Shallow Lake Ecology Crooked Lake   Anoka County, MN   February 2008   Coon Creek Watershed District Wenck Associates, Inc.
Presentation Objectives <ul><li>Understanding Lake Ecology </li></ul><ul><ul><li>Physical Lake Properties </li></ul></ul><...
Crooked Lake Watershed
Physical Data Watershed area does not include the lake surface area
http://waterontheweb.org/under/lakeecology/index.html
What is a Shallow Lake? <ul><li>Generally, any lake that does not stay stratified throughout the summer season is a shallo...
Presentation Objectives <ul><li>Understanding Lake Ecology </li></ul><ul><ul><li>Physical Lake Properties </li></ul></ul><...
Aquatic Communities – Plankton & Fisheries
Lake Zones
 
Trophic Cascades Adapted from Metropolitan Council Environmental Services Pike Clear-water state Carp, minnows Invertebrat...
Biomanipulation of Fish Community – Round Lake, MN <ul><li>Rotenone was used to eliminate planktivorous fish in 1980 </li>...
Carp Exclusion
Crooked Lake Fish Community
Crooked Lake Fish Community
Refuge for small invertebrates (especially Cladocera) against fish predations AQUATIC PLANTS “ Services” to people through...
Typical Littoral Zone Vegetation Graphic from: Smith, R.L.  Elements of Ecology . 1992 Third Addition.
Crooked Lake Aquatic Vegetation
Presentation Objectives <ul><li>Understanding Lake Ecology </li></ul><ul><ul><li>Physical Lake Properties </li></ul></ul><...
Water Quality Drivers <ul><li>Nutrients </li></ul><ul><ul><li>Total phosphorus is a limiting nutrient  </li></ul></ul><ul>...
Trophic States in Lakes <ul><li>Hypereutrophic  - A very nutrient-rich lake characterized by frequent and severe nuisance ...
Relationship between TP and Transparency Oligotrophic  Mesotrophic  Eutrophic  Hyper- Eutrophic Total Phosphorus ( µ g/L)
MPCA Standards
Total Phosphorus and Chlorophyll-a Crooked Lake
Secchi Depth  Crooked Lake
Lake Response Models <ul><li>Internal Loading </li></ul><ul><ul><li>Nurnburg Approach for Sediment Anoxia </li></ul></ul><...
Phosphorus Sources
Lake Response Model
Presentation Objectives <ul><li>Understanding Lake Ecology </li></ul><ul><ul><li>Physical Lake Properties </li></ul></ul><...
Turbid and Clearwater States Competing Equilibria in Shallow Lakes <ul><li>Turbid State </li></ul><ul><ul><li>High algal p...
Shallow Lake Switches <ul><li>Drivers that cause a lake to shift from either the turbid or clear water state to the opposi...
More Development   (impervious surface)   = More Runoff
Invasive Species Curly-leaf Pondweed Purple Loosestrife Zebra Mussels Eurasian Watermilfoil
McComas, Unpublished data
Boating Impacts <ul><li>Boat wakes contribute to shoreline erosion </li></ul><ul><li>Prop disturbance  </li></ul><ul><ul><...
 
Shoreline  Development Impacts <ul><li>Additional runoff </li></ul><ul><ul><li>Nutrients, herbicides, pesticides </li></ul...
Crooked Lake Shoreline Characteristics
Presentation Objectives <ul><li>Understanding Lake Ecology </li></ul><ul><ul><li>Physical Lake Properties </li></ul></ul><...
Changing View of Lake Management <ul><li>OLD VIEW </li></ul><ul><li>Simple Cause Effect Relationship </li></ul><ul><ul><li...
Strategy for Restoring Shallow Eutrophic Lakes <ul><li>Forward switch detection and removal </li></ul><ul><li>External and...
Lake Response to Restoration
Lake Response to Restoration
Competing Management Goals
Design Strategy Implement Monitor Evaluate Assess Progress Adaptive Management
Implementation Depends on Cooperation <ul><li>Guide implementation through: </li></ul><ul><ul><li>Partnerships </li></ul><...
