England’s marine environment continues to come under pressure from man, as we increasingly seek to make use of the goods and services which our seas provide.
Some of man’s activities in the sea have been taking place over many years such as commercial fishing and sewage disposal, whilst others are on the increase, for example wind-farm development and other renewable energy schemes. Depending on the nature, scale and location of these activities, and the degree to which they are controlled, the marine environment can easily be damaged. Sometimes damage can occur through the cumulative effects of multiple pressures, rather than from single activities.
The marine environment is at risk from pressures operating at local, regional, or global scales.
Climate change is already seen to be impacting upon the marine environment and will continue to trigger changes in biological, chemical and physical processes. Such changes can affect the ‘resilience’ against other man-induced pressures. The main impacts are:
Find out more about climate change and how we are monitoring its effects.
Activities which can cause physical loss and disturbance of marine habitats would include:
Marine species (especially fish) populations can be threatened by both the intensity and the efficiency of commercial fishing. Some species are particularly vulnerable; generally those that are long-lived and only start breeding after a relatively long period of immaturity. Sharks, rays and skates, and many species of fish in deep water fall into this category. In addition, there can be unintended effects of fisheries such as by-catch that further reduce populations of key species.
Now over 90% of the big fish in the world’s seas have gone. The pressures from fishing have altered not just the size, the species present, but even the genetics of some species.
Since 1990, at least 70% of overall UK fish stocks have declined in their reproductive capacity and have been harvested unsustainably. The situation varies widely between species. In 2005, only 65% of assessed UK fish stocks (largely whitefish) were fished sustainably and only 35% of fish stocks around the UK were at full reproductive capacity. In 1998, UK vessels landed £137 million of cod and haddock (about 25% of UK landings by value), but this fell to just £70 million in 2002.
Find out more about sea fisheries
About 80% of marine pollution comes from land-based activities. Pollutants enter the sea through direct discharges of effluents, land run-off (mainly via rivers), or pollution from the air. Some pollutants introduced into the marine environment can have toxic effects and lead to obvious declines in species. For example, anti-foulant paint used on the hulls of boats caused severe damage to non-target species in the wider marine environment. Particularly noticeable was that female dog whelks, exposed to TBT, developed male sex characteristics.
Other pollutants have the potential to stimulate changes which degrade ecosystems and lead to adverse effects on habitats and species. Excess nutrients are a good example as this can lead to excessive growth of dense algal mats which blanket the seabed and foreshore. There is also concern about the masses of marine garbage far out at sea. Sea turtles can die from eating plastic bags mistaking them for jellyfish.
Sometimes marine incidents such as an oil spill from a ship can cause significant pollution to the marine environment. The MSC Napoli incident that occurred in January 2007, is one example. The grounding of this container ship resulted in pollution from oil impacting seabirds and a risk to the benthic environment. Natural England commissioned two benthic surveys and an analysis of the dead oiled birds as a result of this incident.
Natural England is a partner in the development of the Cefas* led PREMIAM (Pollution Response in Emergencies: Marine Impact Assessment and Monitoring) programme. The PREMIAM programme aims to provide a co-ordinated framework for marine monitoring following chemical or oil spills and will fulfill two objectives:
The development of marine assessment and monitoring guidelines (The PREMIAM Plan)
The development and maintenance of a network of scientific and logistical partners to deliver the plan (The PREMIAM Network).
* Cefas - Centre for Environment, Fisheries and Aquaculture Science
The introduction of aquatic species (knowingly or accidentally) to ecosystems outside their normal range and distribution can threaten native species and their habitats. For example, the marine non-native slipper limpet (Crepidula fornicata) introduced into England in the late 19th century from North America has successfully outcompeted native invertebrates.
Find out more about non-native species and their effect on the environment.