Tropical Communities

Question 1

what is the global distribution of coral reefs?

Answer 1

tropical
- tropics of cancer and capricorn (broadly)
BUT @ higher latitudes

Question 2

why reefs not found between the tropics in certain locations?
e.g./hint South America

Answer 2

water currents
deep ocean upwelling - cold water
cold water surface currents

TOO COLD FOR REEF BUILDING CORALS

Question 3

what are coral reefs composed of?

Answer 3

CaCO3

skeletons of colonial polyps

Question 4

what are polyps?

Answer 4

anemone-like organisms with a CaCO3 skeleton

Question 5

what are responsible for most of the CaCO3 secretion in coral reefs?

Answer 5

stony corals
Phylum: Cnidaria
order: Scleractinia
a few mm wide

Question 6

what does ‘Hermatypic’ mean?

Answer 6

reef-building (corals)

Question 7

what are hexa-corals?

Answer 7

have 6-sided radial symmetry

Question 8

what are octa-corals?

Answer 8

have 8-sided radial symmetry

Question 9

what is an example of hexa-corals?

Answer 9

stony corals

Question 10

what is the organism with which reef-building corals form a symbiosis?

Answer 10

symbiotic zooxanthellae

Question 11

Example of a species of coral which undergoes sexual reproduction: spawning

Answer 11

Montastrea cavernosa

Question 12

what is the typical lifecycle of coral?

Answer 12

1. eggs in water
2. planula larva
3. settles down on seabed (after couple of days) and develops into polyp

Question 13

what is a common genus of branching coral

Answer 13

acropora

Question 14

colony growth forms

Answer 14

branching 
massive
foliaceous 
pillar 
solitary 
plate 
encrusting

Question 15

main framework coral of reef in Pacfic and Indian Ocean

Answer 15

Family: Poritidae = main mass of reef

HUGE

Question 16

main framework coral of reef in western Atlantic Ocean (e.g. Caribbean)

Answer 16

Family: Faviidae

Question 17

what are hydrozoa?

Answer 17

another group of cnidarians (reef-building coral also in.)

Question 18

which family of hydrozoa are CaCO3 secreting?

Answer 18

millepridae

Question 19

what are ‘soft’ corals?

Answer 19

no external CaCo3 skeleton

- may have CaCO3 spicules

Question 20

different species which make up reefs

Answer 20

branching coral 
plate/encrusting coral 
fire corals 
soft corals 
sponges 
giant clams 
fishes 
invertebrates

Question 21

types of reef

Answer 21

fringing reef
barrier reef
atolls
patch reefs

Question 22

what are fringing reefs?

Answer 22

• grow almost up to shore line

- some secrete mucus to survive exposure periods

Question 23

what are barrier reefs?

Answer 23

futher away from shore

- land between shore and reef has subsided due to tetonic activity leaving gap of deeper water

Question 24

what are atoll reefs?

Answer 24

circular formations surrounded by very deep water

- old extinct volcano island sinks and collapses into see leaving rim

Question 25

what are patch reefs?

Answer 25

small structures, found within lagoons

Question 26

why are coral reefs more productive than tropical rain-forests?

Answer 26

warmer conditions, nutrients recycled wells, good at catching nutrients that goes by

Question 27

case study of coral reef-algae phase shift

Answer 27

Hurricane Allan - Caribbean | - rainfall reduced water salinity

Question 28

what is thermal stress?

Answer 28

when temperatures rise 1 degree Celsius above highest temperature expected that year

Question 29

where are mangroves found?

Answer 29

sub-tropical and tropical (tropics of cancer and capricorn) sheltered shorelines

Question 30

mangrove tree adaptations

Answer 30

1. erenchyma 2. don't tend to have a deep tap root 3. buttress roots (prop) 4. salt elimination 5. propagule and seedlings

Question 31

what salt elimination adaptations can mangrove trees have?

Answer 31

1. secrete salt from underside of leaves 2. nectaries - glands which secrete salt 3. salt washed from leaves

Question 32

what are erenchyma?

Answer 32

soft and spongy tissue - allows aeration (O2 to roots)

Question 33

Mangrove habitat organisms

Answer 33

1. mud lobster 2. crabs 3. molluscs 4. termites 5. fish 6. reptiles 7. birds 8. mammals 9. seagrass

Question 34

what are the different roles of crabs in mangrove environments?

Answer 34

feed on algae and detritus on mangrove roots | some shred dead leaves - adding to sediment

Question 35

what propagule and seedling adaptations do mangrove trees have?

Answer 35

continue to develop as travel in water | at point in development when settle bottom become heavy and as tide goes out, digs into sediment

Question 36

what are the two forms coral can take?

Answer 36

polyp cups or corallites in massive skeleton

Question 37

which type of zooxanthellae are found in coral-algae symbiosis?

Answer 37

dinoflagellates

Question 38

where are the symbiotic zooxanthellae found in the coral?

Answer 38

in cells in the gastrodermal layer

Question 39

what is a conspicuous member of Atlantic coral reefs?

Answer 39

Fire Coral | - strong piercing (painful) nematocysts

Question 40

what are some key reef echinoderms?

Answer 40

sea urchins and starfish

Question 41

example of exploitative competition between corals

Answer 41

branching coral grows faster than encrusting or massive coral - branching coral extends self over encrusting and massive coral, shading them out

Question 42

example of interference competition between corals

Answer 42

some slow-growing coral species can extend filaments from gastrovascular cavities that, when encounter living tissue from another colony (of a different species), digest the tissue (kill)

Question 43

what are cryptofauna on coral reefs

Answer 43

sponges/bryozoans/tunicates - small colonial (non-coral/algae) encrusting invertebrates

Question 44

role of damselfishes in coral reefs

Answer 44

have algae gardens - no coral can survive there

Question 45

role of encrusting red coralline algae in coral reefs

Answer 45

maintain integrity of coral reef, cement various pieces together with CaCO3

Question 46

role of green coralline algae in coral reefs

Answer 46

significant contributors to sand

Question 47

other roles of algae on coral reefs

Answer 47

some bore into coral skeletons - reef break down create shade food

Question 48

what are the four models of fish species diversity and community structure in coral reefs?

Answer 48

competition model lottery hypothesis predation-disturbance model recruitment limitation

Question 49

what is the coral reef fish species diversity and community structure problem?

Answer 49

not enough diversity in habitats to explain high diversity of reef fish

Question 50

what are the two factors that the coral reef fish species diversity and community structure models consider?

Answer 50

importance of recruitment processes VS importance of postrecruitment competition

Question 51

what mangrove grows at water's edge?

Answer 51

red mangrove

Question 52

what are mangroves?

Answer 52

salt-tolerant trees and shrubs | a group of different taxa of trees - not an official groups itself

Question 53

where are mangroves found?

Answer 53

between the mean tidal level and extreme higher water of spring tides

Question 54

where to mangroves grow?

Answer 54

waterlogged soil saline environments muddy sediments

Question 55

what is the soil of mangroves like?

Answer 55

anaerobic (bacteria)

Question 56

what are hard bottom mangroves?

Answer 56

live in shallow sediment | - overlies reef/rocky areas

Question 57

which habitats can magroves be found in?

Answer 57

deltas, estuaries, rivers, sheltered bays, lagoons, lee shores of islands (sheltered locations)

Question 58

why can't mangroves tolerate wave action?

Answer 58

would strip away soil from around roots

Question 59

magroves are a ______ systesm

Answer 59

detritus

Question 60

seagrasses are...

Answer 60

submerged angiosperms