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2008 Shallow Lake Ecology Crooked Lake Annual Meeting

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Shallow Lake Ecology

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  • 2008 Shallow Lake Ecology Crooked Lake Annual Meeting

    1. 1. Shallow Lake Ecology Crooked Lake Anoka County, MN February 2008 Coon Creek Watershed District Wenck Associates, Inc.
    2. 2. Presentation Objectives <ul><li>Understanding Lake Ecology </li></ul><ul><ul><li>Physical Lake Properties </li></ul></ul><ul><ul><li>Biological Characteristics </li></ul></ul><ul><ul><li>Water Quality </li></ul></ul><ul><ul><ul><li>Drivers </li></ul></ul></ul><ul><ul><ul><li>Diagnostic Tools </li></ul></ul></ul><ul><ul><li>Shallow Lakes </li></ul></ul><ul><li>Introduction to Management Tools </li></ul>
    3. 3. Crooked Lake Watershed
    4. 4. Physical Data Watershed area does not include the lake surface area
    5. 5. http://waterontheweb.org/under/lakeecology/index.html
    6. 6. What is a Shallow Lake? <ul><li>Generally, any lake that does not stay stratified throughout the summer season is a shallow lake. </li></ul><ul><li>MPCA defines a shallow lake as lakes with a maximum depth of 15 feet or less, or with 80% or more of the lake area shallow enough to support emergent and submerged rooted aquatic plants. </li></ul>
    7. 7. Presentation Objectives <ul><li>Understanding Lake Ecology </li></ul><ul><ul><li>Physical Lake Properties </li></ul></ul><ul><ul><li>Biological Characteristics </li></ul></ul><ul><ul><li>Water Quality </li></ul></ul><ul><ul><ul><li>Understanding Drivers </li></ul></ul></ul><ul><ul><ul><li>Diagnostic Tools </li></ul></ul></ul><ul><ul><li>Shallow Lakes </li></ul></ul><ul><li>Introduction to Management Tools </li></ul>
    8. 8. Aquatic Communities – Plankton & Fisheries
    9. 9. Lake Zones
    10. 11. Trophic Cascades Adapted from Metropolitan Council Environmental Services Pike Clear-water state Carp, minnows Invertebrates Algae Submerged plants Sediment Resuspension Turbid-water state
    11. 12. Biomanipulation of Fish Community – Round Lake, MN <ul><li>Rotenone was used to eliminate planktivorous fish in 1980 </li></ul><ul><li>Restocked with Bass and walleye to control planktivores </li></ul><ul><li>Increase in water clarity for 2 years after manipulation </li></ul>Shapiro and Wright 1984
    12. 13. Carp Exclusion
    13. 14. Crooked Lake Fish Community
    14. 15. Crooked Lake Fish Community
    15. 16. Refuge for small invertebrates (especially Cladocera) against fish predations AQUATIC PLANTS “ Services” to people through bank edge protection against erosion, products, (reed, sedge, biomass, fish and fowl), amenity and conservation Absorb wind and wave energy, minimizing turbidity caused by sediment resuspension High production creates sediment conditions favoring nitrogen loss by denitrification and phosphate availability through release Food for invertebrates Food for adult fish Habitat, food cover and nesting materials for birds Provide habitat for attached algae Maintenance of clear water Maintenance of clear water Moss et al. 1996 Refuges for small fish against predators Cover and habitat for piscivorous fish Spawning habitat for fish
    16. 17. Typical Littoral Zone Vegetation Graphic from: Smith, R.L. Elements of Ecology . 1992 Third Addition.
