Mangroves Flashcards
What is a mangrove and where do they form
Mangroves are woody trees or shrubs. They flourish at the sea/land interface in sheltered tropical coastal and estuarine regions where fine sediment collects.
What percentage of tropical coastlines are mangroves found on?
60-75%
Mangorve growth is dependent on 6 main factors, what are they
- 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
Name 4 types of mangrove
Laguncularia racemosa (White mangrove) Conocarpus erectus (Buttonwood) Rhizophora mangle (Red mangrove) Avicennia germinans (Black mangrove)
What is the impact of mangroves having a specialized habitat
Associated fauna and flora have low diversity
What is the typical simple zonation of a mangrove system from Seaward zone to landward zone
Seaward - Red mangrove; Black Mangrove; White Mangrove; Buttonwood - Landward
What is zonation a function of
Tolerance to tidal regime, salinity, anoxic sediments, stability
What are mangroves main adaptations
The roots and mechanisms of salt loss - this attributes to zonation patterns
What is the mangrove tidal regime and how does it affect associated flora
- 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.
How to mangroves adapt to thick, waterlogged and anoxic sediment
Root structures that exit sediment, (Pneumatophore, prop roots, kneed roots and plank roots), to enable air to be taken up in pores called Lenticles.
What are Lenticles
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.
What kind of roots are lenticles found
Pneumatophores and prop roots
How are mangroves adapted to the saline enviromnement
- 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
What two main problems does the presence of salt cause for trees in marine conditions
- 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.
Name a salt secreting mangrove
Avicennia spp.
What salt adaptions to non-salt secretors have
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
Name two non-salt secreting mangroves
Rhizophora and Bruguiera spp.
How do mangroves reproduce
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
What is Vivipary
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
Name two species that produce viviparous seeds
Rhizophora and Bruguiera spp.
What are two initial issues facing newly dispersed mangrove seeds
Competition from parent plant and limitation of light and nutrients
What three components of high energy cost mean that mangroves are only found in the tropics
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
What terrestrial species are abundant in mangrove habitats
Epiphytic species that can avoid sediment and insects.
Name general magrove community fauna
Molluscs, crustaceans, (decapods and cirrepedia), Chelicerates, (spiders, mites and horshoe crabs). Fish, mammals and birds
What can Rhizophora mangle, (red mangrove) be used for in antropogenic industry
Timber, paper pulp, cattle fodder, tobacco substitute, wine, fishing line, medical purposes.
Why is Rhizophora mangle (red mangrove) used widely for anthropogenic industry
It grows v.tall, 20-30m, can be easily cultivated.
What is Avicennia germinans (black mangrove), used for in anthropogenic industry
Not for timber; but can be used as soap substitute, bark used in tanning, flowers for local honey indurties, and medical purposes.
What are the main characteristics of Rhizophora mangle
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
What are the main characteristics of Avicennia germinans
Grows 25m tall, trunk diameter 30cm
Faster growing - 10 to 20 MT C/ha/y
Favors temperature of 25.3-26C
Why are roots important to sessile organisms
They produce and extensive hard substratum for attachment in an otherwise restricted area due to the soft sediment
What is an adaption of the Mudskipper
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
