Class 10 - mangroves and coral reefs Flashcards
Are mangrove ecosystems mixed?
Very mixed ecosystems because of tides, one hour for birds and insects, the next for fish and prawns, and freshwater fish mingle with saltwater fish
Define mangroves
Trees or large shrubs including ferns and palms that normally grow in or adjacent to the intertidal zone and have adapted special adaptations to survive
How many mangrove species are there?
73 species in total, 38 core species
What characterises the soil?
Soil characterised by regular inundation, variable salinity, from deep peats to shallow sand
How do mangroves exclude salt to survive?
Using filtration at the roots – some deposit it on bark, dump it in their leaves, actively secrete salt from the leaves
Characterise each type of mangrove root
Stilt roots (looping, branch like, travels some distance away from the water), Pneumatophores (upwards extensions into the air above the water), knee roots (rounded, knob-like, extending up into the air), buttress roots (extension of the trunk, plank like form extending above the soil)
What do all roots have?
All roots have abundant lenticels or pores to enable gas exchange – when submerged they close and oxygen is used by the plant and CO2 is absorbed into the seawater
How do mangroves reproduce?
All use water and tides to disperse offspring and some have developed vivipary where trees release growing plants rather than seeds or fruits. Most seedlings settle close to their parents
Can mangroves survive intense salinity?
Some species can survive semi-permanent inundation or periods where salinity is greater than seawater and others cannot survive any salinity equal to pure seawater
Where do mangroves thrive?
Mangroves thrive where seawater is diluted by high rainfall, groundwater flows or rivers
How tall can mangroves be if conditions are good?
30 meters or more
Where are mangroves found?
Mangroves are found in river deltas, estuaries (the sea has flooded a former river valley), coastal lagoons, along open coastlines
Are mangroves ever found without a connection to the sea + example?
Some mangroves are found inland without any connection to the sea – on Christmas island a small forest like this may have survived since growing at sea level 120,000 years ago
Define the three types of mangrove formations
Fringing (narrow strips tracing a shoreline, lagoon or channel), basin (broader formations away from water’s edge), overwash (patches, islands of mangroves entirely covered by waters at high tides)
How much area is covered by mangroves?
Total area of mangroves: 150,000 km2 = conciderable decline because of humans – less than 1% of TF
What happened around Java?
Around Java, losses are so extensive that there is almost no indication that there were once mangroves
In how many countries are mangroves found?
Mangroves are found in 123 countries, over 2/3 in just 12 countries, Indonesia number 1 with 20% of all
What species extends from SA to the red sea and across the pacific islands?
Avicennia marina
What species extends all of West Africa, South America, Mexico and Florida?
Rhizophona mangle
Define the two realms of mangroves?
IWP (Eastern) and AEP (western) – almost no overlapping species with only one fern in common
How many species do the two realms have?
The IWP has 62 unique species and the AEP only has 12 – but they cover almost half of global mangrove area each
Do mangroves have one evolutionary origin?
Mangroves may have developed independently as many as 15 times
When did mangroves first occur?
60 million years ago