Coral Reefs Flashcards
What is a Coral Reef?
A coral reef is an offshore ridge, mainly of calcium carbonate, formed by the secretions of small marine animals.
How are Coral Reefs formed?
Coral polyps construct the main frame of coral reefs by using dissolved calcium carbonate in seawater to create a protective limestone casing. Polyps live in colonies and over time new polyps grow on top of the existing structure, adding layer after layer of limestone to the colony.
What do Coral Polyps need in order to grow?
Coral Polyps need warm, clean, shallow, well-aerated water with the right amount of salt.
What are some other organisms that live on the reef as well?
Algae, fish, sponges sea eggs and shellfish
A coral reef provides a habitat for beneficial algae. What is beneficial algae?
Beneficial algae supplies carbon and nutrients which help the coral to grow.
What temperature of water does coral need to grow?
The temperature of the water should be between 21 C and 30 C. Tropical climates
What happens when the water is too hot?
If the water is too hot, the coral will expel the beneficial algae that supply carbon and nutrients to the coral. This is called Coral Bleaching.
Why does the exact depth of the coral matter?
Sunlight must be able to penetrate to where the coral is growing. The clarity of the water depends on the depth that the coral is at.
Why does the exact depth of the coral matter?
Sunlight must be able to penetrate to where the coral is growing. The clarity of the water depends on the depth that the coral is at.
What is a fringing reef?
A fringing reef is a type of coral reef that is close to the shore and separated by a small lagoon
What are the three main activities carried out by waves?
Erosion, deposition and transportation
What are the four ways that erosion is carried out?
Hydraulic action, corrasion, attrition and solvent action
What is hydraulic action?
As waves strikes the cliff, the air in the cracks and joints is trapped and compressed, as the water retreats the air will expand. As this is repeated numerous times the cracks and joints get larger and the rock will break apart
What is corrasion?
Corrasion is when the rocks carried by the waves in hurled against the base of a cliff/shore. After a while, the rock/land is worn away
What is attrition?
The process by which rocks strike each other and are broken down. It is an important source of sand formation.
What is solvent action?
This is the chemical reaction between the seawater and calcium carbonate found in limestone or chalk. The calcium carbonate is converted to calcium bicarbonate and is dissolved in the water. The structure of the rock becomes weak and it crumbles.
What are the features of erosion?
- Headlands and bays
- Geo
- Caves, arches, stacks, stumps
- Blow hole
- Wave-cut platform
What is a headland and bay?
Along the coast there are areas where the land has alternate band of hard and soft rock. The hard rock offers greater resistance to erosion and is worn back slower than the hard rock. The projection of resistant rock are called headlands and bays are the inlets formed within the soft rock found between the headlands
What are caves, arches, stacks and stumps?
These develop along the headland. Waves attack lines of weakness in the rocks on both sides of the headland and large crakes are formed. Over a period of time the rock disintegrates, leaving a circular depression in the headland called a cave. When erosion continues, the two caves are join and it is called a arch. When it continues, the roof collapses and it forms a stack. Further erosion of the stack creates a stump
What is a blow hole?
This is a long, narrow vertical shaft through the roof of a cave through which water escapes. Where there are vertical cracks and joints within the rock, the wave will enter and over a period of time, the material dissolves leaving an opening which pierces the roof of the cave.
What is a geo?
If the face of a cave collapses, the blow hole is exposed as a long narrow inlet with steep vertical walls known as a geo
What is a wave cut platform?
This is a sooth platform at the base of a cliff. It is usually exposed at low tide and may be covered with pebbles, sand and other debris. As the waves attack the cliff, undercutting occurs at the base, creating a notch. Eventually, a hanging cliff develops which later collapses due to its weight. Each time a part of the cliff is broken off and retreats towards the land, the wave-cut platform increases in width
Transportation is carried out by a process called?
Longshore drift
What is longshore drift?
Material is transported along the beach by a combination of swash and backwash. The swash brings material onto the shore at an angle while the backwash removes it perpendicular to the shore
