Coastal habitats Flashcards
6 conditions for coral reefs
shallow water 25m deep low turbidity(clear water) salinity sunlight(for photosynthesis) strong wave action(supplies O2) warm water(23°C - 25°C)
5 threats for coral reefs
high temperature - corals get rid of algae(bleaching) siltation - sediment blocks sunlight acidic pH parrot fish, crown of thorns and sea star oil/fuels
Polyps
millions of them create a coral reef
they are tiny animals that deposit calcium carbonate
have symbiotic relationship with algae
provide shelter, carbon dioxide, nitrogen and phosphorous(compounds needed for photosynthesis)
Algae in coral reefs
Zooxanthellae
they photosynthesise, providing oxygen, glucose and energy(corals use to make proteins, fats, CaCO3 and carbs)
have symbiotic relationship with polyps
Coral reef value
large biodiversity
protect coastline
rich fish stocks
tourism
7 Mangrove values
protect coastline from erosion and flooding large biodiversity- nurseries for fish restores economy traps silt and helps create new land reduces water pollution carbon sink provide timber for fuel
4 conditions for Mangroves
high temperature - grow only 30° latitude of the equator exposure to too much oxygen is harmful high salinity intertidal zone
4 Mangrove threats
overharvesting
fresh water
pollution from river system
coral reef destruction
Mangrove adaptations
halophytic trees
- salt filtering and excretion
snorkel roots to intake oxygen
tangled roots
5 Salt marsh value
collectors of silt and organic matter carbon sink protection against erosion and flooding nursery areas for fish and crustaceans deliver nutrients to coastal waters
Threats to salt marsh
sea level rise human disturbance industrial and agricultural pollution land reclamation for ports coastal squeeze due to anthropological structures sea defences
Formation of salt marsh
mud and silt are deposited along a sheltered part of the coastline
deposition builds up so mud breaks surface to form mudflats
they are colonised by halophytic plants
Pioneer plants of salt marsh
glasswort and cordgrass
halophytic
- have salt-excreting glands instead of photosynthesising stems
Upper lower marsh vegetation
Pioneer species accumulate sediment
Flocculation of meandering creeks help build up the marsh
Sea purslane grows
Upper marsh vegetation
More sediment and decaying vegetation improves the humus content of the muddy soil
vegetation succession occurs
- sea lavender, sea aster and sea couch grass
can tolerate submergence from extreme high tides
Climax salt marsh vegetation
Elderberry
Oak and ash trees
Sand dune formation
-embryo dunes
beach dries out at low tide and sand is blown to the back of the beach
Sand accumulates and embryo dunes are formed
Pioneer species like saltwort, Lyme grass and sea couch grass
- halophytic and xerophytic (arid tolerant because of the lack of moisture)
Yellow dune formation
Pioneer species trap sediment, forming yellow dunes
they are succeeded by less resilient species
- dominantly marram grass
Marram grass adaptations
have large deep-tap roots which spread(rhizomes)
curling leaves
- cope with fast draining sand soil(reduce evaporation)
Grey dune formation
More sediment is trapped and decaying vegetation improves humus content
pH becomes lower due to humic acid and more moisture
colonised by heather, cord grass, marram grass, red fescue and sea spurge
Dune heath
Surface of soil is leached by rainwater and washes out the basic minerals which reduces the pH even more
colonised by gorse, bracken, heather and brambles
Vegetation climax of sand dune
oak, birch, ash and pine trees
9 users of coastal areas
- local residents
- employers
- farmers
- port authorities
- fishermen
- transport companies
- tourists
- developers
conditions for formation of sand dunes
- wide beach and large quantity of sand
- prevailing wind is onshore(from sea to shore)
- suitable location for land to accumulate
conditions of sand dune
- high salinity
- lack of moisture as sand drains quickly
- high wind
- submergence by wind-blown sand
