Transcript Slide 1

Mangroves
By Dave Cabrera
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Introduction
• Mangroves – Halophytic (salt tolerant) trees that live in
areas predominantly saturated with salt water
• Found along coastlines between 32 degrees N and 38
degrees S.
• 16-24 families and 54-75 species (classification
dependent)
• Highest diversity in Asia
• New world has 12
• US has 4 (species we will discuss)
• 25% of Caribbean coastline
• 75% of continental regions
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Adaptations to Salt Water
• Salt pores – located on
leaves, root and branches.
Excess salt absorbed from
soil secreted
• Salt exclusion – roots of
some mangroves exclude salt
• Viviparity – seeds germinate
while attached. Fully
developed seedlings drop
from tree.
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Adaptations to Low Oxygen in Soil
• Prop Roots – roots
exposed to air (red
mangroves)
• Pneumatophors – pencillike roots that stick up from
the substrate (black
mangroves)
• Lenticels – slits in the bark
and roots
• Aerenchyma – air spaces
that allow gas to reach
underground roots
Prop roots
Pneumatophors
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Lenticels
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Role of Mangrove Ecosystem
• Mangroves as a Buffer
– Protects coastline from wave action
– Prevent erosion, and keep sediments from
reaching coral reefs
– Collect and stabilize sediments
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Role of Mangrove Ecosystem
• It has been highly debated as to whether succession
occurs in mangroves. The evidence is inconclusive as to
whether this happens and is considered hypothetical.
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Role of the Mangrove Ecosystem
• Mangroves as a nursery
and a habitat
– Detritus from leaves –
Bacteria feed off detritus
– Bacteria – provide food for
planktonic organisms
– Plankton – Serve as food
for larval and juvenile fish
and invertebrates
– Shelter – protection from
predators
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Roll of mangrove ecosystem
• Diversity of species in mangroves
– Trees – 54-75 species in 16-24 families
– Poriferans – sponges grow on prop roots
– Annelids – segmented worms live in mud and
among prop roots
– Cnidarians – anemones occupy prop roots
– Molluscs – Gastropods (periwinkles) and bivalve
(oysters) found on prop roots
– Echinoderms – Sea cucumbers, sea stars
– Urochordates – tunicates attach to roots
– Birds – use tree tops
– Fish – swim among roots
– To name a few
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Species of Mangroves
• Red Mangrove (Rhizophora
mangle)
– Location – found nearest to
water
– Leaves elliptical and leathery.
Dark green on top, pale green
underneath
– Prop roots – large aerial roots
extend from tree into ground
– Roots submerged
– Tolerant of low oxygen
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Red Mangrove Dispersal
• Seedling dropped from tree
• Floats root down in water
• When it comes in contact with
substrate it takes root and
grows
• Can float around for over a
year
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Red Mangrove Dispersal
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Species of Mangroves
• Black Mangrove (Avicennia
germinans)
– Location – Shoreward of red
mangroves
– Leaves – Oblong. Dark green on
top, pale grey to white underneath.
Often encrusted with salt.
– Pneumatophores – Pencil-like root
extensions that provide surface
area for gas exchange
– Roots submerged only at high tide
– Tolerant of low oxygen
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Species of Mangroves
• White Mangrove
(laguncularia racemosa)
– Location – Terrestrial side of
mangrove stands. Behind black
mangroves.
– Leaves – Broad flattened and
oval. Leaves branch out from
stem opposite to each other
– Salt Pores – Present at base of
leaves
– Soil fully saturated with water
– Tolerant of salty soils
– Less tolerant of high water
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Species of Mangroves
• Buttonwood (Conocarpus
erectus)
– Location – Terrestrial side of
mangrove stands, behind black
mangroves. Not a true mangrove
– Leaves – Elliptical and leathery.
Dark green on top, pale green
underneath
– Salt Pores – Present at base of
leaves
– Soil is damp, but not saturated
– Tolerant of salty soils
– Not tolerant of high water
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Threats to Mangrove Ecosystem
• Deforestation
– Coastal development
– Shrimp farming
– Flooding
– Charcoal and timber industry
Rice
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Shrimp and development
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Threats to Mangrove Ecosystem
• Pollution
– Point source pollution – sewers, industrial
discharge, oil spills
– Non-point source pollution – agriculture runoff
Oil
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