#28 coral reefs and temperate zones

Question 1

what is a coral reef

Answer 1

a living system made of calcium carbonate built by corals and algae

Question 2

what do corals require to survive

Answer 2

they have symbionts called zooxanthellae (a dinoflagellate) that live in them. they are photosynthetic and convert sun into sugar for the coral. without them the coral will die

Question 3

what are the types of reefs

how are they made

Answer 3

fringing reef, barrier, reef, atoll, patch reef

reefs are made by volcanic activity that make an island. microbes will settle on this

Question 4

what physical factors do coral need to grow?

Answer 4

temp., low nutrients, light, sea level
coral have an optimum temperature of 23-25 degrees - if its too hot the zooxanthellae will eject and the coral will die - coral bleaching
corals like low nutrient environments - if there is too much nutrient the algae will take over and cause an algal bloom

Question 5

what is the holobiont

Answer 5

the bacteria, symbionts and coral colony as one big biological unit
bacteria is important for coral health - they recycle nutrients for the coral

Question 6

what are different coral morphologies and their characteristics

Answer 6

massive, branching or encrusting

massive: slow growing, large, dome shaped
branching: fast growing
encrusting: lichen-like, low spreading

Question 7

what are the ways coral can reproduce

Answer 7

many ways:
asexual 
sexual 
fragmentation 
broadcast spawning

Question 8

what is in the coral reef community

Answer 8

macro-algae - competing with coral
algae
sponges - nutrient recyclers, filter water
molluscs - can have symbiosis with coral
crustaceans
echinoderms - urchins can eat algae and keep it under control
fishes

Question 9

who does coral compete with?

Answer 9

coral competes with algae
but it also competes with other coral - coral will put digestive enzymes on its neighbour to try make more room for itself

Question 10

what are symbiosis in corals?

Answer 10

mutualism: zooxanthellae and coral, guard crab and coral
commensalism: coral and shrimp - shrimp benefits
parasitism: parasitic nudibranchs

Question 11

what are sea mounts

Answer 11

they are hot spots for production, there is more light penetration, more photosynthesis and hence more fish here - some are in the temperate zone

Question 12

what is special about temperate marine fauna

why

Answer 12

80% is endemic

because they have been isolated for millions of years, the currents act as barriers hence the endenism

Question 13

is temperate or tropical reefs more diverse?

Answer 13

tropical

Question 14

what are the marine habitats in the temperate zone?

Answer 14

intertidal rocky shores
sub-tidal rocky reefs
seagrass beds
kelp forests
Bonney upwelling

Question 15

what are the characteristics of the rocky shore

Answer 15

temperate zone
zonation - strong biophysical gradients driven by the tide
consists of:
- the littoral zone
always exposed to the sun, lots of splashing of water
lichens, barnacles, limpets, molluscs live here because they have adaptations to survive these areas such as shell for low tides and a radula to eat prey/algae

• the intertidal zone
  sometimes covered by water, sometimes exposed to sun
• the sub-tidal zone
  always covered in water, never fully exposed
  temperate rocky reefs are more productive than tropical ones but not as diverse. dominated by algae and provide complex habitat for many endemic species

Question 16

what occurs when you get closer to the shore from a temperate rocky reef?
what happens when you get further away?

Answer 16

• when you get closer to the shore the risk of dessication, salinity and temperature increases
• when you get further away the risk of predation, competition increases and big waves

Question 17

what are seagrass beds for?

Answer 17

they are nursery grounds for fish
they provide food and shelter
important for nutrient recycling

Question 18

what are kelp forests made of and where are they

Answer 18

brown seaweed

occur in Tasmania only

Question 19

what is a bonney upwelling where is it

Answer 19

occurs of the coast of SA
lots of productivity 
deep flinders current is cold and creates and upwelling when the leeuwin current is weak
brings nutrients up 
attracts large animals like whales

Question 20

what is the topicalisation of temperate waters?

Answer 20

from climate change effects
warm marine currents are starting to move south
warmer patches of water are coming south
more species are starting to move south

Question 21

what are indirect and direct effects of temperature on species range?

Answer 21

direct effects: species may only be able to deal with certain physiological factors i.e. may only be able to tolerate a certain amount of O2 in the water

indirect effects: changes in the food web, introduced predators, competition to an area

Question 22

why are temperate marine species most at risk from climate change?

Answer 22

temperate species can only move south so far - they are running out of space to move