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Lakes & Rivers. Lake Nutrients. 3 categories of MN lakes Eutrophic- Mesotrophic (subcategory) Oligotrophic- Dystrophic-. Eutrophic Lakes. Lakes that are Usually very Clarity Oxygen levels Fish levels . Eutrophic lakes. Weeds and Good for Mud holds Slower
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Lake Nutrients • 3 categories of MN lakes • Eutrophic- • Mesotrophic (subcategory) • Oligotrophic- • Dystrophic-
Eutrophic Lakes • Lakes that are • Usually very • Clarity • Oxygen levels • Fish levels
Eutrophic lakes • Weeds and • Good for • Mud holds • Slower • Nutrients from river can
Eutrophic lakes • Sibley Lake • High • High levels of • Good • Fish reproduce when • Maybe
Oligotrophic Lakes • Lakes that are very • Little • Few • Usually • Clarity • Oxygen levels • Fish levels
oligotrophic lakes • Sand and • Not good for • Sand Loses • Filtration • Faster • Nutrients from river get
oligotrophic lakes • Pelican Lake • Cleaner • lower in • lower levels of • Poor • Fish reproduce • Maybe
Mestrophic Lakes • Lakes that are average in • Some • Some • Usually • Clarity • Oxygen levels • Fish levels
Dystrophic Lakes • Shallow lakes that get nutrients from the • Usually • High in hummus and • Organic • Contains many • Contains
Lake reproduction • Fish reproduction is tied to
Lake reproduction • High nutrient lakes • Fish • Lay • Eggs • Smaller • Usually
Lake reproduction • Low nutrient lakes • Fish • Lay • Eggs are • Larger • Usually
Invasive species • How many animal invasive species does the DNR list for MN lakes?
Invasive species • 16 • http://www.dnr.state.mn.us/invasives/aquaticanimals/index.html
currents • Lakes have currents just • They have both • Movement based on
Horizontal currents • Seiches • Water moves back and forth from • Surface water can slide across the • Thermocline separates layers of
Horizontal currents • Larger seiches can occur • Help • http://www.lakesuperiorstore.com/resources/glinfo.htm
Circular currents • Langmuir circulations • Consist of alternating • Traps
Vertical currents • Usually based on • Disappearance of the
Nutrient mixing • Lakes are grouped by the movement of water from top to bottom that mixes the nutrients. • 4 mixing groups
Nutrient mixing • Lake water mixes when the temperature is close to the • Lake temperatures that vary greatly create a • The thermoclines do not allow certain water • If water does not mix oxygen and nutrition can not
Oligomitic Lakes • Oligomitc lakes • Surface water never
Polymitic Lakes • Polymitic Lakes • Weather can change rapidly to allow
Monomitic Lakes • Monomitic • North • Great Lakes in • Usually short summers so water never
Dimitic Lakes • Dimitic Lakes • Usually mix in • Summer & winter temperatures create
Lake Zones • Lakes have different area that are used for . • Not all lakes have • Lakes eco-regions can play a role in the type and • MN has
Littoral Zones • Littoral Zone • From the shoreline to • Most important zone for • Larger the littoral zone the
Limnetic Zone (open water) • Limnetic Zone Area of lake where there is no influence • This area can be • Long thin Lake with • It can be • Shallow shoreline
Benthic Zone • Benthic Zone has • Depth is usually • May depend on • No • No • Depends on
Euphotic zone • Euphotic zone is • More of a • Lots of
Lake eco-regions • MN has • Eco-region is based on the plants and soil • 98% of MN lakes are in
Eco-Regions • 1) Northern MN wetland • 2) Red River Valley • 3) Northern lakes and forest • 4) North central Hardwoods • 5) Northern glaciated plains • 6) Western corn belt plains • 7) Driftless Area