Algae chokes estuaries on south coast as England enjoys hottest day of year

Steve Connor in the Independent (UK): A combination of calm, sunny weather and high concentrations of nitrate pollutants running into the sea from local farms and sewage works has caused thick mats of green algae to form at a dozen sites on the south coast.

The Environment Agency said yesterday that it was concerned that the seaweed could cause long-term damage to the unique wildlife of some of the most important coastal mudflats which are being slowly starved of oxygen by the algae as it spreads over wide areas of the southern shoreline.

…Sunny weather has helped the algae to grow. Near the Isle of Wight, the seaweed has formed layers up to a foot deep and the mud underneath has turned black because of lack of oxygen, said Dave Lothian, a marine scientist at the Environment Agency who is tracking the extent of the problem. "It's hard to gauge how bad it is this year but we know of several sites in and around the Solent that are affected. The point is, this is an unnatural state because there shouldn't be so much seaweed," Mr Lothian said.

….Algae grows rapidly in the presence of nitrates from agricultural fertilisers and the effluent from sewage-treatment plants. There are two forms of marine algae that are affected by nutrient run-off from the land. One is the microscopic plants or phytoplankton that can result in toxic "red tides", and the other is the larger algal seaweeds that grow near estuaries and have no roots to anchor themselves to the seabed….

An old pony by the Solent, shot by Jim Champion, Wikimedia Commons, under the Creative Commons Attribution ShareAlike 3.0 License