Beach Hut owners making their way down to the beach in the last two weeks have been concerned at the aroma and look of the water. The water has taken on a colour of rusty brown with layers of scum on the surface. Fears around what the source of the brown colour and smell can be allayed, its not caused by the sewage system unable to cope with the heavy downpours that can be experienced in a British summer and it is not caused by polution from a stricken ship leaking oil into our water, The cause of the brown colour and smell is a harmless algae called Phaoecystis.
Phaeocystis is a genus of algae belonging to the Prymnesiophyte class and to the larger division of Haptophyta. It is a widespread marine phytoplankton and can function at a wide range of temperatures (eurythermal) and salinities (euryhaline). Members of this genus live in the open ocean, as well as in sea ice. It has a polymorphic life cycle, ranging from free-living cells to large colonies.
Dr Richard Kirby an Independent plankton scientist advised the Bournemouth Echo that
It grows as colonies of thousands of cells within a jelly-like matrix. When a bloom dies the dead colonies can be whipped-up by wind and waves into a surface foam that is called spume. Bournemouth last had a phaeocystis phytoplankton bloom in 2016 after the beach sand replenishment, and that was the first one I had seen in Bournemouth since 2010. This one is very strong but not as strong as the one in 2016.”
“This particular phaeocystis plankton plant often blooms when you get a period of strong sunlight and warm weather, together with nutrients building up in the sea. “They happen this time every year somewhere around the coast. It’s a completely natural event, although it doesn’t look very nice. “It will clear up within the next week or ten days at most once it has died off, at which point it will sink to the sea bed.”
The Environment Agency have previously stated "Once onshore it breaks down into a brown slime which can smell similar to sewage."