© Boardworks Ltd 2009 1 of 38 Coastal Ecosystems at Risk Coasts

© Boardworks Ltd 20091 of 38

Co

astal E

cosystem

s at Risk

Co

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Contents

Teacher’s notes included in the Notes Page

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Extension activity

Icons:

Types of ecosystems

Sand dunes, salt marshes, coral reefs and mangrove

Factors threatening ecosystems

Sustainable management


Key questions: Types of

ecosystemsTypes of ecosystems

What is biodiversity?

What different coastal ecosystems are there?

What is succession and how does it happen?

What are seres and where do different seres occur?

By the end of this chapter you should have considered these key themes and questions:


Biodiversity

Biodiversity is the number and diversity of all living things on earth. This variety of species encompasses a genetic diversity which it is important to protect. Huge biodiversity exists in the ecosystems found at the coast.

An ecosystem consists of a dynamic set of living organisms (biotic components) all interacting among themselves and with the environment in which they live (an abiotic component).

What is an ecosystem?


Coastal ecosystems


Succession


Succession and seres


Seres


Key questions: Sand dunes, salt marshes, coral reefs and mangroves

How do sand dunes form?

How do salt marshes form and why are they important?

Where are coral reefs found and why are they important?

What are mangroves and what role do they play in Bangladesh?


Sand dunes, salt marshes, coral reefs and mangroves


Study the map of the UK. Can you describe the distribution of coastal sand dunes? In which areas are they most sparsely and densely distributed?

What conditions do they need to form?

Sand dune ecosystems

Coastal sand dunes are dynamic accumulations of sand. In England, Scotland and Wales, there are approximately 800

km2 of coastal sand dunes.

lowland coast

prevailing onshore winds

plentiful supply of sand

presence of obstacles, e.g. vegetation.


Psammosere


Salt marsh ecosystems

The UK has about 45,500 hectares of salt marsh, mostly around parts of sheltered eastern and north-western coasts, often in estuaries or behind spits. The vegetation which develops here changes through time and this succession is called a halosere. They display a marked zonation.


Halosere


What reasons can you think of?

The importance of salt marshes

Salt marsh ecosystems and mud flats are very important for several different reasons.

breeding sites for many birds

feeding ground for large flocks of waders, geese and ducks

stopover area for migratory birds

high tide refuge for birds

important nurseries for many fish, molluscs and crustaceans

natural coastal defence.


Can you name the three main types of coral reef?

Coral reef ecosystems

Coral reefs are unique ecosystems built entirely from biological activity. Corals are tiny polyps which exist in large colonies and leave behind a hard rock-like skeleton of calcium carbonate when they die. Living corals on top of this form a coral reef.

Can you describe the global distribution of coral reefs shown on the map?

fringing

barrier

atoll.


Factors affecting coral reef formation


The importance of coral reefs

Coral reefs are extremely important for several reasons. Study the newspaper articles and discuss their relevance.

Why else are coral reefs important?


The evergreen trees that make up these mangrove ‘forests’ are specialised in order to live in this environment.

How have mangroves adapted?

Why do you think mangroves are important?

Mangroves

Mangroves are coastal wetland forests. They are found in the tropics and sub-tropics, often at the seaward end of sediment-loaded freshwater outlets.

salt-tolerant (halophytes)

interlacing stilt/aerial roots trap sediment

strong wood that is resistant to insect attack.


The mangrove forests and plantations in Bangladesh support an estimated half a

million people. How do they do this?

Mangroves in Bangladesh

Bangladesh has the largest area of mangrove forest in the world. The Sundarbans is the most extensive, covering over 6000

km2 at the mouth of the River Ganges.

Due to its extraordinary biodiversity, the Sundarbans was designated a UNESCO biosphere reserve in 2001.


Key questions: Factors threatening

ecosystems

What threatens coastal ecosystems and what are the causes and consequences of these threats?

What threatens sand dunes and salt marshes?

What has happened to the Thames Estuary?

What threatens coral reefs?

What has happened to coastal ecosystems in Bangladesh?


