Lake Succession
and Eutrophication
PLHS Environmental Science
D. Blanck, MS
Trophic States
Oligotrophic
Mesotrophic
Eutrophic
Extinction
Characteristics of Trophic States
Oligotrophic
1. Deep, steep-sided basin
2. Very low nutrients and
org. matter
3. High hypolimnetic DO
4. High light penetration
5. Little or no rooted veg.,
periphyton in littoral
6. Low phytoplankton
density
7. Low fertility
Eutrophic
1. Shallow, sloping basin
2. Relatively high
nutrients and org. matter
3. Low hypolimnetic DO
4. Low light penetration
5. Rooted and emergent
veg.
6. High phytoplankton
density
7. High fertility
1
Oligotrophic diagram
Mesotrophic Diagram
Eutrophic Diagram
2
The Eutrophication Process:
Succession
1. Nutrient enrichment
2. Increased organic matter production
•
Increased growth transfers up the food chain
3. Gradual filling of basin
•
•
Sedimentation
Accumulation of slowly decomposing plants
(peat)
4. Terrestrial plant invasion
Natural
Lake
Succession
Natural succession depends on:
1. Original basin shape
•
Mean depth
2. Nature of drainage basin
•
•
•
Erosion rates
Soil composition → nutrient inputs
Hydrologic residence time
3. Climate
•
•
Rain and snowfall
Mean temperature
4. Geologic age
3
Cultural (Human Induced)
Eutrophication
1. Sources of nutrient enrichment
a.
b.
c.
d.
e.
Municipal sewage
Industrial wastes
Agricultural fertilizers
Detergents (phosphorous)
Sediment from land clearing, road building,
land development
f. Poor forest practices
Cultural
Eutrophication
Eutrophication
in the Great Lakes
(Total Dissolved
Solids)
A Lake Erie dock
4
It doesn’t just “go away”
Septic Tank Cutaway
Septic System
5