#28 coral reefs and temperate zones Flashcards
what is a coral reef
a living system made of calcium carbonate built by corals and algae
what do corals require to survive
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
what are the types of reefs
how are they made
fringing reef, barrier, reef, atoll, patch reef
reefs are made by volcanic activity that make an island. microbes will settle on this
what physical factors do coral need to grow?
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
what is the holobiont
the bacteria, symbionts and coral colony as one big biological unit
bacteria is important for coral health - they recycle nutrients for the coral
what are different coral morphologies and their characteristics
massive, branching or encrusting
massive: slow growing, large, dome shaped
branching: fast growing
encrusting: lichen-like, low spreading
what are the ways coral can reproduce
many ways: asexual sexual fragmentation broadcast spawning
what is in the coral reef community
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
who does coral compete with?
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
what are symbiosis in corals?
mutualism: zooxanthellae and coral, guard crab and coral
commensalism: coral and shrimp - shrimp benefits
parasitism: parasitic nudibranchs
what are sea mounts
they are hot spots for production, there is more light penetration, more photosynthesis and hence more fish here - some are in the temperate zone
what is special about temperate marine fauna
why
80% is endemic
because they have been isolated for millions of years, the currents act as barriers hence the endenism
is temperate or tropical reefs more diverse?
tropical
what are the marine habitats in the temperate zone?
intertidal rocky shores sub-tidal rocky reefs seagrass beds kelp forests Bonney upwelling
what are the characteristics of the rocky shore
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
what occurs when you get closer to the shore from a temperate rocky reef?
what happens when you get further away?
- 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
what are seagrass beds for?
they are nursery grounds for fish
they provide food and shelter
important for nutrient recycling
what are kelp forests made of and where are they
brown seaweed
occur in Tasmania only
what is a bonney upwelling where is it
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
what is the topicalisation of temperate waters?
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
what are indirect and direct effects of temperature on species range?
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
why are temperate marine species most at risk from climate change?
temperate species can only move south so far - they are running out of space to move
