The Southern North Sea extends from Flamborough Head in the north to Dover in the south. Water depths are less than 50 m and most of the region is well mixed by tides and wind throughout the year. The coastline is varied with extensive areas of intertidal muds and sands and soft cliffs. The main offshore habitats are large expanses of sands and coarser sediments. There are large seasonal variations in sea-surface temperature, ranging from 4 °C in winter to 19 °C in summer.

Climate change

Sea level is rising, increasing the risk of coastal erosion, flooding and loss of intertidal habitat due to ‘coastal squeeze’. This is a particular concern in this region as the land is sinking and the coasts of south-eastern England are low lying. The coasts are generally formed of soft sediments which are susceptible to erosion.

Sea temperature is rising and has resulted in changes in plankton production. Production has increased and the spring bloom is starting earlier, but the species present have not changed and are typical of shallow coastal areas. The increased growth in coastal waters is also related, in part, to coastal nutrient enrichment. There has been a small decrease in salinity, which may reflect an increase in freshwater run-off from the major rivers entering the region, although our confidence in this explanation is low.

Maritime economy

This region has major gas fields, and the oil and gas sector provides the greatest economic contribution. Important gas pipelines connecting the gas fields to Europe come ashore at Easington and Bacton. Subsea caverns and depleted gas fields provide good potential for storage of natural gas or CO₂. There are wind farms at Lynn, Inner Dowsing, Scroby Sands, and Kentish Flats and further sites are being developed so the value of the renewables industry will increase. Cooling water abstraction has significant value owing to a number of nationally important coastal power stations.

Grimsby and Immingham in the Humber Estuary and London in the Thames Estuary are two of the busiest UK freight ports, benefiting from proximity to markets in Europe. 26% of UK dredged material disposal sites are associated with the port developments in the region. The region contains the UK’s most important marine aggregate resources. Licensed areas off the Humber and East Coast regions and the Thames Estuary, provide almost half of all marine construction aggregate, most to London. The region has the highest proportion of coastal defence (32%) and flood protection schemes (33%) in the UK and further development in response to rising sea level will add to the existing pressure on intertidal sediment habitats. Recreation is also important supporting both the local population and numbers of visitors in activities such as leisure boating and bird watching at nationally significant wetland sites.

Fishing pressure

Assessed commercial fish stocks are either not at full reproductive capacity or are not being harvested sustainably. With the exception of haddock and saithe, the state of demersal fish communities appears to be improving, shown by evidence of increasing species richness and evenness. However, smaller and opportunistic fish now dominate the fish community. Salmon and eel populations in estuaries are deteriorating.

The coastal and seabed sediment habitats are severely impacted by the range and distribution of human activities that are taking place in this region; rocky habitats are impacted to a much lesser extent. Bottom trawling activity, particularly near the coast, is a major pressure.

Other issues affecting status

There have been significant changes in the populations of grey and harbour seals. Harbour seals are continuing to decrease following earlier disease outbreaks although the cause of the continuing decrease is unknown. Dolphins, whales and porpoises are considered to be in good condition although there are some concerns about the level of fisheries by-catch of harbour porpoise. Some waterbird populations have declined and this has been linked to reduced food availability possibly due to pressure from shellfisheries.

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