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GEOL200 > Week 12: Coral reefs > Flashcards

Week 12: Coral reefs Flashcards

1
Q

Coral reef community

A

Most diverse ecosystem on planet

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2
Q

What is a coral reef?

A

Consist of a living framework w internal cavities filled w sediment and a surrounding area of reef-derived skeletal grains
High energy environment- 1st to obtain nutrients
*Abiotic structure created by biotic means

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3
Q

Three main types of coral reefs

A
  1. Fringing reefs
  2. Barrier reefs
  3. Atolls
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4
Q

Fringing reefs

A

Non existent or shallow back reef zone, may connect directly to land
Located nearshore
Most common
ex.Ningaloo reef in west australia

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5
Q

Barrier reefs

A

Separated from land by a deep channel or lagoon
Outer edge is raised for food supply and to grow quickly
ex.great barrier reef

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6
Q

Atolls

A

Ring shaped island of coral reefs and coral debris
Encloses a shallow lagoon

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7
Q

Darwin and reef development

A

Believed it was a consistent pattern from fringing to barrier to atoll
BUT WRONG
Didnt account for sea level rise

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8
Q

Who builds the reef (part 1)?

A

Phylum Cnidaria - corals, sea anemones and jellies
All have specialized cells (cnidocytes) for protection and capturing prey

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9
Q

2 basic body forms of cnidaria

A
  1. Free swimming/floating medusa ex. jellies
  2. Sessile polyps ex. corals
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10
Q

How do cnidaria sting?

A

Their cnidocytes (stinging cells) contain nematocysts

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11
Q

How do cnidaria reproduce?

A

Sexually and asexually

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12
Q

Who builds the reef (part 2)?

A

Hermatypic corals contain tiny plant like organisms living in their tissue (zooxanthellae)

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13
Q

Zooxanthellae

A

Tiny photosynthetic algae living in tissue of most corals
Mutualism- coral supply nutrients, zooxanthellae supply food

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14
Q

Who builds the reef (part 3)?

A

Scleractinla (order)- stony or hard corals
Create a hard calcareous skeleton
Secrete aragonite

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15
Q

Who builds the reef (part 4)?

A

Coral polyp (stomach, tentacles and mouth)
Secretes CaCO3 to build hard outer skeleton

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16
Q

What type of organism are reef corals?

A

Mixotrophs

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17
Q

Energy needs of coral

A

10% from food capture
90% from zooxanthellae

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18
Q

What type of water is coral most efficient in?

A

Oligotrophic environments (nutrient poor)
Ensures adequate sunlight bc it isnt blocked

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19
Q

Ideal conditions for reef growth

A

Clear(nutrient poor), brightly lit, warm, shallow water, normal-slightly elevated salinity, strong wave activity to bring nutrients in

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20
Q

Ideal temp for coral growth

A

25-29 degrees celsius

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21
Q

Ideal salinity for coral growth

A

25-35 %

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22
Q

What happens if there is drastic change in conditions for coral?

A

Zooxanthellae leave and it causes a coral bleaching event

23
Q

Horizontal zonation of coral reefs

A

Reef front (reef slope)
Reef crest
Reef flat
Back reef (lagoon)

24
Q

Vertical zonation of coral reef

A

Deeper= less light , less wave energy, reduced diversity

25
Q

Delicate, branching corals

A

Low wave energy, high sedimentationT

26
Q

Thin, delicate, plate like

A

Low wave energy, low sedimentation

27
Q

Globular, bulbous, columnar

A

Moderate wave energy, high sedimentation

28
Q

Robust, dendroid, branching corals

A

Mod-high wave activity, moderate sedimentation

29
Q

Hemispherical, irregular, massive corals

A

Mod-high wave activity, low sedimentation

30
Q

Encrusting corals

A

Very high wave activity, low sedimentation

31
Q

Tabular corals

A

Moderate wave activity, low sedimentation

32
Q

Reef crest

A

Highest part of reef, exposed at low tide
Greatest wave action
Buttress zone

33
Q

Reef flat

A

Calm shallow water
Tolerate a wide range of temp, light intensity and salinity
Adapt to low O2 levels
ex. heron island

34
Q

Gorgonian corals (soft corals)

A

Found in reef flat
Dont produce hard CaCO3 structure
“Sea whips”

35
Q

Sea cucumbers

A

Echinodermata- sea stars and urchins
Marine, benthic, found at all depths (reef flat)
Scavengers and deposit feeders

36
Q

Deposit feeding

A

Ingest sediment and extract organic matter from itg
Poop out biogenous sediment

37
Q

Types of organisms in the reef ecosystem

A
  1. Builders
  2. Dwellers
  3. Grazers
  4. Destroyers
38
Q

Builders

A

Corals
Calcareous red algae

39
Q

Dwellers

A

Bivalves
Calcareous green algae
Fish
Sponges
Anemones
Tunicates
Crabs

40
Q

Grazers

A

Echinoderms
Gastropods
Some fish

41
Q

Destroyers

A

Sponges
Bivalves
Annelids

42
Q

Sponges

A

Sessile
Benthic filter feeders
Symbiotic relationship w algae

43
Q

Calcareous algae

A

Imp component of reefs
Articulated- attached to substrate by calcified holdfasts
Non-articulated- crusts/encrusting

44
Q

Three main classes of molluscs

A

All share a common ancestor
1. Cephalopoda (squid, octopuses)
2. Bivalvia (scallops, mussels, clams, oysters)
3. Gastropoda (snails, slugs, sea slugs)

45
Q

Components of molluscs

A

Food for movement
Mantle: creates shell
Shell: protects visceral mass
Radula: tiny teeth (scraper to scrape coral)

46
Q

Mobile invertebrates

A

Snails, limpets, abalone
80% of mollusc species

47
Q

Filter (suspension) feeding

A

Cant move, attached to substrate (clams, oysters, molluscs)
Water passes through, filters food particles out

48
Q

Parrot fish

A

Bioerosion
Try to break coral down using teeth

49
Q

Giant clams (tridacna) - molluscs

A

Siphon- water flow , used for locomotion, feeding, respiration, reproduction
Symbiotic algae in mantle

50
Q

How do corals provide coastal protection?

A

reduce shoreline erosion by absorbing energy from waves, protect coastal housing, agricultural land and beaches

51
Q

Threats of coral bleaching

A

Climate change-water temp
Low tides- exposure
Overexposure to sunlight
Pollution

52
Q

Ocean acidification threats to coral reef community

A

Harder for corals to create aragonite
Corals have to expend more energy to build skeletons
Slows rate at which coral reefs generate CaCO3 and build skeleton
Try to take shortcuts making their structures weaker

53
Q

Threats to the coral reef community

A

Coral bleaching
Ocean acidification
Plastic pollution
Crown of thorns sea star

GEOL200 (10 decks)

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