Unlocking the secrets of our seaweeds to track change on British seashores.

The Big Seaweed Search first launched in 2009. Hundreds of people have taken part and the data gathered, alongside other research, show that the distribution of seaweeds around the UK is changing. 

We need more people to record the seaweeds on Britain and Northern Ireland’s coastlines to support research on three key environmental issues:

  • rising sea temperature
  • the arrival and spread of non-native species of seaweeds
  • ocean acidification (the sea becoming more acidic because of absorbing carbon dioxide from the air

Why seaweeds?

Seaweeds form the forests of the sea – providing shelter and food for thousands of marine animals. Seaweeds are also important for people, they provide a habitat for fish we catch, are used in food, cosmetics, and medicines, and protect our coasts by reducing wave and storm damage. This economic as well as environmental value means it is important for us to monitor seaweeds so we can understand and sustainably manage them. 

The British Isles is globally important for seaweed diversity, being home to more than 650 species. Unfortunately, seaweeds are not as popular as flowers, butterflies, or birds, so fewer people make and submit observations of them. Whether you live near the coast or are just visiting consider taking part in the Big Seaweed Search. 

Join the Big Seaweed Search

Meet seaweed researcher Juliet Brodie and Big Seaweed Search participant Jazz in this short video and learn more about why seaweeds are important and how you can take part (3:46 mins).

What do you need to do?

You can take part in the Big Seaweed Search at any seashore in the UK at any time of the year. For details of the survey, and to download or order a survey guide visit how to take part. Organising a Big Seaweed Survey as a group activity? Download our Guide for Group Leaders PDF (4.93MB)

The Big Seaweed Search guide includes instructions on how to take part and an identification guide for the 14 seaweeds we are asking you to record. There is also a recording form where you can write down your observations and other important information about your survey site. You can download and print your own guide and recording form from these links:

Big Seaweed Search guide PDF (3.3MB)

Recording form PDF (71KB)

If you require a printed version of the identification guide and recording form please email seaweeds@nhm.ac.uk with your name, address and how many you require. We have limited capacity to post hard copies of the Big Seaweed Search survey pack, so there may be a wait.