Mangroves

Question 1

What is a mangrove and where do they form

Answer 1

Mangroves are woody trees or shrubs. They flourish at the sea/land interface in sheltered tropical coastal and estuarine regions where fine sediment collects.

Question 2

What percentage of tropical coastlines are mangroves found on?

Answer 2

60-75%

Question 3

Mangorve growth is dependent on 6 main factors, what are they

Answer 3

1. Where water is shallow enough. 2. Low energy sediment depositing shorelines. 3. Adequate light. 4. Water temperature >5C. 5. Air temperature typically high. 6. High rainfall

Question 4

Name 4 types of mangrove

Answer 4

Laguncularia racemosa (White mangrove)
Conocarpus erectus (Buttonwood)
Rhizophora mangle (Red mangrove)
Avicennia germinans (Black mangrove)

Question 5

What is the impact of mangroves having a specialized habitat

Answer 5

Associated fauna and flora have low diversity

Question 6

What is the typical simple zonation of a mangrove system from Seaward zone to landward zone

Answer 6

Seaward - Red mangrove; Black Mangrove; White Mangrove; Buttonwood - Landward

Question 7

What is zonation a function of

Answer 7

Tolerance to tidal regime, salinity, anoxic sediments, stability

Question 8

What are mangroves main adaptations

Answer 8

The roots and mechanisms of salt loss - this attributes to zonation patterns

Question 9

What is the mangrove tidal regime and how does it affect associated flora

Answer 9

1. Landward area drys out - desiccation and high salinity. .2. Tidal flushing washes away salt and hydrates sediments. 3. Tidal immersion provides nutrients. 4. Anoxic sediments release sulfides which are removed by the tide.

Question 10

How to mangroves adapt to thick, waterlogged and anoxic sediment

Answer 10

Root structures that exit sediment, (Pneumatophore, prop roots, kneed roots and plank roots), to enable air to be taken up in pores called Lenticles.

Question 11

What are Lenticles

Answer 11

Pores in mangrove roots that allow gas exchagne but not water an solutes, this enables oxygen to be transportes through channels in the Aerenchyma tissues.

Question 12

What kind of roots are lenticles found

Answer 12

Pneumatophores and prop roots

Question 13

How are mangroves adapted to the saline enviromnement

Answer 13

1. Salt secretions- salt transported to leaves in the sap, is concentrated and secreted though salt glands. 2. Root membranes - semi-permeables menrbane excludes most salt ions and limits uptake

Question 14

What two main problems does the presence of salt cause for trees in marine conditions

Answer 14

1. Uptake of salt disrupts cellular mechanisms. 2. Salt water in sediment reduces osmotic difference between the root and sediment making it difficult to take up water.

Question 15

Name a salt secreting mangrove

Answer 15

Avicennia spp.

Question 16

What salt adaptions to non-salt secretors have

Answer 16

An ultrafilrtration system. This is filtration in the root system - Na+/K+ ion pumps (needs energy) in the xylem. Na+ and K+ ion pumps in the leaves. - Salt is stored in ion saturated filter cells sealed with a suberin coating. - These cells are lost when leaves are shed and pushed back down the plant by growth

Question 17

Name two non-salt secreting mangroves

Answer 17

Rhizophora and Bruguiera spp.

Question 18

How do mangroves reproduce

Answer 18

Seeds germinate on the parent plant - embryo grows through the seed coat and the fruit wall. Seed drops out of the fruit so it is ready to grow quickly in an unstable habitat - it is washed away or falls into mud

Question 19

What is Vivipary

Answer 19

Mangroves demonstrate a degree of vivipary - this is the process of giving birth to the live young and is generally associated with animals - in plants in refers to the seeds germinating on the plant instead of falling

Question 20

Name two species that produce viviparous seeds

Answer 20

Rhizophora and Bruguiera spp.

Question 21

What are two initial issues facing newly dispersed mangrove seeds

Answer 21

Competition from parent plant and limitation of light and nutrients

Question 22

What three components of high energy cost mean that mangroves are only found in the tropics

Answer 22

Being a tree, tolerating salt, and coping with water logged soil - the environmental conditions and light limitation in temperate regions would not allow photosynthesis all year round so the tree would not gain enough energy to survive

Question 23

What terrestrial species are abundant in mangrove habitats

Answer 23

Epiphytic species that can avoid sediment and insects.

Question 24

Name general magrove community fauna

Answer 24

Molluscs, crustaceans, (decapods and cirrepedia), Chelicerates, (spiders, mites and horshoe crabs). Fish, mammals and birds

Question 25

What can Rhizophora mangle, (red mangrove) be used for in antropogenic industry

Answer 25

Timber, paper pulp, cattle fodder, tobacco substitute, wine, fishing line, medical purposes.

Question 26

Why is Rhizophora mangle (red mangrove) used widely for anthropogenic industry

Answer 26

It grows v.tall, 20-30m, can be easily cultivated.

Question 27

What is Avicennia germinans (black mangrove), used for in anthropogenic industry

Answer 27

Not for timber; but can be used as soap substitute, bark used in tanning, flowers for local honey indurties, and medical purposes.

Question 28

What are the main characteristics of Rhizophora mangle

Answer 28

Grows 20-30m tall, trunk diamter of 0.5m. Yield 4 MT C/ha/y. Favors temperature of 21.6 to 25.6C and a pH of 6 to 8.5

Question 29

What are the main characteristics of Avicennia germinans

Answer 29

Grows 25m tall, trunk diameter 30cm
Faster growing - 10 to 20 MT C/ha/y
Favors temperature of 25.3-26C

Question 30

Why are roots important to sessile organisms

Answer 30

They produce and extensive hard substratum for attachment in an otherwise restricted area due to the soft sediment

Question 31

What is an adaption of the Mudskipper

Answer 31

Follows the tide by walking from submerged burrows using modified pelvic and pectoral fins and they are very tolerant to desiccation.
Periopthalmus cantonensis can survive 2.5 days out of water