    17. 18. Crooked Lake Aquatic Vegetation
    18. 19. Presentation Objectives <ul><li>Understanding Lake Ecology </li></ul><ul><ul><li>Physical Lake Properties </li></ul></ul><ul><ul><li>Biological Characteristics </li></ul></ul><ul><ul><li>Water Quality </li></ul></ul><ul><ul><ul><li>Water Quality Conditions and Drivers </li></ul></ul></ul><ul><ul><ul><li>Diagnostic Tools </li></ul></ul></ul><ul><ul><li>Shallow Lakes </li></ul></ul><ul><li>Introduction to Management Tools </li></ul>
    19. 20. Water Quality Drivers <ul><li>Nutrients </li></ul><ul><ul><li>Total phosphorus is a limiting nutrient </li></ul></ul><ul><ul><ul><li>The availability of phosphorus controls the amount of algal growth in a lake </li></ul></ul></ul><ul><ul><li>Nutrient source </li></ul></ul><ul><ul><ul><li>Stormwater runoff </li></ul></ul></ul><ul><ul><ul><li>Direct deposition from precipitation </li></ul></ul></ul><ul><ul><ul><li>Internal loading from lake sediments </li></ul></ul></ul><ul><ul><ul><li>Geese </li></ul></ul></ul><ul><ul><ul><li>Septic or Wastewater Discharge </li></ul></ul></ul>
    20. 21. Trophic States in Lakes <ul><li>Hypereutrophic - A very nutrient-rich lake characterized by frequent and severe nuisance algal blooms and low transparency. </li></ul><ul><li>Eutrophic - A high level of plant nutrients and biological productivity and low oxygen content. </li></ul><ul><li>Mesotrophic – A moderate level of nutrients and photosynthetic productivity. </li></ul><ul><li>Oligotrophic - nutrient-poor , low photosynthetic productivity. </li></ul>
    21. 22. Relationship between TP and Transparency Oligotrophic Mesotrophic Eutrophic Hyper- Eutrophic Total Phosphorus ( µ g/L)
    22. 23. MPCA Standards
    23. 24. Total Phosphorus and Chlorophyll-a Crooked Lake
    24. 25. Secchi Depth Crooked Lake
    25. 26. Lake Response Models <ul><li>Internal Loading </li></ul><ul><ul><li>Nurnburg Approach for Sediment Anoxia </li></ul></ul><ul><ul><ul><li>Calculate anoxic factor </li></ul></ul></ul><ul><ul><ul><li>Sediment release rate </li></ul></ul></ul><ul><ul><li>BATHTUB </li></ul></ul><ul><ul><ul><li>Annual model </li></ul></ul></ul>
    26. 27. Phosphorus Sources
    27. 28. Lake Response Model
    28. 29. Presentation Objectives <ul><li>Understanding Lake Ecology </li></ul><ul><ul><li>Physical Lake Properties </li></ul></ul><ul><ul><li>Biological Characteristics </li></ul></ul><ul><ul><li>Water Quality </li></ul></ul><ul><ul><ul><li>Understanding Drivers </li></ul></ul></ul><ul><ul><ul><li>Diagnostic Tools </li></ul></ul></ul><ul><ul><li>Shallow Lakes </li></ul></ul><ul><li>Introduction to Management Tools </li></ul>
    29. 30. Turbid and Clearwater States Competing Equilibria in Shallow Lakes <ul><li>Turbid State </li></ul><ul><ul><li>High algal productivity </li></ul></ul><ul><ul><li>Low aquatic plant productivity </li></ul></ul><ul><ul><li>Low grazer (zooplankton) productivity </li></ul></ul><ul><li>Clearwater State </li></ul><ul><ul><li>Large aquatic plant community </li></ul></ul><ul><ul><li>Low algal productivity </li></ul></ul><ul><ul><li>Large grazer population </li></ul></ul>Scheffer 2004
    30. 31. Shallow Lake Switches <ul><li>Drivers that cause a lake to shift from either the turbid or clear water state to the opposite state </li></ul><ul><ul><li>Clear scientific understanding of forward switches </li></ul></ul><ul><ul><li>Unclear understanding of reverse switches </li></ul></ul>
    31. 32. More Development (impervious surface) = More Runoff
    32. 33. Invasive Species Curly-leaf Pondweed Purple Loosestrife Zebra Mussels Eurasian Watermilfoil
