Revision Notes
What you need to know
1. Threats to the ocean
2. Ecosystem change
3. Increasing exploitation
4. Sustainable management
How and why are some ecosystems
threatened with destruction?
 The term ecosystem describes a grouping of plants and
animals that is linked with its local physical environment.
 The oceans, covering two-thirds of our planet, are home
to marine ecosystem communities composed of fish,
aquatic plants and sea birds- as well as tiny but very
important organisms such as krill and plankton.
 HINT: make sure you are able to name some values of the
Oceans e.g. its uses and value to human and animal life.
Unsustainable Uses
 The way we use Oceans is becoming UNSUSTAINABLE this
means we aren't treating/using it in a way that will preserve it
for future generations. Within the oceans here is a natural
balance between all life- these relationships form the FOOD
WEB.
 It is also important to consider the NUTRIENT CYCLE which
is the movement and re-use of important substances e.g.,
nitrogen.
 DISRUPTION’S TO FOOD WEBS the main three disruptions
you need to understand are:
1. Overfishing
2. Eutrophication (caused by pollution)
3. Siltation (sedimentation)
Climate
Change
 Climate change also disrupts the oceans.
Warmer Water
• Fish in tropical seas could face
famine
• Food shortages then develop
throughout entire food webs
More acidic water and
bleaching
• Carbon dioxide dissolves in water to
form carbonic acid
• Small rises in acidity can seriously
damage coral reefs, which then
appear bleached after losing their
vibrant colour
Higher Sea Levels
• Melting ice sheets on land masses
will bring sea-level rises
• Coastal marine ecosystems such as
mangrove swamp or UK salt marshes
would become permanently
submerged and unique maritime
communities might disappear
altogether
How should ecosystems be managed
sustainably?
 There are three ways that marine ecosystems can be
managed and that is again, as with the other units, at a
LOCAL, REGIONAL and GLOBAL SCALE.
Local Scale
 Managing coral reefs:
 Reefs are made of living animals, each piece contains polyp.
They are part of a large colony of marine life. The polyp are
skeletal creatures that form coral in clear, warm and
sunlight seas.
 Coral reefs are home to ¼ of the world’s fish species. It also
acts as natural barriers that protect the coastline from
erosion. They are also great for tourism. However there are
sustainability issues that come with this.
Your case studies are the Great Barrier Reef, the Coral
Triangle, and the Soufriere Marine Management Area
Coral Reefs Under Threat
 The location of the SMMA, which stands for the Soufriere
Marine Management Area is located in the town of Soufriere
in the west coast of the Caribbean island of St.Lucia.
 The SMMA was formed in 1992 to protect the marine wildlife
and reefs immediately surrounding the town.
 It brought together the following people, who would normally
come into conflict:
 The local town council
 Local hotel owners
 Water-taxi owners
 Dive businesses
 Fishermen
 Marine managers
 Overall the SMMA has been successful as a model of
sustainability.
 As a result, some of the best dive sites in the Caribbean are
found in the waters of the SMMA.
Result:
Some problems –
• the area has become so popular that the marine environment is threatened by mass tourism
• rapid development in Soufriere encourages siltation and pollution
But also positives –
• the numbers, sizes and diversity of fish species has increased
• many stakeholders are now involved in marine conservation
Regional Scale: Managing the
North Sea
1.
Such as:
1. ensuring that the mesh of nets won’t catch
undersized young fish
2. limiting the number of hours and days that fishing
boats can operate each year
3. quota management
4. discard management
5. setting up marine reserves which protect all species
6. further research into how fishing affects the whole
ecosystem
The EU Common Fisheries Policy has
tried to bring back fish stocks from
catastrophically low levels in the North
Sea.
2. Fishermen want as large a quota as
possible but marine scientists argue that
only ‘no fishing’ marine reserves will save
species like the cod. But this is expensive
as it means you have to pay fishermen
not to fish!
3. Additionally, global warming is playing a
part. Cold water species of plankton
have been replaced by warm water
species, changing the food available for
baby cod. Furthermore, as the North Sea
warms, cod will migrate to Arctic areas.
Global Scale
 Global actions are needed to tackle pollution and to
save threatened species from overfishing and
extinction. International Organisations play a large
role in ensuring that the oceans are protected.
 The United Nations Food and Agriculture
Organisations regulates the management of deep sea
fisheries. Other examples include IWC, UNCLOS and
CITES (see next slide for more details)
 Individuals around the world can also ‘do their bit’ by
changing their shopping habits to ensure that we only
buy sustainably sources fish and buy ‘dolphin friendly’
tuna. (Think about what came out of your work on
your DVDs)
IWC: The International Whaling Convention was
established in 1946 to oversee the management of the
whaling industry worldwide. In 1986 it issued an
indefinite ban on commercial whale hunting.
UNCLOS: The United Nations Convention on the Law
of the Sea addresses the main sources of ocean
pollution – land based/coastal activities; continental
shelf drilling for gas and oil; seabed mining; ocean
dumping; and pollution from ships.
CITES: The Convention on International Trade in
Endangered Species of Wild Fauna and Flora gives
global protection to all of the great whales
Far More Difficult Problems
 To tackle on a global scale is the growth of the ‘Pacific
Garbage Patches’.
 These are enormous rubbish-strewn regions of the
north Pacific. The currents flow creates giant pools of
‘rubbish soup’.
Practice Questions
1. Using examples, describe the threats facing marine ecosystems
(6) Foundation
2. Using named examples, explain the short and long-term threats
facing marine ecosystems (6) Higher
3. Describe the type of area a coral reef might be found (2)
4. How can an undisturbed coral reef support human activities?
(2)
5. How could an increase in demand for one type of fish impact on
the food chain? (6)
6. Explain how the change in ocean’s currents could impact
marine ecosystems? (6)
7. Explain why the worlds oceans are under threat (4)
8. With reference to an example, explain the problems and
successes of sustainable fishing (4)