Mangrove%20Ecology

1
Mangrove Ecology

• with a case study from Ecuador

Introduction to Coastal Management
2
Mangrove or Mangal
Red Mangroves (Rhizophora mangle)

• Develop only on shorelines protected from wave
  action (estuaries, bays, lagoons)
• Common throughout the tropical regions of the
  world
• Typically flooded once or twice per day

• Definition
• Tropical hardwood trees adapted to grow in marine
  intertidal environments

3
Distribution of Mangroves

• Generally occur between 30 degrees N.L. and 30
  degrees S.L.
• Generally follow the 24 degree C. (75 degrees F.)
  isotherm of sea surface temperature
• Tolerate little or no frost
• Uncommon along arid coasts

Distribution of mangroves (green) in southern
North American and Northern South America
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Mangrove or Mangal Characteristics

• Low diversity of plant and animal species
• Canopy high and monotonous
• Soils waterlogged and anaerobic
• Substrate variable (muds, sand, rock, organic)

5
Mangrove or Mangal Characteristics

• Mangrove species show characteristics of pioneer
  species in their reproductive biology
• r-selection properties in finding a habitat
• Mangrove species show characteristics of mature
  phase species in aspects of community structure
  and vegetative growth
• K-selection properties in maintaining habitat

6
Mangrove Specializations

• Most species have some part of root system
  exposed to atmosphere
• Leaves large, thick, leathery and evergreen
• Many are capable of excreting salts from leaves
• Most cannot be propagated vegetatively
• Most have no growth rings
• All mangroves distributed by water and propagules
  float

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Mangrove Characteristics
Frigate Bird (Fregata magnificens)

• Fauna
• highly variable not characteristic
• insects common
• birds--few
• mud skippers, crabs, oysters, snails
• crocodiles, snakes (few poisonous)
• tiger (Ganges River mangal is refuge)
• deer, raccoon, bats (bats are visitors)

White-tailed Deer (Odocoilus ____)
Raccoon (Procyon lotor)
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Mangrove Characteristics

• Once the mangrove becomes established
• little structure to the community
• succession not documented
• no understory
• no stratification
• species distributed by edaphic factors (soil
  type, soil salinity)

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Utilization and Exploitation of Mangroves

• Forestry
• boat building an fish traps
• poles
• firewood (charcoal)
• tannins and dyes
• chip and sell as cellulose base

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Utilization and Exploitation of Mangroves

• Agriculture
• typical agricultural plants cannot survive in
  mangrove environments
• rice fields
• mariculture (shrimp, finfish, shellfish)

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Utilization and Exploitation of Mangroves

• Fisheries
• documented as nutrient source for nearshore
  fisheries
• stabilize shorelines reduce sedimentation into
  estuaries
• habitat for juvenile fish
• habitat for oysters and shellfish

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Utilization and Exploitation of Mangroves

• Salt conversion
• Sewage treatment (garbage dump)
• Coastal protection (storm buffer, stabilize
  shoreline)
• Wildlife management (deer, crocodiles, tigers)

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Ecuadorian Shrimp Mariculture

• Shrimp farming developed in the late 1960s
• By 1982, 44 of fish exports were shrimp

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Shrimp Exports to the United States from Ecuador,
Panama and Mexico (1977-82)
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Tradeoffs for Intensive versus Extensive
Mariculture
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Solutions?

• Intensify mariculture to increase yields
• Discourage location of ponds in mangroves
• Train extension agents
• Link research and field applications
• Discourage international funding for new sites
• Charge single agency with mariculture management