Exploring the shoreline and its seaweed
The Big Seaweed Survey and how you can help track ocean health
Late last year our ranger team headed to the coast for a hands-on day learning about seaweed with the Marine Conservation Society (MCS). Seaweed may not grab the spotlight in the same way as dolphins or seabirds, but it’s a mighty contributor to the health of our seas – and one of our most insightful natural indicators of the pace of climate change.
Why Seaweed?
Seaweed is essential to the marine ecosystem. These incredible plants produce oxygen, store carbon, and provide food and shelter for countless species. But they’re also sensitive to shifts in temperature, water chemistry, and other environmental changes, which makes them excellent indicators of climate change. By studying where and when certain types of seaweed are found, scientists can trace patterns that reveal how our oceans are warming or becoming more acidic.
Can you eat seaweed?
We often get asked this question and the answer is that seaweed is relatively safe to eat here in the UK, and coastal communities have enjoyed it for centuries. You might have already tried Welsh laverbread, made from the delicious laver seaweed. Another UK favourite is kelp. While there aren’t really any poisonous seaweeds native to the UK, some species might upset your stomach if eaten raw or in large amounts, as seaweed can soak up pollutants from dirty water and metals in the sea. Many coastal areas in the Highlands are marine protected environments so it's generally best to avoid foraging it.
Join the Big Seaweed Search instead!
The Big Seaweed Search is an accessible citizen science project open to anyone with a curiosity about marine life. Participants are encouraged to head to their nearest beach, record what species they find, and submit their observations to the MCS and Natural History Museum, the two main partners running this initiative.
Through the Big Seaweed Search citizen science project, anyone can sign up to help track how our seas are changing and contribute valuable data that can help scientists understand the effects of ocean warming and acidification.
Here’s a handy step-by-step guide to help you get involved:
Prepare for the Search – Download the Big Seaweed Search guide, which helps you identify 14 common seaweed species on UK shores.
Head to the Coast – Make sure you’re equipped with a camera or smartphone to capture photos of your finds and pick a stretch of shoreline. You don’t need to go far – even small areas of coastline can be home to diverse seaweed species.
Observe and Record – Look for the 14 seaweed types listed in the guide, focusing on the shapes, colours, and sizes to help with identification. Some key species include the bushy Channelled Wrack and the striking Bladder Wrack with its air-filled sacs. You’ll be recording how much of the seaweed you can see, as well as the type.
Submit Your Findings – Once you’ve made your observations, submit your results online through the Big Seaweed Search website. You’ll be helping build a valuable dataset that MCS and the Natural History Museum will use to monitor trends in seaweed populations and health.
Four Fantastic Finds: Seaweed to Spot
To get you started, here’s a quick guide to four main types of seaweed you’ll likely encounter along the UK shoreline:
Bladder Wrack (Fucus vesiculosus): Spot the bubbles! Bladder wrack is hard to miss, with its iconic air-filled bladders along both sides of the stem. These little pockets help the seaweed float, so it can reach the sunlight needed for photosynthesis. It’s great for snapping photos and a popular one to find.
Spiral Wrack (Fucus spiralis): Known for its tightly curled fronds that look, well, spirally! This seaweed grows high up on the shore and can survive out of the water for longer periods. It has these goo filled bladders instead of air, and they are quite distinctive looking!
Channel Wrack (Pelvetia canaliculata): Look closely, and you’ll see little grooves running down the length of each frond – these channels give Channel Wrack its name. Found even higher up the shore, it’s usually one of the first seaweeds you’ll encounter, clinging to rocks above the tide line.
Toothed Wrack (Fucus serratus): This one’s a beauty! With serrated, saw-like edges along its fronds, giving it a “toothy” appearance. Toothed Wrack often grows lower down on the shore, closer to the water, where it thrives in the salty spray.
Now to Find Out More
Getting started with the Big Seaweed Search is really easy, and there’s plenty of support available:
Marine Conservation Society – Their website has a full toolkit, identification guides, and insights into how your contributions aid scientific understanding of marine changes.
Natural History Museum – The Big Seaweed Search partner, the Museum, offers resources on marine biodiversity and the effects of climate change on coastal ecosystems.
Whether you're a seasoned coastal explorer or just getting curious about marine life, joining the Big Seaweed Search is a brilliant way to spend time in nature, deepen your understanding of our oceans, and make a meaningful contribution to science whilst enjoying a fresh air walk along the coastline.
So, grab a guide, head to the shore, and start identifying – your observations will help the project to shape and protect the future of our coastal ecosystems.
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