James A. Danoff-Burg, Columbia University, jd363@columbia.edu

Mangrove Forests

Worksheet (from supplemental reading in Nybakken)371-382 not 378-380Text Reading 109-111Video Questions “Creatures of the Mangrove”

James A. Danoff-Burg, Columbia University, jd363@columbia.edu

Mangrove Forests

• Found in coastal areas all over the tropics

• Primarily in brackish water– salty and fresh mix

• Cover approximately 22 million hectares in tropical and subtropical coasts

James A. Danoff-Burg, Columbia University, jd363@columbia.edu

Ecosystem Functions & Threats

• Serve as an important buffer between sea and land– Lessen impact of intense storms– Reduce erosion and increase sedimentation– Important coastal pioneer species– Act as basis for a complex, biologically diverse,

and productive ecosystem

• Increasingly threatened– Human development is most intense along

coasts

James A. Danoff-Burg, Columbia University, jd363@columbia.edu

• Lives in/on salt water.

• Prop-roots provide air for the plant and shelter for small fish and other marine animals.

James A. Danoff-Burg, Columbia University, jd363@columbia.edu

• Sand and silt causes the swamp to become more firm.

• This growth can continue until the island is big enough for people to take interest in it.

James A. Danoff-Burg, Columbia University, jd363@columbia.edu

• Mangroves get cut down to allow for sandy beaches and waterfront real estate.

• This destroys habitats and is severely detrimental to fisheries.

• Little Palm Island and resort replaces its beaches yearly with imported sand to make up for erosion caused by replacing its mangroves with palm trees but is still getting smaller.

James A. Danoff-Burg, Columbia University, jd363@columbia.edu

Mangroves

• Not a natural taxonomic group– Convergence among several groups

• Possibly 16 convergent events

– Based on physiological attributes– 54 species total world-wide

• 16 Families– Principally: Avicenniaceae & Rhizophoraceae– These two families include 25 spp.

• 20 Genera

James A. Danoff-Burg, Columbia University, jd363@columbia.edu

Mangrove Location

• Found in tropical areas only– Within the 20ºC isocline– More southern on East side of continents

• Due to southward moving warm Equatorial currents there

James A. Danoff-Burg, Columbia University, jd363@columbia.edu

Terminology(you have this from your reading so you

don’t have to write this)

• Mangal– Community of organisms in the mangrove

habitat

• Mangrove– Trees that flourish in the mangal

• Pneumatophore– Vertical root structures for air exchange

James A. Danoff-Burg, Columbia University, jd363@columbia.edu

Characteristics of Mangal

• Inundation with tides• Increasing salinity towards ocean• Sandy clay soil

– Nutrient poor

• Nitrogen & Phosphorus are limiting– Limiting mangrove growth only

• Organic nutrients deposited via siltation– Fresh water streams & down-shore currents– Most all are of terrestrial origin

• In sum: Mangal is a harsh place to live

James A. Danoff-Burg, Columbia University, jd363@columbia.edu

• Root networks catch more sand, silt, and mangrove seeds.

• This leads to dense patches.

James A. Danoff-Burg, Columbia University, jd363@columbia.edu

Mangrove Adaptations

• Salt tolerance – Sequester in tissue (bark, stem, root)– Secrete through leaves– Exclusion by negative hydrostatic pressure

• Frequent inundation– Aerenchyma tissue & aerial roots

• Tolerant of soils low in oxygen– Hypoxic or anoxic

James A. Danoff-Burg, Columbia University, jd363@columbia.edu

• Salt is directed to a few leaves that yellow and die.

James A. Danoff-Burg, Columbia University, jd363@columbia.edu

Mangrove Pollination

• Pollination method varies by species– Wind (Rhizophora)– bat or hawk moth (Sonneratia)– birds and butterflies (Bruguiera)– bees (Acanthus, Aegiceras, Avicennia,

Excoecaria, Xylocarpus)– fruit flies (Nypa)– other small insects (Ceriops, Kandelia)

James A. Danoff-Burg, Columbia University, jd363@columbia.edu

Mangrove Reproduction

• Vivipary normal– Reproduction and growth while still attached to

plant• Flowering• Fertilization• Propagule growth

Young propagule a.k.a. HypocotylHypocotyl

Mature propagule

James A. Danoff-Burg, Columbia University, jd363@columbia.edu

• Seeds sprout while still on the trees.

• They are transported by currents and tides to other suitable locations.

• This allows them to start growing as soon as they hit a shallow spot.

James A. Danoff-Burg, Columbia University, jd363@columbia.edu

Mangrove Dispersal

• Maturity -> Drop off maternal plant• Float horizontally initially

– Dispersal to novel environments ideally

• Float vertically with appropriate environmental conditions

• Rooting and growth

James A. Danoff-Burg, Columbia University, jd363@columbia.edu

Mangrove Species Zonation

Bruguiera gymnorrhiza

Ceriops australis

Avicennia marina

Rhizophora stylosa

SalinitySalinityInundationInundation

Decreasing Soil StabilityDecreasing Soil StabilitySedimentation RateSedimentation Rate

All increase toward shoreAll increase toward shore

James A. Danoff-Burg, Columbia University, jd363@columbia.edu

Most Common Species

• Red Mangrove (Rhizophora mangle)

• Black Mangrove (Avicennia germinans)

• White Mangrove(Laguncularia racemosa)

– All are found throughout tropics

James A. Danoff-Burg, Columbia University, jd363@columbia.edu

Bark Identification

James A. Danoff-Burg, Columbia University, jd363@columbia.edu

Tree Characters

James A. Danoff-Burg, Columbia University, jd363@columbia.edu

Pneumatophores

James A. Danoff-Burg, Columbia University, jd363@columbia.edu

Epiphytes

James A. Danoff-Burg, Columbia University, jd363@columbia.edu

James A. Danoff-Burg, Columbia University, jd363@columbia.edu

For more information

• Go to http://www.earthisland.org/map/mngec.htm and read the ecology link

• A clearinghouse on information on mangrove ecology is available at http://www.ncl.ac.uk/tcmweb/tcm/mglinks.htm