Coasts KQ2 (Mangroves) Flashcards
What are mangrove ecosystems?
- Most productive and biologically complex ecosystems
- Salt tolerant plants grown in tidal mud, waterlogged soils on sheltered coasts
- Adapted to harsh coastal conditions
(Strong winds and waves, poor oxygen content, sediment and silt from rivers, inundation by saltwater twice a day)
Environmental conditions affecting mangrove growth
1) Saline
2) Low lying coasts + Low wave energy to encourage deposition
3) Sheltered coasts w/ muddy and waterlogged land
4) High temperatures >27*
5) High rainfall
Adaptations of mangroves
- Roots
- Fruits
- Leaves
- Horizontal zoning
Root adaptations
1) Aerial roots (i.e. Avicenna, Sonneratia)
- Takes O2 directly from atmosphere
2) Prop Roots (i.e. Rhizophora)
- Anchors trees
- Prevents uprooting or toppling
- Takes O2 from above tides
3) Kneed roots (i.e. Bruguiera)
- Traps soil between roots for nutrients
- Essential for plant growth
Fruit adaptation
1) Javalin shaped
- Pierce soft muddy ground
- Germinate immediately after being propagated
2) Buoyant
- Floats away and germinates at other coastal areas
Leaf adaptation
1) Evergreen, thick and leathery
- Reduces excess transpiration, reduces evap. resulting in increased salt concentration in soil
2) Drip tips
- Prevents accumulation of water on leaves
- Water causes rotting and burning
3) Salt excreting glands
- On underside of leaf to allow salt to fall via wind and gravity
Horizontal zoning adaptation
1) Coastal zone
- Frequently flooded by salt water
- Salt water mangroves found
- Aerial roots to anchor deeply, breathe during low tide
2) Middle zone
- Mud is deep and rich in organic matter
- Prop roots help elevate plant above water
- Upper roots help respire
- Lower, buried roots absorb nutrients and stabilise tree
3) Inland zone
- Infrequently flooded
- Freshwater mangroves found
- Kneed roots trap soil and provides stability
- Protrusions take in O2 from atmosphere
Value of Mangroves
1) Stabilise shorelines
2) Protect coasts from erosion
3) Breeding grounds
4) Filters water
5) Economic and social value
How do mangroves stabilise the shoreline?
- Dense network of roots absorb wave energy
- Roots trap sediments, extend coasts, slows erosion
How do mangroves slow coastal erosion?
- Roots slow and absorb wave energy
- Sediment accumulated increases friction between seabed and waves, slowing approaching waves, reducing erosion
- Mangrove forests provide buffer between open coast and land, prevents damage to infra.
How do mangroves provide breeding grounds?
- Provide anchor for marine creatures
- Provide food for marine creatures
- Provide suitable habitat/safe haven for breeding
How do mangroves filter the water?
- Rhizofiltration absorbs pollutants
- Roots and trapped sediments act as filters
- Traps heavy metals and impurities
How do mangroves benefit locals economically and socially?
1) Economic activities
- Wood/non-wood products (i.e. timber, medicine)
- Construction materials
- Food/Agriculture grounds
2) Cultural
- Home to indigenous residents
- Provide food, medicine etc
- Important for traditional cultures
3) Social
- Opportunity for education and scientific research
- Opportunity for ecotourism
Pressures on mangroves
Natural:
1) Climate change
Human:
1) Clearing of mangroves
2) Conversions to other land use
3) Coastal developments
Natural Pressures on mangroves: Climate change
> Rising sea levels
- Mangroves unable to colonise as coastal areas decrease
- Compete with humans for land
e.g. Thailand
