IB Biology Topic B4.1.5 Conditions Required for Coral Reef Formation Revision Notes (SL/HL)

IB Biology Topic B4.1.5 Conditions Required for Coral Reef Formation Revision Notes (SL/HL) | RevisionDojo

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Reef Corals Build Only Where Several Abiotic Conditions Line Up At Once

Reef-building corals are called hermatypic corals, and they lay down hard skeletons of calcium carbonate.
Their polyps live in a mutualism with zooxanthellae, photosynthetic algae that live inside the coral tissue.
1. The algae supply sugars from photosynthesis, and the coral supplies shelter and nutrients in return.
This partnership is why reef corals only build where light, temperature, water clarity, salinity, pH, and oxygen all fall inside a narrow range at the same time.

Analogy

A reef is like a solar-powered building site that only runs when every condition is met at once.

Shallow, Sunlit Water Powers The Algae That Feed The Coral

The zooxanthellae need bright sunlight to photosynthesise.
Without enough light the algae cannot supply energy, so the coral cannot grow or build its skeleton.
Light fades quickly with depth, which limits reefs to shallow water.
1. Reefs usually form in the upper 50 metres of water.
2. Below this depth too little light reaches the algae for useful photosynthesis.

Tip

Reefs need both shallow depth and clear water, because turbidity blocks light even when the water is shallow.

Clear, Low-Sediment Water Lets Light Reach The Reef

Low turbidity keeps water clear so sunlight can reach the zooxanthellae.
Low sedimentation stops particles settling on and smothering the coral.
Coastal development and deforestation raise sediment runoff into reef waters.

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Reef Corals Build Only Where Several Abiotic Conditions Line Up At Once

Reef-building corals are called hermatypic corals, and they lay down hard skeletons of calcium carbonate.
Their polyps live in a mutualism with zooxanthellae, photosynthetic algae that live inside the coral tissue.
1. The algae supply sugars from photosynthesis, and the coral supplies shelter and nutrients in return.
This partnership is why reef corals only build where light, temperature, water clarity, salinity, pH, and oxygen all fall inside a narrow range at the same time.

Analogy

A reef is like a solar-powered building site that only runs when every condition is met at once.

Shallow, Sunlit Water Powers The Algae That Feed The Coral

The zooxanthellae need bright sunlight to photosynthesise.
Without enough light the algae cannot supply energy, so the coral cannot grow or build its skeleton.
Light fades quickly with depth, which limits reefs to shallow water.
1. Reefs usually form in the upper 50 metres of water.
2. Below this depth too little light reaches the algae for useful photosynthesis.

Tip

Reefs need both shallow depth and clear water, because turbidity blocks light even when the water is shallow.

Clear, Low-Sediment Water Lets Light Reach The Reef

Low turbidity keeps water clear so sunlight can reach the zooxanthellae.
Low sedimentation stops particles settling on and smothering the coral.
Coastal development and deforestation raise sediment runoff into reef waters.

Definition

Paywall

(on a website) an arrangement whereby access is restricted to users who have paid to subscribe to the site.

anim nostrud sit dolore minim proident quis fugiat velit et eiusmod nulla quis nulla mollit dolor sunt culpa aliqua

Duis aute irure dolor in reprehenderit

Note

Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam quis nostrud exercitation.

Excepteur sint occaecat cupidatat non proident

Tip

Lorem ipsum dolor sit amet, consectetur adipiscing elit.
Sed do eiusmod tempor incididunt ut labore et dolore magna aliqua.
Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris.
Duis aute irure dolor in reprehenderit in voluptate velit esse cillum.

A - Unity and Diversity9 subtopics

B - Form and Function10 subtopics

C - Interaction and Interdependence9 subtopics

D - Continuity and Change12 subtopics

IB Biology Topic B4.1.5: Conditions Required for Coral Reef Formation Notes

Reef Corals Build Only Where Several Abiotic Conditions Line Up At Once

Shallow, Sunlit Water Powers The Algae That Feed The Coral

Clear, Low-Sediment Water Lets Light Reach The Reef

anim nostrud sit dolore minim proident quis fugiat velit et eiusmod nulla quis nulla mollit dolor sunt culpa aliqua

Duis aute irure dolor in reprehenderit

Excepteur sint occaecat cupidatat non proident

Unlock the rest of this chapter with a free account

Reef Corals Build Only Where Several Abiotic Conditions Line Up At Once

Shallow, Sunlit Water Powers The Algae That Feed The Coral

Clear, Low-Sediment Water Lets Light Reach The Reef

anim nostrud sit dolore minim proident quis fugiat velit et eiusmod nulla quis nulla mollit dolor sunt culpa aliqua

Duis aute irure dolor in reprehenderit

Excepteur sint occaecat cupidatat non proident

Unlock the rest of this chapter with a free account

A - Unity and Diversity9 subtopics

B - Form and Function10 subtopics

C - Interaction and Interdependence9 subtopics

D - Continuity and Change12 subtopics