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PLHS Environmental Science
D. Blanck, MS
Lake Successionand Eutrophication
Trophic StatesOligotrophic
Mesotrophic
Eutrophic
Extinction
Characteristics of Trophic States
1. Shallow, sloping basin2. Relatively high
nutrients and org. matter3. Low hypolimnetic DO4. Low light penetration5. Rooted and emergent
veg.6. High phytoplankton
density7. High fertility
1. Deep, steep-sided basin2. Very low nutrients and
org. matter3. High hypolimnetic DO4. High light penetration5. Little or no rooted veg.,
periphyton in littoral6. Low phytoplankton
density7. Low fertility
EutrophicOligotrophic
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Oligotrophic diagram
Mesotrophic Diagram
Eutrophic Diagram
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The Eutrophication Process:Succession
1. Nutrient enrichment2. Increased organic matter production
• Increased growth transfers up the food chain3. Gradual filling of basin
• Sedimentation• Accumulation of slowly decomposing plants
(peat)4. Terrestrial plant invasion
NaturalLake
Succession
Natural succession depends on:1. Original basin shape
• Mean depth2. Nature of drainage basin
• Erosion rates• Soil composition → nutrient inputs• Hydrologic residence time
3. Climate• Rain and snowfall• Mean temperature
4. Geologic age
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Cultural (Human Induced)Eutrophication
1. Sources of nutrient enrichmenta. Municipal sewageb. Industrial wastesc. Agricultural fertilizersd. Detergents (phosphorous)e. Sediment from land clearing, road building,
land developmentf. Poor forest practices
CulturalEutrophication
A Lake Erie dock
Eutrophicationin the Great Lakes(Total Dissolved
Solids)
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It doesn’t just “go away”
Septic Tank Cutaway
Septic System
