Oceans

Geog Edexcel B

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  • Created by: Rebecca
  • Created on: 07-05-11 14:30

 Define Ocean

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A large body of salt water, consituting 70% of the Earth's surface area

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What are coral reefs and where are they found?

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They are living organisms called coral ployp that secrete calcium carbonate.

They are found near the tropics in shallow, warm, salt water (24-26C)

Some examples of locations are:

  • South Pacific Ocean
  • Australasia
  • Caribbean
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What are the uses of coral reefs?

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  • Fish: 4000 species, 25% of the world's fish
  • Aquarium trade: seahorses and exotic plants
  • Shoreline protection: natural barrier against coastal erosion
  • Tourism: Caribbean gets helf income from tourism
  • Research and education: e.g. marine biology
  • Others: medicines, jewellery, building materials

You could use the acronym: FAST RO

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What are the threats to coral reefs?

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  • Tourism: (find out more later)
  • Overfishing: damages ecosystems and dynamite damages coral
  • Pollution: sewage, farming and tourism causes water pollution, increasing black band coral disease
  • Climate change: (find out more later)
  • Aquarium trade exploitation: disrupts ecosystems
  • Boats: anchors damage coral and boats can sail into reefs

You can use the acronym: TOP CAB

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How is the Southern Ocean marine ecosystem disrupted?

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  • Habitat destruction: beam trawlers, dynamite and oil slicks damage habitats.
  • Pollution: oil leaks are tosix and sewage, fertilisers and organic waste deplete oxygen through eutrophication.
  • Overfishing: the number of krill has decreased by 80% since 1980 for use as bait in fish farms and in Omega 3 tablets. They are a keystone species so the rest of the ecosystem relies on them.

All three mean living organisms will have to migrate, increasing competition elsewhere. This means less food will be available so they will become weaker and may even become extinct. This also reduces biodiversity.

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How can climate change impact marine ecosystems?

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  • Temperatures increase causing coral bleaching because algae die
  • Coral can't survive if temperatures exceed 26C
  • Melting glaciers affect the salt concentration which also affects currents so some parts e.g. Southern Ocean may become warmer and other parts may become coller, disrupting ecosystems.
  • Oceans expand in warmer temperatures, affecting ecosystems
  • There are more storms and waves become stronger so coral is more easily damaged
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How does tourism affect the coral reefs?

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St Lucia is in the Caribbean, near Martinique and Barbados

Coral reefs are located primarily around the Northeast and Southeast coasts

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ST LUCIA CASE STUDY

  • Where is it?
  • How are the reefs distributed?
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Direct:

  • Suncream changes pH of water
  • Snorkelling and trampling damage coral
  • Sewage and waste pollute water

Indirect:

  • More demand for seafood increases overfishing
  • Construction of hotels uses limestone
  • Beach enhancement means sand ruins coral
  • Concrete along the coastline increases run off so waste water pollutes the sea, damaging coral reefs
  • Pontoons (floating hotels) are built which can damage coral

Can't think of any acronyms so let me know if you can!!

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What are the growing localised pressures in St. Lucia?

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  • Population is increasing at 3% each year, producing more waste water
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  • Locals don't have deep sea fishing equipment so instead rely on exploiting the continental shelf, causing overfishing
  • The fishing methods are damaging because they chase fish and place pots on the coral
  • Banana plantations cause deforestation, increasing the runoff of waste water and causing siltation
  • Tourism creates half their income so trampling and snorkelling cause problems.
  • 20% live below the poverty line so hunt wildlife and harvest mangroves. This is damaging because mangroves remove pollutants, produce nutrients and provide safe fish nurseries.
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How are fish stocks managed in the North Sea?

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EU Common Fisheries Policy

  • Restrictions on mesh size to allow young fish to breed and reduce bycatch
  • Quotas on fish caught and time spent fishing to reduce overfishing
  • Focus on whole ecosystem, making it more effective
  • Marine reserves allow fish to reproduce and increase stocks
  • Further research into fishing effects on the North Sea

Although this is sustainable, it causes conflict between fishermen who lose their income and environmentalists who support the scheme. It's also expensive because you must compensate the fishermen for their lose of earnings.

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How are the reefs managed in St. Lucia?

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Soufriere Marine Management Area

  • Coastal zoning: some areas used to fishing, diving, anchoring boats etc. and some are protected
  • Fishermen are provided with better boats to go beyond the continental shelf and refrigerators to reduce the waste of fish
  • Local people are trained and educated to manage the scheme, making it more sustainable
  • The scheme is self-funded because fees from divers and yacht owners fund the rangers who police the scheme

Since the scheme was implemented, numbers sizes and diversity of fish species have increased. However, the area is very popular with tourists which poses many threats. Rapid development also threatens the success of the scheme.

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How are the oceans managed globally?

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The Law of the Seas (UNCLOS)

  • 40% of the ocean is under this law
  • Pollution is limited
  • Different zones are set up to restrict usage
  • It prevents some nations taking an unfair share of the ocean

Global schemes can be less effective as they're often optional so not all nations agree to the regulations.

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