Geography B, Dynamic Planet, Unit 7: Oceans on the Edge (Revision to A*!)

Revision material that I got full marks on my exam for! Hope you like it.


Coral Reefs, Coasts, food webs, marine pressure case study, coastal mangment, global oceans managment.

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Preview of Geography B, Dynamic Planet, Unit 7: Oceans on the Edge (Revision to A*!)

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Unit 7: Oceans on the Edge
What different types of marine ecosystems are there and where are they located?
The distribution of marine ecosystems globally
Marine Ecosystem ­ Coral Reefs & Mangroves
Coral Reefs
Features of Coral Reefs:
Found in tropical waters (24°C - 26°C)
Found close to the shore (as they need shallow water of 25cm or less to ensure lots of light)
Provide home to over a quarter of all known species of fish.
Uses of coral reefs for nature:
Breeding zones for fish
Homes to fish safe from predators
Carbon store
Make oxygen
Uses of coral reefs for humans:
Provide breeding place for aquatic fish for the aquarium trade.
Major attraction for tourists
Provide protection to coastlines from erosion.
Shoreline protection from storms and tsunamis (reduce wave power)
Education and research ­ Medicine, learn about marine life
Source for jewellery
Natural threats:
Climate Change ­ More Carbon Dioxide means that the sea gets warmer as water absorbs CO2, meaning that it
gets warm itself. Warmer oceans lead to coral bleaching when algae are unable to survive and this upsets the
feeding cycle of coral. + Coral ecosystems become more vulnerable to bleaching + coral reef islands such as
Maldives would be completely submerged due to rising sea levels due to expansion.
Local warming can take place with events such as El Nino. This also causes coral bleaching.
Hurricanes produce huge waves and heavy rainfall which increases siltation. The sediment covers the coral
reefs, meaning they don't get enough light and die. This upsets the feeding cycle of coral.
Human threats:
Destructive fishing methods such as blast fishing (explosives).
Aquarium trade can also upset the feeding cycle of coral unless carefully controlled.
Population increase means that in many tropical areas where people are extremely poor people will migrate to
the coast to earn a living by fishing to feed their families, this puts pressure on the ocean life.
Coral Mining for sand and lime for urban development as coral is often the only local building material in
undeveloped countries.
Coastal development. Building works disturb the land and cause soil erosion. The soil then ends up in sea and
clouds the water, so less sunlight is able to reach the coral, so the coral dies.
Tourism ­ waste/sewage from hotels, demand for reef jewellery, and damage from guide boat anchors.
Global Warming due to people putting more greenhouse gases into the atmosphere, causing all reasons for
climate change.

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The distribution of coral reefs is very uneven
Most of those at high risk are in the Far East
There are very few low risk reefs in the Caribbean
Mangrove Swamps
Features and distribution of Mangrove Swamps:
Found in estuaries (A river mouth that is wide and experiences tidal conditions) and long marine shorelines.…read more

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Food Webs
A food web is an interconnected chain of animals showing their mutual interdependence.
There are relatively low numbers of top carnivores compared with the number of pray that they feed on.
This is because top carnivores use high levels of energy when chasing their pray so must ear large
numbers of pray to stay healthy. The aquatic plants and algae consume CO2 to produce oxygen, therefore
their lose would also have an effect on global temperature.…read more

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Bleaching due to increasing temperatures.
Melting of ice = sea-levels rises, flood risks, light can't get far, salty water into freshwater environment
Marine Pressures - St. Lucia
Local Pressures:
Tourism is the main industry (45% of GDP). Waste/sewage from hotels, demand for reef jewellery,
and damage from guide boat anchors.
Growing population ­ coastal development causing siltation, waste disposal.
Overfishing and unsustainable fishing ­ not rich enough to buy equipment for deep water fishing
so fish at the coral reef.…read more


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