Big Seaweed Search

The Big Seaweed Search is a joint project between the Marine Conservation Society and the Natural History Museum. The Big Seaweed Search asks volunteers to identify, photograph and record 14 key seaweed species that can be found around the UK coastline.

Report your seaweed search findings

It may be a bit slippery and slimy, but seaweed is a real ocean superhero. Studying seaweeds can tell us a lot about wider ocean and environmental conditions. By taking part in the Big Seaweed Search, you’ll be helping to gather vital evidence that can be used to map and document any changes to our coastal environments.

Whether you live by the sea or only visit every now and again, you can get involved in the Big Seaweed Search! It’s free, fun, and suitable for everyone – you don’t need to be a scientist to get involved.

The more data we gather, the more knowledge and influence we have to fight for the future of our seas.

How to become a seaweed citizen scientist

First, you'll need a seaweed guide and a recording form. You can download and print these below.

If you'd like a printed version of the identification guide or recording form, you can email the team at seaweeds@nhm.ac.uk including your name, address and the number of guides you would like.

If you need any further assistance to access our resources, please contact us.

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English
Big Seaweed Search guide

Big Seaweed Search recording form

Welsh

Llyfryn Chwiliad Gwymon Mawr

Ffurflen gofnodi

We want you to have fun at the beach, but it's always important to make sure you're staying safe. Check out the safety information in your Big Seaweed guide booklet before you start searching.

Try to start your survey an hour before low tide. This time is best for your safety and for seaweed spotting, too. You can check tide times for your chosen beach at www.tidetimes.co.uk

All shores are important for seaweed research, but you'll find more seaweeds on shores with hard structures like rocks, sea walls and piers, as many species anchor themselves to these.

Select a five metre wide plot that runs from the top of the shore down to the sea - five metres is around five adult paces. You can mark your survey area with a bucket, sticks, or using natural landmarks.

Stand with your back to the sea and take a picture of your survey area. This gives our scientists a good idea of the conditions on the shore where you've carried out your survey.

Walking away from the sea, explore the whole of your five metre wide plot - you might need to get your hands wet! Aim to cover your whole survey area in under an hour.

When you find one of the target seaweeds:

Tick it off as ‘present’ on your recording form
Take a clear picture of its identifying features - you need to do this for every species you find
Record it as band forming, patchy, or sparse - if you later find a larger patch afterwards, update your recording form.

Download our handy guide to taking photos

Remember, only record living species which are attached to the rocks. Ignore any seaweed which is washed up on the beach, as it could have been transported from anywhere around the coast in storms and big waves.

Now, the really important bit! Tell us what you have found. You can even do this on the beach using your phone.

There's a button to upload your pictures so our scientists can confirm what you've spotted. You can upload three images for each seaweed species you found.

The button below will direct you to an external site. For more information on how your data is used, please read the privacy policy on the Big Seaweed Search website.

Report your Big Seaweed Search findings!

Are you looking to run a group survey?

We've put together a handy guide for group leaders with some top tips on taking a group of seaweed searchers to the beach.

Download the group guide

Unsure about the difference between seaweeds?

We have you covered. Check out the 14 seaweed types we want to record, what they look like and why we are interested to know about them.

Identify each seaweed

Take our seaweed quiz

Our coast is home to an amazing variety of seaweeds. 650 different species live and grow around the UK. Do you know your dabberlocks from your bladder wrack? Test your knowledge with our seaweed quiz to find out if you're a novice or ninja. You might learn some surprising facts about seaweed along the way.

Using the Big Seaweed Search data

Hundreds of volunteers have submitted data which shows how the distribution of seaweeds around the UK is changing. This information helps us to take action to protect our coastlines, seaweeds, and all the amazing wildlife that depend on them.

The Big Seaweed Search tracks and records these changes around the coast each year, so we can understand the impact of environmental change on our seas. This information supports real scientific research, which we can use to protect our ocean, and seaweeds, for the future.

3 people huddled around a stream of water on a beach looking in depth at some live seaweed. They are surrounded by seaweed. All three are holding clipboards.

Volunteers participating in a Big Seaweed Search survey | Image credit: Billy Barraclough

Big Seaweed Search reports

Big Seaweed Search Report 24/25

Every year we share your seaweed findings, including our favourite pictures, interesting finds, and what we've done with the data. Check out the 2024-2025 report.

A wide shot of seaweed on the sandy shores of the Scottish Atlantic Coast. In the distance are rolling hills.

Seaweed science study 2022

Discover the results discovered by a study undertaken by the Big Seaweed Search team about the impact of the Big Seaweed Search

Meet the team

Professor Juliet Brodie

Professor Juliet Brodie is a leading seaweed researcher working at the Natural History Museum in London. Juliet leads the Big Seaweed Search and uses the information collected from your surveys in her scientific research.

"By mapping where different seaweed species are we can create a baseline from which we can monitor and determine the impact of environmental changes on our seas"

Professor Juliet Brodie standing in a rocky tidal pool with seaweed.

Professor Juliet Brodie conducting seaweed research

Learn more about seaweed

The potential of seaweed

Seaweed is something we’re all familiar with from trips to the beach, but its potential as a business opportunity for the aquaculture industry is now emerging.

An orange lumpsucker fish hiding in some kelp.

What seaweed can teach us about climate change

There are over 650 species of seaweed found around the UK and each plays a vital role in supporting the health of our ocean and planet and can tell us key information about the effects of climate change.

Meet the seaweed types

There are over 650 species of seaweed found around the UK and we’re on the lookout for 14 of them for The Natural History Museum and Marine Conservation Society's Big Seaweed Search.

This project is funded by the Government's Green Recovery Challenge Fund. The fund was developed by Defra and its Arm's-Length Bodies. It is being delivered by The National Lottery Heritage Fund in partnership with Natural England, the Environment Agency and Forestry Commission.