Our seas are priceless. Up to half of the UK’s wildlife is found in the ocean and new and wonderful discoveries are being made all the time. The seas around our shores are home to an amazing variety of animals, including dolphins, turtles, seals and sea horses as well as the mighty orca- the killer whale. We even have deep-sea coral reefs- rich and diverse like those found in the tropics.
A combination of rising sea levels and rising global temperatures are threatening thousands of hectares of Britain’s shoreline and vital wildlife habitats. As climate scientists predict that sea level rise will accelerate it is estimated that 10,000 plants and nature reserves will be at risk of inundation. The projected impacts of climate change include :-
- Diversion of ocean currents. This may be particularly important for the UK as the warm Gulf Stream maintains a milder climate than would be expected at our latitude. Shifts in currents could alter geographic distribution of fish populations by varying temperature, salinity and nutrient availability.
- Increased frequency and intensity of storm events. This may damage coastal habitats and coral reefs.
- Shifts in composition and geographic distribution of ecosystems. These have potential impacts on biodiversity and fisheries.
- Melt-down of Polar ice caps. This will have subsequent impact on salinity levels and ocean temperatures- potentially reducing the temperature at the northerly and southerly latitudes.
- Sea level rise. This will result from the melt-down of ice caps and is considered to be the most significant and destructive impact of global warming.
The North sea is one of the world’s major fishing grounds, supporting a variety of commercial fish stocks. Pelagic fish taken are mackerel and herring, and demersal species such as cod, haddock, saithe and whiting are fished extensively. Bottom living fish, especially plaice and sole are also exploited. Some species are not taken directly for human consumption, such as Norway pout, sandeels and sprats, most of which are made into fishmeal for use in intensive livestock farming. Rapid technological advances made in recent years have allowed the efficiency of fishing fleets to increase, and numbers of boats employed in fishing have increased in recent decades. Many species such as herring, cod, skate and haddock have been so heavily fished that their populations have fallen to critical levels. If the natural balance is greatly upset by commercial fishing there will be far reaching consequences on marine ecosystems. The possible links between sandeel fisheries and the breeding failure of seabirds, especially arctic terns and kittiwakes are well documented.
Both natural and synthetic chemical compounds contaminate the marine environment. Chemicals enter it via several pathways :-
- Point-source discharges e.g. from sewage treatment works and oil rigs.
- Diffuse discharges e.g. from agriculture and shipping.
- Atmospheric deposition e.g. from waste incineration plants.
Chemicals are used by most industries at some stage in the production process and are often present in the finished product. The major contributors to chemical pollution in the marine environment are :
- Agriculture- conventional farming practices rely heavily on the use of agro-chemicals to prevent damage by pests and weeds. Widespread use of pesticides and herbicides inevitably leads to the contamination of streams and rivers which discharge to the marine environment.
- Chemical and pharmaceutical manufacturing. - Much of the UK’s large chemicals industry is situated at the coast. By-products and waste from production are usually discharged to the sea directly or via sewage treatment works. In 1987 12 billion litres of industrial waste drained through public sewers every day.
- Offshore oil and gas.- Offshore oil and gas production requires the use of hundreds of different chemicals , including lubricants, corrosion inhibitors, demulsifiers, biocides and surfactants. These are discharged to the marine environment in produced water and drill cuttings and directly from the rigs in washings.
- Transport. - most seagoing vessels , from cargo ships to yachts, use some form of antifoulant paint on the hull to prevent colonisation by marine organisms. Many antifoulants are designed to leach chemicals into sea water.
Chemical pollution can affect marine life at every trophic level. The impact on species’ biology are very complex and poorly understood, though some end effects are well documented, particularly on the reproductive system :
- Intersex is where an individual has both male and female intermediary characteristics. This has been found in high levels in some tiny crustacea in coastal waters. In UK industrialised estuaries males of bottom-dwelling fish such as flounder have synthesised the female egg yolk protein vitellogenin and developed egg cells in otherwise normal testes.
- Imposex is where an individual of a species has the sexual characteristics of the opposite sex superimposed on its own. This has been highly evident in the dogwhelk, where females have developed male genitalia as a result of exposure to the antifoulant tributyltin (TBT).
- Hermaphroditism is where an individual has both male and female reproductive organs. In 1998 4% of polar bears on two Arctic islands were found to be hermaphroditic- high PCB levels were found in their fat.
WHAT CAN BE DONE ?
More Marine Protection Areas should be set up with more effective protection for the UK’s marine wildlife, habitats and the people who depend on the sea for their living. A Marine Protected Area is similar to a nature reserve on land. It’s an area where human activities take place in harmony with nature. It provides food, shelter, breeding and nursery grounds for marine wildlife. It offers greater protection for species including dolphins, corals, sea horses and habitats such as grass meadows. It can also offer better protection from the impacts of oil pollution (3 of the world’s biggest oil spills occurred around British coasts), shipping and drilling for oil and gas.
A Fishing-Free Zone would greatly benefit our fish stocks. If fish are left undisturbed they regenerate themselves very quickly and efficiently. Fishing-Free Zones are relatively easy to enforce as by using satellite tracking we can throw a virtual “fence” around any area.
For further information please see the following web sites:-