Factors threatening ecosystems


Coastal ecosystems under threat

Coastal ecosystems are important for many reasons. However, they are in danger from various different threats.

What threats do coastal ecosystems face?

sea level rise

coastal erosion

coastal and marine pollution

global warming

fishing, especially overfishing

population pressure – clearance and over-exploitation

tourism.


Threats: farming and fishing


Threats: industry and tourism


Coastal sand dunes are threatened by a variety of different things, mostly as a result of human activity. Threats include:

Threats to sand dunes

excessive trampling: too much pedestrian use can lead to loss of vegetation and increased erosionfour-wheel drive vehicles and motorcycles: these are even more destructive than pedestrians

overgrazing of livestock: this causes loss of vegetation and, as a result, biodiversityafforestation: conifer plantations reduce biodiversity by preventing natural dune communities developing.

What else threatens coastal sand dunes?


Threats to salt marshes


Along the Thames Estuary, two thirds of the salt marsh has been lost to various factors since 1945.

The Thames Estuary

Why has this happened?

summer grazing selectively removes some species

chemical fertilizer run-off alters plant communities

drainage and ploughing for increased arable production

loss of marsh land for landfill from London

recreational use of the estuary demands space, reduces water quality, causes erosion and disturbs wildlife.


Threats to coral reefs


What human threats does Bangladesh face?

Threats in coastal Bangladesh

Pollution: Release of heavy metals from industrial waste. Untreated sewage from 36 million people. Continued, now illegal, use of toxic pesticides from agriculture.

Deforestation: Poverty and population pressure result in 20 km2 of mangrove clearance each year.

Coastal ecosystems in Bangladesh face numerous threats.

Shrimp farming industry: Growing uncontrollably. 80 km2 of mangroves have been completely cleared for shrimp farming.


Key questions: Sustainable management

What conservation and exploitation processes exist?

How have salt marshes been managed sustainably on the Thames Estuary?

What is Integrated Coastal Zone Management and how has it been put into action in Bangladesh?

How has the Soufriere Marine Management Area in St Lucia conserved biodiversity?


Sustainable management


Conservation versus exploitation


It provides natural flooding and erosion

defence and improves the area’s biodiversity.

What are the benefits of this management?

Thames Estuary management

At Abbotts Hall Farm and Tollesbury Wick on the Thames Gateway in Essex, efforts have been made to protect and extend the salt marsh. They are internationally important areas for wildlife and are both protected as a Site of Special Scientific Interest (SSSI). In the UK over 6 km² of farmland has now been converted back into salt marsh.


It acknowledges that the problems of the coast are closely interrelated and that trying to manage each of these separately rarely works.

Integrated coastal zone management

Integrated coastal zone management (ICZM) is a ‘joined up’ and inclusive approach to coastal zone management. It views the coast, its people and its problems as a whole, rather than as separate entities.

The ultimate aim is sustainability in all areas.


ICZM in Bangladesh


Sustainable fishing

Fishing is important in many coastal ecosystems as both the livelihood for a large number of people and a food source for even more. However, it needs to be managed in order to protect the ecosystem and to be sustainable.

How can sustainable fishing be achieved?

quotas and taxes on catchesrestrict access to fisheriesreduce fishing fleet sizesretraining schemes for alternative employmentcommunity management to encourage self-preservation.

What other measures could be employed?


What do you think resource-use conflicts are?

The SMMA

The Soufriere Marine Management Area (SMMA) in St Lucia was established in 1994. Its twin aims were to:

create a map and plan for management of the arearesolve major resource-use conflicts.


Conserving biodiversity

The Soufriere coastal region on the south-west coast is an area of great ecological biodiversity, with well-developed coral reefs and mangrove swamps.

The SMMA area now covers 11 kilometres of coastline and the adjacent marine area. It includes marine reserves, fishing priority areas, multiple use areas, recreational areas and yacht moorings.

By 1990 the St Lucia Biodiversity Action Plan (BAP) acknowledged that the carrying capacity of these sensitive ecosystems had been exceeded.


Summary quiz


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© Boardworks Ltd 2009 1 of 38 Coastal Ecosystems at Risk Coasts