured.

Tiny by volume, disproportionate in effect. Wetlands filter water, attenuate floods, and hold more carbon per hectare than almost any other habitat.