From the Menai Strait to Milford Haven: new evidence to help protect Wales' marine wildlife
From Milford Haven to the Menai Strait, new evidence is helping unlock a clearer path to protecting some of Wales' most important marine habitats.
Detailed investigations into three protected marine habitats have provided new insight into the pressures affecting marine wildlife and identified actions that could help improve conditions for recovery. The work focused on sponge communities in the Menai Strait and Conwy Bay, horse mussel reefs off the Llŷn Peninsula, and the Milford Haven maerl bed – the only known living maerl bed in Wales.
All three areas are designated as Special Areas of Conservation (SACs), meaning they contain habitats and species that are important at a European level. Together, they support rich marine life and form a key part of Wales' network of Marine Protected Areas.
Natural Resources Wales (NRW) carried out the investigations to understand what is driving declines in the habitats and to identify where action could make the greatest difference.
The studies found that no single pressure explains the changes being seen. Instead, a combination of factors is affecting these habitats, including nutrient pollution, sedimentation, physical disturbance of the seabed, invasive species and climate change. While the pressures differ between sites, the findings provide valuable new evidence to help target conservation action and support recovery.
In Milford Haven, the investigation found that historic sedimentation and physical disturbance are likely to have contributed to the decline of the maerl bed. It also identified ongoing barriers to recovery, including nutrient enrichment, suspended sediment, invasive slipper limpets and wider water quality pressures.
In Pen Llŷn a'r Sarnau, the horse mussel reef investigation highlighted the combined effects of historic physical disturbance, changing environmental conditions and climate-related pressures, while identifying priorities for future monitoring and management.
In the Menai Strait and Conwy Bay, the sponge investigation provided new insight into the environmental changes affecting protected sponge communities, helping to inform future monitoring and management of these habitats.
The investigations were commissioned following NRW's latest assessments of Wales' Marine Protected Areas. Published last year alongside the State of Natural Resources Report (SoNaRR 2025), the assessments highlighted a number of protected habitats and species where further investigation was needed to better understand the reasons for declining condition.
Andrea Winterton, Marine Services Manager for Natural Resources Wales said:
“We've known for some time that these habitats are facing a range of pressures, and monitoring has helped us understand how their condition is changing. These investigations take that a step further by improving our understanding of what's driving those changes and where action can have the greatest impact. The studies form part of NRW's wider work to improve the condition and resilience of Wales' marine protected areas and support action to address the nature and climate emergencies.
“By identifying the pressures that are holding these habitats back, we have a better opportunity to support their recovery and safeguard the rich marine life they support. They form part of the natural heritage that makes Wales unique, and the findings will help us work with partners to protect these special places and build their resilience for the future."