Solent European Marine Sites (SEMS)

Concerns about disturbance and pollution

Worldwide, ports, industry, housing and associated infrastructure have crowded onto estuaries that were previously quiet marshy areas, the preserve of birds, invertebrates and fish; places of peace and beauty. In many cases abroad, the loss of habitat, increased pollution and disturbance has destroyed these valuable environments, requiring major regeneration programmes. On the Solent, we have been fortunate enough to have sufficient Conservation Law and management initiatives in place to safeguard our coastal conservation sites, habitats and their species. Despite the protective legislation these areas are under great pressure.

Bembridge Harbour and the Duver Marina

The Solent European Marine Sites (SEMS) is the collective name for the areas of conservation importance around the Solent. SEMS also includes Marine Protected Areas below Mean High Water designated as Special Areas of Conservation (SACs), which protect habitats, and Special Protected Areas (SPAs) which protect birds and their associated invertebrate communities. The SEMS area lies between Hurst Castle and Chichester Harbour, including sites on the north shore of the Isle of Wight. The legal framework for the management of European Marine Sites can be found in Section 38 of the EU Habitats Directive and is transposed into UK law as the HabsRegs (updated, 2017).

SEMS management includes our smaller Solent estuaries, such as the Lymington and Medina Rivers, which are also designated as Ramsar sites. The Ramsar Convention covers the ecological fitness of estuarine habitats and species as a whole. (This was an early international environmental Convention, which was signed at Ramsar, Iran in 1971, and was a major step forward in the protection of key estuarine and aquatic sites worldwide,
particularly for migratory birds.)

Responsibility for these sites lies with the SEMS management and stakeholder group. Advised by Natural England and with a secretariat provided by Solent Forum ( they produce a comprehensive annual report which assesses the ecological fitness of, and threats to, each SSSI component of the SEMS sites. Any actions required are taken forward by the Solent Forum Natural Environment Group. The varied nature of the sites and the many Local Authorities involved requires the co-operation of many stakeholders. Solent Forum provides the secretariat which pulls this all together – no mean task, and one carried out by a small, key and capable team.

At the time of writing, the SEMS management report for 2020 is in draft form and can be found at Information continues to be added. In brief – this year’s assessment of the SAC found that although the coastal lagoons were considered to be in ‘favourable condition’, other features, including the estuaries have been found to be in ‘unfavourable condition’. The reasons for this unfavourable assessment as listed in the draft report are:

  • Elevated nutrient levels (see below)
  • Low quality of invertebrates in subtidal sediments
  • Elevated contaminants, mostly TBT
  • Continued decline in extent of saltmarsh
  • Decrease in intertidal and subtidal seagrass compared with their historic extent

An updated, more detailed method of assessment will be used in 2021.

Regarding the condition of the SPA (Birds), there is concern due to the proliferation of housing development within a couple of hours’ drive of the Solent which has led to increased recreational pressure on our coastal habitats. Dog walkers, canoeists and more recently, paddleboarders seek out and disturb areas which were previously inaccessible such as creeks in saltmarshes. Drones, although occasionally used by the government agencies for scientific purposes, mimic a predatory hawk and cause alarm and disruption among nesting and feeding waterfowl and waders, frequently resulting in the loss of a brood.

Godwits feeding in a protected Solent estuary

Due to increasing concern about disturbance to these habitats, particularly to the saltmarsh, the responsibility for wardening and education has been managed by Bird Aware Solent ( with a system of rangers who engage with the public, educating and informing, and explaining the dangers of disturbance on these fragile habitats.

In January 2020, a new large SPA was designated, covering the coastal area between Dorset and Sussex and including the whole of the Solent. Although it will be managed to safeguard the habitats of all migratory waterfowl and waders it is designated specifically to encourage the recovery of the Tern population.

The Solent Protection Society (SPS) is particularly concerned about the increased phosphate and nitrogen load in Solent waters and their effect on the biota. Both chemicals cause eutrophication (chemical enrichment of the water) which stimulates the formation of large green mats of algae. These mats mostly occur in hot weather and are very damaging, depriving habitats of oxygen and killing dependent species. SPS is pressing both Southern Water and the Environment Agency for more transparent and frequent reporting of outfall monitoring. There is more information regarding this SPS Council initiative in another part of this Newsletter.

The Solent Protection Society Mission Statement includes the words – “The Solent Protection Society exists to ensure the ecological and environmental well-being and wise management of the Solent area.” These words chime well with the strategy of the Solent European Sites management team. Their job is a difficult one. Modern day pressures from recreational activities and pollution from housing, industry and farming on these precious areas of saltmarsh, maritime woodland, coastal lagoon and shingle are relentless.

Regarding disturbance, the 2020 SEMS report saw a relatively stable situation, although this is probably temporary. The effects of the recreational pressures manifest on the release of the Covid 19 lockdown will be included in next year’s report.