Lec #5 Coral reefs and wetlands

Question 1

What are coral reefs?

Answer 1

These are biogenic structures built by organisms and the most biodiverse and extensive hosts to life on the planet

Question 2

What other reefs can there be?

Answer 2

Algal reefs, oyster reefs, mussel reefs…..

Question 3

What heat factors need to be present for a reef to form?

Answer 3

Mean coldest winter 18oC

Mean warmest summer 34oC

Question 4

What are coral polyps?

Answer 4

Small Coraline organisms that can extract calcium from the water and grown by accretion

Question 5

what physical forms can polyps be in

Answer 5

straight, round or branching skeletal sturctures

Question 6

What are the requirements from growth (3, excluding temp and salinity)

Answer 6

Firm sea bed
Lack of sedimentation
Adequate supply of sunlight

Question 7

What are the salinity requirements for coral and the ideal conditions

Answer 7

27-38 ppt, ideally though is 34 - 36 ppt

Question 8

What is the average coral growth rate

Answer 8

between 0.4 and 0.7 mm per year, although there are expections

Question 9

Why would corals stop growing upwards

Answer 9

corals would stop when they reach the sea surface and die due to exposure, although the associated organisms can lead to a solid reef structure above the water

Question 10

Explain growth on the seaward size

Answer 10

this is subject to wave action which prevents collaging from silt and maintains oxygen and nutrient supply, although wave action may break corals and mean only short round ones grow

Question 11

Explanation of growth on the sea side

Answer 11

there is a large range of life due to the protection from the sea side of the coral reef, although sediment is washed over the top of the reef

Question 12

What is the impact of predators on coral growth

Answer 12

these limit the growths of corals, some organims can grow to plauge proportions

Question 13

What is the impact of humans on coral growth, both local and global (4)

Answer 13

marine pollution
quarrying of corals
nutrient concentrations causing eutoprhication
bleaching due to higher ocean temps (salinty too)

Question 14

What are the three types of coral reefs

Answer 14

Fringing, barrier and atolls

Question 15

Explanation of a fringing reef

Answer 15

usually border contient and island shore and are built upwards and outwards from the shore, consist of a reef platform, exposed at low tide,

Question 16

Just what is a boat channel

Answer 16

Some reefs have large areas begind them which is shallow depression known as the boat channel, it becomes a lagoon at low tide and consists of coraline sands

Question 17

What are barrier reefs

Answer 17

these are reefs that have indured changes to sea leel rise frm exposure and then regrowth

Question 18

Why might there be gaps in coral reefs such as the GBR

Answer 18

these may account for prehistoric river outflows, the freshwater would killed the coral reef due to low salinity

Question 19

What are atols

Answer 19

these reefs are typicall circular surrouding a lagoon

Question 20

what are the dimesntions of atols

Answer 20

range from 1km to 100km in diameter

average lagoon 30 to 100m deep

Question 21

What ( and explain) the three types of atols

Answer 21

Oceanic - formed around volcanic deposits, as deep at 550m
Shelf atolls - rise from continental shelf wont be deeper than 500m
Ring atolls - surrounding either earlier or relic atolls

Question 22

What is involved in the formation of mudflats

Answer 22

Silts mud and clays, dispersed by the ocean will only settle in low energy deposition zones, with out erosion mudflats will aggrade and turn into salt marshes

Question 23

Where are areas where wave energy is low enough (3)

Answer 23

Along the fringes of estuaries
behind longitudinal bars
embankments or coves

Question 24

What temporary changes can effect mudflats

Answer 24

during storm conditions and high tidal ranges their presence and size may vary

Question 25

Key points about the biology of mudflats

Answer 25

home to a range of invertebrates and microorganisms
key part of marine system food web
have a bio film secreted by benthic organisms that help stablise a sediment

Question 26

Explain the process in simple steps of a mudflat turing into a slat marsh

Answer 26

stable mudflat - aggradation of sediment will raise surface - surface becomes above water at low tide - organisms will become rooted - stablises, other plants build sediment - salt marsh

Question 27

What do plants do in the creation of mudflats

Answer 27

physical stablisation of mudflats
introduction of organic matter
hydronamics of tidal floods

Question 28

where are salt marshes found

Answer 28

in the upper part of the intertidal zone

Question 29

What forms in salt marshes

Answer 29

tidal creeks

Question 30

What are mangrove

Answer 30

these are shurbs and trees that grow in the upper part ofthe intertidal zone, they are great and diverse on tropical coasts, similar habbit to salt marshes

Question 31

what is needed from mangrove formation

Answer 31

muddy substrates and low wave enery

Question 32

What can increase size of mangroves

Answer 32

if there is a small tidal range (macrotidal) they can exsist for ages