Image credit @Neil Garrick-Maidment, The Seahorse Trust
England’s seas support some of our most important and sensitive marine habitats and species, many of which are protected within marine protected areas (MPAs).
This includes seagrass, an important habitat for some of our most fascinating marine species, the seahorse and the stalked jellyfish.
Both depend on seagrass a marine flowering plant, which forms underwater meadows within the shelter of shallow, protected bays.
Understanding how marine non-licensable activities (mNLA) interact with seagrass and the species it supports is essential for informing future management decisions in MPAs and helping to protect them for future generations.
Seahorses
One of our most intriguing marine species associated with seagrass meadows is the seahorse.
Seahorses wrap their tails around seagrass to anchor themselves while feeding, sheltering and breeding. England's waters support two species of seahorse, the spiny. or long snouted seahorse (Hippocampus guttulatus) and the short snouted seahorse (Hippocampus hippocampus). Both species are protected under UK wildlife legislation.
Stalked jellyfish
Another less well known but nationally important species that can be found in seagrass beds and other shallow-water habitats in the UK, is the stalked jellyfish.
Not all jellyfish drift with the ocean currents, and unlike the free-swimming jellyfish most people are familiar with, stalked jellyfish are found attached to vegetation or algae and spend much of their lives fixed in one place, stalked jellyfish are rare and have specialised habitat requirements.
The UK is home to a number of species including the St. John’s stalked jellyfish (Calvadosia cruxmelitensis) and the kaleidoscope jellyfish (Haliclystus octoradiatus).
Stalked jellyfish on seagrass, Plymouth Sound image credi @Paul NaylorThe value of seagrass
In the UK, we have two species of seagrass, the common eelgrass (Zostera marina) and dwarf eelgrass (Zostera noltii). Seagrass beds are among the most valuable coastal habitats in the UK as they stabilise sediment, improve water quality, store carbon, provide nursery areas for commercially important fish species and support a wide range of marine life.
Seagrass is gaining global recognition for its environmental importance, with Blue Planet III showcasing how these underwater meadows help sustain life on Earth by generating oxygen and supporting marine biodiversity.
Common eelgrass bed, Studland Bay, credit @Paul NaylorImpacts of marine recreation
Seagrass habitats are vulnerable to physical disturbance because their roots and rhizomes lie close to the seabed surface. Anchoring, in particular, has been found to have a significant impact on this habitat. Anchors and anchor chains can disturb, uproot and damage seagrass plants during deployment, while vessels swing at anchor and during anchor retrieval. Repeated anchoring can create bare patches known as anchor scars, fragmenting seagrass beds and reducing their ability to recover.
Healthy seagrass habitats are essential for supporting seahorse and stalked jellyfish populations. Damage to these habitats can therefore have knock-on effects for the species that rely on them. Fragmentation and habitat loss can affect the distribution and survival of both species by reducing suitable attachment surfaces for stalked jellyfish, and the feeding opportunities, shelter and breeding habitat available to seahorses.
Recovery through management
Evidence from Studland Bay Marine Conservation Zone has shown encouraging signs of seagrass recovery following the introduction of a voluntary no anchor zone and the installation and use of advanced mooring systems also known as eco-moorings. Monitoring has identified new areas of seagrass growth and reductions in the size of previously recorded anchor scars. Learn more: Studland Bay seagrass shows dramatic recovery as MMO backed eco-moorings prove effective.
These findings demonstrate how targeted, evidence-led management measures can support habitat recovery while allowing people to continue enjoying the marine environment responsibly.
Have your say
MMO is currently seeking additional evidence on the impacts of mNLA on birds, benthic habitats, reef, and seagrass. If you have relevant research, monitoring data, reports or observations, we ask you to respond to our current call for evidence and respond before it closes on 25 November 2026.
By sharing information, you can help improve our understanding of these impacts and support the effective protection of England’s seagrass beds and associated species that rely on them.
For more detailed guidance on how to contribute, why this is important and the types of evidence that we find useful, please visit our previous blog: Share your evidence on the impacts of recreational activities in England’s marine protected areas (MPAs) – Marine Development Blog
If you require support completing our survey or submitting evidence, please let us know: conservation@marinemanagement.org.uk
seen at 10:46, 5 November in Marine Development Blog.