Freshwater Fragmentation Effects on Brown Trout

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Freshwater Fragmentation Effects on Brown Trout

• By Rowena Humphrey
• October 19, 2006

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Life History

• Two life-history tactics
• Stay in home freshwater stream
• Migrate downstream to the sea

Distribution
Salmo trutta L.
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Habitat
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Dams
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Consequences of Fragmentation

• Water Characteristics
• Mobility
• Vegetation
• Genetic Diversity
• Habitat Components

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Water Characteristics

• Water level
• Depth
• Temperature
• Velocity
• Discharge
• Turbidity
• Substrate

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Mobility

• Obstructions effect
• Isolation of the watershed
• Accessibility of tributaries
• Migration
• Difficulty depending on water level, location,
  and structure.

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Fish Ladders



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Vegetation

• Dramatically shifting vegetation
• Fluctuation between high production and mortality
  for terrestrial and aquatic plants

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Genetic Diversity
Reproductive Isolation Within Watersheds
Irregular Gene Flow
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Genetic Diversity
Reproductive Isolation Within Watersheds
Irregular Gene Flow
Decreased Diversity
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Conservation and Restoration

• Ineffective
• Single species
• Localized
• Individual obstructions

• Effective
• Multi-species
• Encompass all
• life-stages
• Movement
• Reconstruct the sequence and structure

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Conservation and Restoration

• Ineffective
• Single species
• localized
• individual obstructions

• Effective
• Multi-species
• encompass all
• life-stages
• Movement
• reconstruct the sequence and structure

Temporary solutions
Long-term solutions
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Sustainability

• Initial design
• Materials of construction
• Physical characteristics of the water systems
• Appropriate monitoring and maintenance programs

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Global effects on biodiversity
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Questions?