Blog 9 - Dunes love seaweed

Seaweed can wash up in large quantities on some beaches

The skinny

For dune plants, seaweed is a source of nutrients, water, shelter from wind and trampling. It traps sand, building new dunes, and supports biodiversity. Dunes are a natural coastal protection.

Tough plants

The upper beach and seaward facing dunes are tough places for plants to survive. And plants are the key to stabilising dunes, holding the sand in place. Healthy beaches and dune are a natural buffer against coastal erosion and flooding, a nature-based solution to climate change impacts.

Benefits of washed up seaweed

Management options for washed-up seaweed:

Where seaweed washes up in large quantities on beaches that are heavily used, usually after winter and spring storms, there is often pressure on management to remove it due to bad smell, aesthetics and the space it takes up.

Management Option 1 - Removing seaweed completely will

Mechanical clearing of seaweed

1. Be costly

2. Result in the benefits described above being lost

3. Prevent the beach and dunes (if present) recovering naturally – contributing to erosion at the site

4. Remove sand too – also contributing to erosion at the site

5. Severely damage habitat quality and biodiversity

This approach is a humans-first, short-term action, going against our global battle against climate change impacts and biodiversity loss.

Management Option 2 - Leaving the seaweed completely untouched may

1. Result in the benefits described above, enhancing the coastal protection and habitat quality

2. Reduce use of the beach due to reduced user access and mobility, aesthetics and smell

3. Be perceived as a lack of management (and may be a lack of management!), and is the cheap option

• the “seaweed nuisance” (when it is rotting and decaying) generally lasts only a number of weeks long, and this is normally not during the busy summer period

Example of a project using washed-up seaweed on to restore coastal dunes

Available at: https://www.ayrshiredailynews.co.uk/news/troon-dunes-restoration-project-lands-prestigious-uk-award

Example from McKenna (2000) Rural Beach Management A Good Practice Guide

Available at: https://www.semanticscholar.org/paper/Rural-Beach-Management%3A-A-Good-Practice-Guide-Mckenna-MacLeod/b7da8415836e4a0e524ce37e34Notes

Dunes are by their nature low nutrient places where the unique plants and animals that are valued the world over live, we do not want to over-use the seaweed spreading technique as it will promote non-dune grasses and species which would take over and lower biodiversity and habitat value.

Not alone does seaweed provide nutrients and trap sand, it often traps seeds and can carry in small root fragments that regenerate dune plants.