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  • Jane Hurd

Seaweed on the Beaches

Updated: Mar 26, 2023

A guest post by Jane Hurd, St. Mary’s, Isles of Scilly, @kernowweatherteam

Don't blame the weather, it's a much-needed part of life's great cycle, and is there for a purpose. Rough weather helps keep the sea's food chain going. Without the variations in the weather, the whole balance of the sea in coastal areas would be altered. That's why removing all the seaweed from the beaches, as is often done in tourist areas, is not a good idea.

The Benefits of Seaweed on the Beach

The stormy winds of recent days have brought benefits to all the creatures that live on or near the beaches, and some who live way beyond them. Removing the seaweed upsets the balance of the food web, from microscopic bacteria to the small black seaweed fly, which lays its eggs in the decaying algae.

If the seaweed is thrown up on a spring tide, or the weather and/or wind changes so that it's stranded where it last washed up then the eggs laid on it will grow into grubs which then grow on the rotting seaweed and provide a good food source for birds. If it's washed straight back into the sea then small sea-dwelling creatures will also feed on them.

Win-win for the creatures as big fish feed on little fish and life goes on.

While it's on the beach both land birds and sea birds feed on the grubs. There are so many eggs laid by the flies that there's plenty of food for all who need them and also for some to hatch for the next generation of flies.

Once the weed is washed back into the sea, there's a feeding frenzy as it feeds seabirds (and some that aren't sure, like the @Porthcressaseaducks!) as well as fish, molluscs and then a myriad of small sea dwelling creatures as it sinks to the bottom and decomposes.

There's also enough to be taken by gardeners, as seaweed is one of the best fertilizers of all for the garden and farms. Generations of coastal farmers have used it on their fields, and still do in places such as Scilly. Seaweed is added directly to the soil to improve the soil structure and moisture retention while it gives nutrients to plants as it decomposes. The addition of seaweed also encourages helpful microscopic organisms in the soil while decreasing pests.


Through the seaweed, the balance of the whole food chain in and around the coast and sea continues, and it all depends on the weather.


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