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REVISION
GUIDE
OCEANS ON
THE EDGE
Name:______
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1.
Why are the world’s coral reefs being threatened?
LO: Can you distinguish between human and natural
coral reefs
threats to the world’s
Keywords
Dead zones
Bleaching
Ecosystems that have collapsed
completely
Rising temperatures due to global
warming leads to coral stress which
makes the coral turn white
Why are coral reefs called the “rainforests of the oceans”
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Provides 25% of the world’s total commercial fish caught
Reefs grow with rising sea levels caused by climate change
Reefs attract tourists and therefore make money for countries
Source of medicine
Reefs protect the shore from storms, tsunamis and wave erosion
Supply tropical fish, sea horses and plants for aquariums
Educate people about marine life
Used to make jewellery
Provide lime used for cement and building
Natural threats to coral reefs
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Unusually strong waves such as those from a hurricane
Water temperature changes (El Nino)
Dramatic changes in saltiness of water
Predators, such as snails and crown of thorns starfish who kill the coral
Overgrowth of algae
Human threats to coral reefs
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Global warming
- Causes the bleaching of coral reefs
Pollution
Sewage, oil and toxic chemicals can kill reefs
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Power plants
Releasing hot water into the sea which kills organisms
Deforestation
– Causes erosion which clouds the water with mud
– Increases global warming
Destructive fishing (especially in LEDCs)
– Blasting with dynamite
– Cyanide poison
– Boats running aground, anchors
– Overfishing of reef species especially in the Far East
How do tourists threaten coral reefs?
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Threats to coral reefs
Natural
Human
Hurricanes
Global Warming
Water Temperature Change
Pollution
Dramatic changes in saltiness of
water
Power plants
Deforestation
Predators, such as snails and crown
of thorns starfish who kill the coral
Destructive Fishing
Overgrowth of algae
Tourism
Exam-style question:
• Explain, giving examples, why the world’s coral reefs are under threat.
(6 marks
2.
Unsustainable use of the ocean – case study: Krill
LO: To understand that overfishing (case study:krill), habitat destruction, and
pollution are examples of using the ocean in an unsustainable way.
Keywords
Eutrophication
Unsustainable
When pollution enters the ocean and
leads to a decrease in oxygen levels
may meet the needs of the present but
wont meet the needs of future
generations
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Case-study: Overfishing of krill
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Krill are tiny shrimp-like animals. They are a keystone species.
They eat algae and plankton and in turn they are eaten by whales, penguins
and fish.
Krill is under threat from global warming but also because of “suction”
harvesting which is the method fishermen use to collect huge quantities of
krill.
Krill is used in omega 3 health supplements and used to feed to fish in fish
farms
What happens when pollution enters the water?
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When pollution enters the oceans this leads to nutrient (food) cycles been
disrupted and nutrient overloading takes place. This is called eutrophication.
Dead zones are areas of the ocean where oxygen levels are very low.
Climate change adds to these dead zones as extreme storms leads to more
flooding and this puts more nitrates and phosphates (nutrients) into the
oceans.
What is an algae bloom?
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Fertiliser and sewage wash into oceans
This leads to the growth of toxic algae
Marine bacteria eats this algae.
When they die they sink to the bottom and decay
This uses up all the oxygen in the oceans
This leads to poisonous conditions which can kill worms and shellfish who live
at the bottom of the ocean and can even lead to humans eating poisoned fish
Climate change and the oceans
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Climate change will have direct and indirect impacts on the world’s oceans.
Direct impacts include:
– Effects of temperature increase will damage corals by bleaching
them.
– More pollution and siltation (mud) in the oceans due to extreme
weather.
- Melting of ice sheets will increase the amount of freshwater in the
oceans which makes the water less salty and less dense. This affects ocean
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currents which distribute heat in the oceans and the migration of fish will
be affected
Indirect impacts include:
- rises in sea level. Warmer water temperatures cause oceans to expand
(thermal expansion). Melting glaciers and ice sheets also add to the volume
of water in the oceans.
In the 20th century the oceans rose by an average of 15cm
By the end of the 21st century this rise could be between 20cm and 1 metre
Effects of a 1 metre rise in sea levels
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Coral reef islands like the Maldives or South Pacific Islands (Tuvalu)
would be submerged (covered by water).
Heavily populated deltas like the Nile or Ganges-Bramaputra would be a risk
from storm surges and floods. Supplies of freshwater would be
contaminated.
Low-lying countries like the Netherlands would be submerged unless they
have flood defences.
Number of environmental refugees would increase.(people forced to leave
their countries due to loss of jobs as a result of environmental problems)
Mega-cities like Mumbai or Lagos would be under threat as their water and
sanitation systems would be affected. People in shanty towns would be more
at risk of disease.
Many ports would be damaged – affect the economy of many countries
Exam-style question:
“Using examples, explain the impacts of climate change on either developed
or developing countries” (6 marks).
3.
Sustainable management of the world’s oceans
Local Case study : Lamlash Bay – Scotland
Problems:
-Over-fishing of some species has caused populations to crash, e.g. Cod
-Businesses have turned to tourism due to falling income from fishing and farming,
but activities like yachting, snorkelling and kayaking disturb wildlife.
