© Richard Harrington

Big Seaweed Search

Contribute to research by recording seaweed species found on your local shore

© Natasha Ewins

The Big Seaweed Search is a partnership between the Natural History Museum and the Marine Conservation Society.

UK coasts and shallow seas are nicknamed a “goldilocks” zone for seaweeds - it is not too hot, not too cold for them. In fact, conditions are just right! Over 650 species live and thrive around our shores.

But marine environments are changing – sea temperatures are increasing, sea levels are rising and the ocean is becoming more acidic, and this is affecting the distribution of different species of seaweed.

We want to know more about some of the seaweed species found in UK waters, identifying exactly where they are found and how this may change over time.

Here’s where you come in - we want you to head to the coast this summer and start exploring!

It’s easy to take part. A Big Seaweed Search guide explains what you need to do, and helps you to identify each of the seaweeds we are focussing on. You can complete the simple survey on a mobile, tablet or pc.

What we’re looking for

…People to take part in the Big Seaweed Survey! All you need to do is use the ID guides and submit data on the 14 seaweed species listed. The species have been chosen as they may indicate changes in our seas, for example:


Coral weed Corallina sp, a red-pink species with a chalky structure that could be affected by changing acidity levels in seawater.

Introduced species

Wakame (Undaria pinnatifida) is a kelp like weed that isn’t native to our shores and is spreading its range.

Temperature rise

Wracks such as bladder wrack (Fucus vesiculosus) and other seaweeds may be affected by rising sea temperatures.

Actions you can take

  1. Register to take part in the Big Seaweed Search

Did you know?…

Every year, volunteers give us over 1,000 days of their time

MCS encourages people to visit the coast, learn about the marine environment and enjoy it and provides ways they can help to keep it healthy and productive into the future

Last year, over 300 Seasearch divers spent over 8 weeks surveying underwater