    33. 34. McComas, Unpublished data
    34. 35. Boating Impacts <ul><li>Boat wakes contribute to shoreline erosion </li></ul><ul><li>Prop disturbance </li></ul><ul><ul><li>Especially in shallow areas </li></ul></ul><ul><ul><ul><li>Sediment scouring prevents plant establishment (Asplund and Cook 1997) </li></ul></ul></ul><ul><ul><li>Direct damage to plants </li></ul></ul><ul><ul><ul><li>Areas with boat traffic demonstrate lower biomass yields (Asplund & Cook 1997) </li></ul></ul></ul><ul><ul><li>Turbidity and light limitations </li></ul></ul><ul><ul><ul><li>Scientific understanding is limited </li></ul></ul></ul><ul><ul><li>Wave stress </li></ul></ul>
    35. 37. Shoreline Development Impacts <ul><li>Additional runoff </li></ul><ul><ul><li>Nutrients, herbicides, pesticides </li></ul></ul><ul><li>Overwater structures reduce light availability </li></ul><ul><li>Shoreline erosion </li></ul><ul><li>Loss of vegetation and habitat </li></ul><ul><ul><li>Lower songbird density (Lindsey et al. 2001) </li></ul></ul><ul><ul><li>Lower green from density (Woodford and Meyer 2002) </li></ul></ul><ul><ul><li>Loss or disturbance of fish spawning, feeding and rearing </li></ul></ul><ul><ul><ul><li>Loss of wood structure from tree fall </li></ul></ul></ul><ul><ul><li>Lower diversity of fish species in developed shoreline areas (Brazner 1997) </li></ul></ul><ul><ul><li>Reduction in vegetation abundance (66% Radomski 2005) </li></ul></ul>
    36. 38. Crooked Lake Shoreline Characteristics
    37. 39. Presentation Objectives <ul><li>Understanding Lake Ecology </li></ul><ul><ul><li>Physical Lake Properties </li></ul></ul><ul><ul><li>Biological Characteristics </li></ul></ul><ul><ul><li>Water Quality </li></ul></ul><ul><ul><ul><li>Understanding Drivers </li></ul></ul></ul><ul><ul><ul><li>Diagnostic Tools </li></ul></ul></ul><ul><ul><li>Shallow Lakes </li></ul></ul><ul><li>Introduction to Management </li></ul>
    38. 40. Changing View of Lake Management <ul><li>OLD VIEW </li></ul><ul><li>Simple Cause Effect Relationship </li></ul><ul><ul><li>Increased Phosphorus resulted in Decreased water quality </li></ul></ul><ul><li>NEW VIEW </li></ul><ul><li>Complex Adaptive Systems </li></ul><ul><ul><li>Hard to predict </li></ul></ul><ul><li>Focus on Adaptive Management </li></ul><ul><ul><li>Learn by doing </li></ul></ul><ul><ul><li>Diversity of knowledge </li></ul></ul>Dietz et al. 2003. Science.
    39. 41. Strategy for Restoring Shallow Eutrophic Lakes <ul><li>Forward switch detection and removal </li></ul><ul><li>External and internal nutrient control </li></ul><ul><li>Biomanipulation (reverse switch) </li></ul><ul><li>Plant establishment </li></ul><ul><li>Stabilizing and managing restored system </li></ul>
    40. 42. Lake Response to Restoration
    41. 43. Lake Response to Restoration
    42. 44. Competing Management Goals
    43. 45. Design Strategy Implement Monitor Evaluate Assess Progress Adaptive Management
    44. 46. Implementation Depends on Cooperation <ul><li>Guide implementation through: </li></ul><ul><ul><li>Partnerships </li></ul></ul><ul><ul><li>Programs </li></ul></ul><ul><ul><li>Activities </li></ul></ul><ul><ul><li>Areas </li></ul></ul><ul><li>Supports watershed planning: </li></ul><ul><ul><li>Enhanced description of water quality concerns </li></ul></ul><ul><ul><li>Improved understanding of key processes </li></ul></ul><ul><ul><li>Focus on solution development </li></ul></ul><ul><li>Adaptive Management </li></ul>

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