COAST celebrates seagrass

The following information has been published on the COAST Facebook page and collected here for the Voice. The featured image shows Seagrass in the waves on sand, photo credit Lucy Kay.

As Scotland celebrates the Year of Coasts and Waters, COAST celebrates 25 years of the community of Arran’s efforts to protect our seas. Each month over this year, we are aiming to bring you a little bit closer to what lies beneath our waves with a monthly focus in social media, the press and on our website of a particular species or habitat found within the South Arran Marine Protected Area. This month’s feature focuses magical world of Seagrass, meadows of which are found in Scotland’s seas, so keep an eye on our social media platforms this month to discover more about these mesmerising habitats.

On land we take grass for granted. Underwater, seagrass can only thrive in very specific conditions and so is quite unusual to see. It is a very special plant which is only found at certain locations in the waters around Arran, where it generally grows in sandy seabeds. Although seagrass may not sound very exciting, it is responsible for creating a vitally important underwater habitat.

Seagrass is actually a true flowering plant, the only flowering plant able to live in seawater and pollinate and produce seeds while submerged. The two seagrass species we have in the UK – eelgrass and dwarf eelgrass – are both found in the Clyde, but it is the larger of the two, eelgrass (Zostera marina) that is found around Arran.

Like other plants, seagrasses need sunlight to survive and can only live in well-lit, shallow water just a few metres deep. They are usually found in quite sheltered conditions and can grow closely together forming dense underwater meadows or seagrass beds. One of the largest remaining seagrass beds in the Clyde is just off shore at Whiting Bay and, together with other areas of seagrass, is part of the special interest underpinning the establishment of the South Arran Marine Protected Area (MPA).

There’s SO many amazing things about seagrass, where do we even start?! The thin, tall seagrass leaves can grow up to a metre long – depending on local conditions – and acts as shelter, feeding and nursery areas for many different species. Studies show that seagrass beds provide good nursery grounds for a number of commercially important fish including juvenile cod, whiting and pollock.
Within the seabed itself, a specialised root system anchors the plants, helping to stabilise and consolidate the seabed material. This has been shown to help to reduce sediment erosion and thus provide a form of natural coastal defence.

Seagrass diagram – Project Seagrass

And seagrass beds are VERY effective at capturing and storing carbon, locking it away in the seabed sediments. Globally it is suggested that they are responsible for about 15% of the total carbon storage in the ocean. They also capture this at a rate greater (35 times more efficiently) than that of tropical rainforests!

We’d highly recommend exploring Arran’s seagrass beds yourselves, as the accessibility of some to swimmers, snorkellers and divers provides an opportunity to enjoy this special marine habitat. On sun-lit days, seagrass beds are magical places, with dappled light and the sun’s flickering rays highlighting the constantly swaying seagrass blades. Small fish dart amongst them and there is always the opportunity of a chance encounter with other fascinating marine life, including rather docile small-spotted catsharks.

A report released in March 2021 confirmed a catastrophic decline of seagrass meadows had been observed in the UK, with more than 90% of the Nation’s seagrass meadows lost in the last century or two. This said, moves are underway to look at how seagrass beds can be actively restored in Scotland’s coastal waters and elsewhere around the UK, recognising the importance and value of this essential marine habitat.

Project Seagrass aims to restore 30km2 of seagrass across the UK by 2030, and in 2020 they planted the final seeds in the two hectares of seagrass that represents the UK’s largest restoration project to date.

Education is a key tool in the protection of seagrass meadows, and there is ongoing work looking at mooring systems that reduce the physical impact that boating activities have to these habitats. Seagrass is recognised as a Priority Marine Feature by Marine Scotland, as beds are “functionally important, biodiverse, sensitive, slow to recover and if lost completely may not recover.” This recognition, coupled with seagrass being listed as a threatened and declining habitat by OSPAR, means that seagrass has fortunately been afforded fisheries protection in many Marine Protected Areas.

By protecting seagrass areas, such as those within the Lamlash Bay No Take Zone and Arran’s MPA, we can hopefully begin to ensure a better future for these special underwater meadows, whilst also presenting an opportunity to mitigate climate change.

Seagrass in shallow, sunlit waters. Photo credit Howard Wood