Coral Reefs

Question 1

What kind of waters do coral reefs grow in

Answer 1

Oligotrophic waters

Question 2

What is the Order name for hard corals

Answer 2

Hexacorallia

Question 3

What is the Order name for soft corals

Answer 3

Octocorallia

Question 4

What percentage do coral reefs cover of the global ocean surface and roughly what proportion of known fish species do they host

Answer 4

<0.1% and a quarter of all known fish species

Question 5

What are hermatypic corals

Answer 5

Reef building corals

Question 6

What are ahermatypic corals

Answer 6

Non-reef building corals

Question 7

What phylum do corals belong to?

Answer 7

Cnidaria

Question 8

What three classes do coral belong too

Answer 8

Hydrozoa, Scyphozoa, Anthozoa

Question 9

Where are coral reefs distributed?

Answer 9

Tropical and equatorial between tropics of Capricorn and Cancer, i warm oceanic waters

Question 10

What is optimum coral water temperature

Answer 10

23-25C

Question 11

Why are corals not found on western continental coasts

Answer 11

Coriolis gyre brings cold water into coastal region - East Africa has a fringing reef, West Africa does not

Question 12

Why are they not found on major river outflows?

Answer 12

High turbidity, smothering, cold water and low salinity

Question 13

What is an endosymbiotic relationship

Answer 13

An endosymbiont is any organism that lives within the body or cells of another organism. Usually the relationship is mutualistic and one tends to benefit or need the other.

Question 14

How does is endosymbioisis relevant to corals

Answer 14

Corals are comprised of two partner organisms; an animal (cnidarian) and a unicellular alga (dinoflagellate in the genus Symbiodinium). The outer membane of the Symbiodinium spp. leaks and benefits the coral polyp. The alga is non motile and fragile so depends on the polyp for structural support.

Question 15

Name 12 features of a coral polyp

Answer 15

Basal plate; Coenosarc; Theca; Gastrodermis; Gastrovascular Cavity; Septum; Digestive Filament; Mesoglea; Mouth; Tentacle; Nematocyst; Epidermis

Question 16

What is a nematocyst

Answer 16

A small capsule containing an ejectable thread that causes a sting

Question 17

What is the epidermis

Answer 17

Outermost layers of skin

Question 18

What is the Coenosarc

Answer 18

Common body of the polyp colony

Question 19

What is the Mesoglea

Answer 19

Translucent jelly like substance containing muscle fibers and nerves

Question 20

What is the theca

Answer 20

The walls surrounding the calyx, (calcium carbonate cup that coral sits in)

Question 21

`Explain the calcification process

Answer 21

1. Calcium from sea water in coelenteron moves into Calicoblastis gastrodermis. 2. Active calcium transport into Calicoblastis epidermis. 3. This turns into Ca^2+ and then Calcium Carbonate in the organic membrane. 4. CO2 from metablism in Calicoblastis epidermis moves into Zooanthellae but also turns to bicarbonate and then Calcium carbonate in organic membrane. 5. CACO3 into Carbonic acid and calcium carbonate, then Bicarbonate converted into CO2 and move to Zooanthellae.

Question 22

How do corals reproduce asexually

Answer 22

Fragmentation folloing an event such as a storm; Colony fission; Budding

Question 23

What is colony fission

Answer 23

Colony splits into two or more during early developmental stages.

Question 24

What is Budding

Answer 24

Asexual reproduction - young polyp grows out of an adult - can divide longitudonally - polyp broadens and divides; or Transversely - one forms from mouth region another from base region

Question 25

Explain sexual reproduction of corals

Answer 25

Corals release eggs and sperm and fertilized eggs develop into ciliated larva, which drift and settle.

Question 26

What is the problem with spawning reproduction?

Answer 26

Vulnerable to catastrophic event and can smother corals

Question 27

What are brooders

Answer 27

Eggs fertilized internally and the ciliated larva develops inside the polyp.

Question 28

What are broadcasters

Answer 28

Release eggs and sperm into the water column for fertilization

Question 29

What factors affect the timing of spawing (possible 8)

Answer 29

1. Sea temperature, .2. Lunar cycle. 3. Day length. 4. Irradience. 5. Wind and currents .6. Rainfall. 7. Chemical stimuli. 8. Latitude

Question 30

What is the effect of latitude on breeding

Answer 30

Higher latitudes have shorter breeding seasons

Question 31

What is monopodal growth

Answer 31

Trunk formed by younger polyp growing on top of an older polyp

Question 32

What is sympodal growth

Answer 32

Young polyp grows at the edges of older polyp

Question 33

What is dychotomic growth

Answer 33

Symmetric division of polyps

Question 34

What are the typical zones of reef zonation from the Lagoon to the Deep water

Answer 34

Back reef; Reef flat; Reef crest; Branching coral zone; Mixed Coral zone and Massive coral zone, (within the forereef); Deep forereed and Platycoral zone

Question 35

Put into order these types of coral based on resistance to wave energy from low wave energy to high: Massive, Mushroom, Branching, Pillar, Encrusting, Tabular

Answer 35

Branching- Pillar - Tabular - Massive - Encrusting - Mushroom

Question 36

What is the substratum of the lagoon like

Answer 36

Sandy

Question 37

What sort of flora and fauna can be found in reef lagoons

Answer 37

Seagrasses, eg, Syrungodium spp. Nursery for reef fish. Benthic organisms like echinoderms, holothuroidae (sea cucumbers). Juvinile sharks and rays

Question 38

What is the physical characteristics of the reef back

Answer 38

Limited water movement, turbid water and lower diversity

Question 39

What sort of organisms found at the reef back

Answer 39

Massive corals, eg. Porites spp., Giant Clam, Tridacna spp. And soft corals, (Octocorallaria

Question 40

What is the physical characteristics of the reef flat

Answer 40

Low tide shallow water, possible exposure

Question 41

What is the dominating coral type at the reef flat

Answer 41

Branching coral, eg Acropora spp

Question 42

What organsims other than coral would you expect to find at the reef flat

Answer 42

Fish - Damsel fish, butterfly fish, Surgeon Fish, Parrot Fish. Invertebrates- Bivalves, gastropods, crustaceans, porifera.

Question 43

What are the physical characteristics of the reef crest and reef front

Answer 43

reef crest shallow with high wave action - often no corals as often exposed

Question 44

What is coral distribution like from reef crest to reef front

Answer 44

Reef crest exposed frequently - often no corals. Moving down reef front characterized by faster growing corals and massive and encrusting corals.

Question 45

What corals are adapted to lower light levels

Answer 45

Slow growing flat tabular corals

Question 46

Give a natural threat to coral reef systems

Answer 46

Grazing pressure from urchins and Crown of thorns starfish - Acanthaster planci

Question 47

Give an anthropogenically induces threat to coral reef ecosystems

Answer 47

Coral bleaching - through loss of zooxanthellae - linked to higher water temperature and light damage