Mangroves

• salt-tolerant, woody trees – really land plants• flowering plants - with true roots, stems, and leaves

• warm, tropical and sub-tropical regions

• cover 60 – 75% of tropical shores

• found in protected, coastal areas

• intertidal

• where salt marshes would be in temperate zone

• salty, muddy water

• anaerobic sediments

Functions:• protect coastal lands from

storms and erosion• filter runoff• accrete sediments

• gradually extend land seaward – eventually replaced by land plants = ecological succession

Functions:

Habitat Value:• very important for

other organisms

• epiphytic organisms live on prop roots:

sponges, tunicates, worms, anemones, snails, crabs, shrimp, lobster

Habitat Value:• some species live in mud:

crabs, mudskippers (Pacific)

Habitat Value:• many juvenile coral reef fish live

here (later move to reef)

• food and protection from predators among roots

Habitat Value:• many birds nest in branches

away from land predators:

egrets, doves, pelicans, etc

Zonation• four main types in Caribbean:

• red, black, white, buttonwood – moving inland

different types of mangroves

Red Mangrove• most prominent• large prop roots• anchor trees in soft mud• stabilize and trap

sediments• grow down from

branches into water• up to 30 ft. tall

Red Mangrove

• thick, waxy leaves - reduce water loss

• exclude salt at roots

Red Mangroves• pencil seeds - germinate while still

attached to the tree

• pointy – if low tide - falls into mud, sticks there, grows

• if high tide - floats to other areas

Black Mangroves• next inland

• snorkel roots – (pneumatophores)

- environment more severe than red mangrove

- anaerobic mud – high decomp.

- roots grow upward

- obtain oxygen from air above - act as straws

Black Mangroves

Black Mangroves• salt pores (glands) - secrete

excess salt from plant

• can sometimes see salt crystals - leaves covered with salt

White Mangroves• farthest from water• cannot tolerate

flooding

White Mangroves

• excrete salt from leaves and at base of stem – salt glands

Buttonwood• not true mangrove, but mangrove

associate

Human Uses

• protect coastal lands from storms and erosion, filter runoff

ex: tsunami

- where mangroves removed – land destroyed

- where mangroves remained – land protected

Human Uses• cutting to make charcoal

• honey from flowers

• medicine - from bark

• dyes - from bark

• cattle feed - leaves

Human Impacts• half of world’s mangroves destroyed –

more in Southeast asia• cut to make marinas - destroys habitat

and increases erosion

Human Impacts

• filled in land - for development

ex: St. Thomas racetrack built on filled in mangroves

• broken when boats tie to them

• cut for charcoal

Human Impacts• destroyed for shrimp mariculture –

for ponds

mangroves are a critical habitat to be restored