-In the past untreated sewage flowed straight into the sea, laws no ban this
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-Deep seafloor is perfect for military testing , but an accident would devastate the
ecosystem
-Much of the Firth of Clyde has been over-fished, especially Lamlash bay where
scallops thrive.
• Scallops are an expensive seafood delicacy
• Scallops are harvested using dredging machinery made of chains and rollers
which scours the sea bed.
• Dredging has destroyed Maerl – an important nursery for cod, haddock and
plaice
Solution: Lamlash Bay- no take zone
• Established by the Scottish government in 2008
• All fishing in the area is banned
• Scientific tests will be carried out to monitor the seabed, to see if it can
regenerate naturally
Conflict:
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For: Many outsiders have moved to the area (for the sea views) – some would
like to see the area free of commercial activities
Against: Local fishermen would rely on the Clyde for their livelihood
International Case study – St Lucia
• Sustainable management - meeting the needs of the future without
sacrificing the ability of future generations to meet their needs. This
involved protecting the environment but also helping local people make a
living
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Finite resources – resources which will run out one day for example oil and
coal
How does sustainable management work?
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Using fishing equipment which doesn’t damage coral reefs
Don’t take out too many fish or shellfish
Allowing poor people to take enough fish for their own needs (subsistence
needs)
Letting local people have a say in how the area is used.
Why did the need to protect St Lucia?
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St Lucia is a volcanic island so most of the population live along the coast.
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Most of the fisherman are subsistence fishermen who don’t have boats for
deep sea fishing so they fish by placing pots on coral reefs or chase fish into
nets by throwing rocks into the water.
The tourist industry has grown quickly in St Lucia leading to pollution and
waste disposal problems. More tourists are snorkelling, diving and yachting.
St Lucia is very poor (LEDC) and many have no jobs so they need to harvest
mangroves for charcoal, hunt wildlife and catch fish to survive.
Forests are cut down for banana plantations which leads to heavy siltation
(mud runs in the oceans) especially during storms
Why were their conflicts?
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The areas of St Lucia which needed to most protection were the coral reefs
of Soufriere and the mangrove forests of Mankote. The community needed
to be involved in stopping this.
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There were conflicts in Soufriere between fishermen, divers, snorkellers
and yacht owners. Why?
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In Mankote there was lots of over-hunting and overfishing as well as rubbish
disposal and spraying of insecticide to get rid of mosquitoes. The mangroves
are important natural areas and also provide the local communities with fish,
wood, charcoal, honey and salt.
What did they do to solve the problem?
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In 1986 St Lucia made 19 areas into Marine Reserve Areas (MRAs). These
are areas that cannot be fished.These included coral reefs, turtle breeding
grounds and mangroves.
Fishing Priority Areas (FPAs) were also created where fishing could take
place.
The boundaries between these weren’t clear so conflict (disagreements)
occurred.
In 1992 this problem was solved by creating a
Soufriere Marine Management Areas (SMMA).
This meant that creating clear zones instead of just creating areas which
weren’t clear.
For this project to work all stakeholders had to be involved in the planning
i.e.
-the local town council
- water taxi-owners
- dive businesses
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- fishermen
- marine managers
Has this been successful?
Problems:
- Difficult to get everyone to agree (creating a conservation area
means fishermen cant fish there)
- Fishing community angry about seeing divers in this area
- Local people had to be trained and educated to manage the scheme
which costs money.
- Area has become so popular that mass tourism is now a threat. This
can create pollution.
Positives:
- numbers, size and diversity of fish increased
- Many stakeholders involved in protecting the marine environment
- Fees from divers and yacht owners now fund the scheme
- In Soufriere the fishermen were provided with modern boats and a refrigerated
ice house to improve fish processing.
- In Mankote land was set aside for locals to get wood for fuel and charcoal. They
were also given a piece of land to grow vegetables
- Ecotourism was also encouraged to bring in extra money.
Exam style question:
With reference to an example, explain the problems and successes of
sustainable fishing (4 marks)
5. Are there any international laws to
protect the oceans?
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The LAW OF THE SEA prevents certain nations from taking an unfair
share of the ocean’s wealth
This law was signed in 1994 at the Third Law of the Sea Conference
(UNCLOS).
40% of the ocean falls within this law. This is done by having:
Territorial areas (12 mile limit) controlled by specific countries
Contiguous zones (24 mile limit) for scientific purposes
Exclusive Economic Zones (200 mile limit) for economic activity, scientific
research and environmental conservation
Continental shelves where any country can explore
and use the sea without breaking any laws.
The other 60% of the ocean is free for anyone to use.
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UNCLOS tries to stop pollution from:
– Land-based coastal activities
– Drilling the ocean for oil and gas
– Mining on the seabed
– Dumping rubbish into the ocean
– Pollution from ships
The International Whaling Commission banned whaling for commercial
purposes form 1982. Since then it has establish whale sanctuaries in the
Southern and Indian Oceans
Exam-style question:
Using an example explain why marine environments are so difficult to protect
(6 marks)
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