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Limnology - UWSPLimnology An Introduction Susan Knight April 2019 Lakes Streams Groundwater Wetlands...

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Limnology An Introduction Susan Knight April 2019
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Page 1: Limnology - UWSPLimnology An Introduction Susan Knight April 2019 Lakes Streams Groundwater Wetlands Physics Chemistry Biology So many lakes, so little time Why do Neighboring Lakes

Limnology

An Introduction

Susan Knight April 2019

Page 2: Limnology - UWSPLimnology An Introduction Susan Knight April 2019 Lakes Streams Groundwater Wetlands Physics Chemistry Biology So many lakes, so little time Why do Neighboring Lakes

Lakes Streams

Groundwater Wetlands

Physics Chemistry Biology

Page 3: Limnology - UWSPLimnology An Introduction Susan Knight April 2019 Lakes Streams Groundwater Wetlands Physics Chemistry Biology So many lakes, so little time Why do Neighboring Lakes

So many lakes, so little time

Page 4: Limnology - UWSPLimnology An Introduction Susan Knight April 2019 Lakes Streams Groundwater Wetlands Physics Chemistry Biology So many lakes, so little time Why do Neighboring Lakes

Why do Neighboring Lakes Differ?

• Lake Area: tiny to >3000 acres

• Chemistry• Landscape position• Nutrients, especially phosphorus• Susceptible to Acidification

• Color: Blue, Green, and Brown

• Water Clarity: Clear to Not Clear

• Boat Use: Crowded to Uncrowded

• Number of Fish Species: 0 to 37

Page 5: Limnology - UWSPLimnology An Introduction Susan Knight April 2019 Lakes Streams Groundwater Wetlands Physics Chemistry Biology So many lakes, so little time Why do Neighboring Lakes

Individual Lake vs Landscape Perspective

Page 6: Limnology - UWSPLimnology An Introduction Susan Knight April 2019 Lakes Streams Groundwater Wetlands Physics Chemistry Biology So many lakes, so little time Why do Neighboring Lakes

Magnuson et al. 2006

Balance of precipitation, groundwater and stream inputs matters to lake physics, chemistry, biology

Where does the water come from?

Page 7: Limnology - UWSPLimnology An Introduction Susan Knight April 2019 Lakes Streams Groundwater Wetlands Physics Chemistry Biology So many lakes, so little time Why do Neighboring Lakes

Important elements and compounds…

•Oxygen•Phosphorus•Nitrogen•Alkalinity•Conductance•pH (acidity)•Water (especially odd)

Page 8: Limnology - UWSPLimnology An Introduction Susan Knight April 2019 Lakes Streams Groundwater Wetlands Physics Chemistry Biology So many lakes, so little time Why do Neighboring Lakes

…are inextricably linked to biological processes

• Primary Productivity: Growth of phytoplankton and plants

• Zooplankton, Invertebrates

• Forage Fish• Large Fish

Page 9: Limnology - UWSPLimnology An Introduction Susan Knight April 2019 Lakes Streams Groundwater Wetlands Physics Chemistry Biology So many lakes, so little time Why do Neighboring Lakes

Nutrients in lakes

Phosphorus• Most often the limiting nutrient

in lakes

• More P often means more algae

• More algae often means greener water

• Greener water often means impaired water

Nitrogen• Lakes less often N limited

• Some cyanobacteria can fix N, making it available for uptake by algae and other primary producers

• In lakes with plenty of P, may get N-fixing cyanobacteria (blue-green) blooms

Page 10: Limnology - UWSPLimnology An Introduction Susan Knight April 2019 Lakes Streams Groundwater Wetlands Physics Chemistry Biology So many lakes, so little time Why do Neighboring Lakes

StratificationDeep lakes form layers of different temperatures,

densities in summer and winter

Page 11: Limnology - UWSPLimnology An Introduction Susan Knight April 2019 Lakes Streams Groundwater Wetlands Physics Chemistry Biology So many lakes, so little time Why do Neighboring Lakes

Deep (>18-20’ ) lakes usually stratify and turnover twice a year

Shallow lakes (<18’ ) do not stratify and mix frequently

Page 12: Limnology - UWSPLimnology An Introduction Susan Knight April 2019 Lakes Streams Groundwater Wetlands Physics Chemistry Biology So many lakes, so little time Why do Neighboring Lakes

…More on stratification and phosphorus

1. There may be no oxygen at the bottom of a lake in late summer.

2. When there is no oxygen, the phosphorus is not bound to iron, and the phosphorus is free for uptake.

3. When a stratified lake turns over in spring and fall, phosphorus-rich and oxygen-poor water at the bottom circulates and may cause algal blooms (internal loading).

4. Shallow lakes mix frequently, and have a different phosphorus dynamic than deep lakes.

Page 13: Limnology - UWSPLimnology An Introduction Susan Knight April 2019 Lakes Streams Groundwater Wetlands Physics Chemistry Biology So many lakes, so little time Why do Neighboring Lakes

Littoral zone – area where plants are growing, shallow waterBenthic zone – bottomPelagic area – deep or open water (limnetic zone)

Lake zones

Page 14: Limnology - UWSPLimnology An Introduction Susan Knight April 2019 Lakes Streams Groundwater Wetlands Physics Chemistry Biology So many lakes, so little time Why do Neighboring Lakes

Littoral Zone

Page 15: Limnology - UWSPLimnology An Introduction Susan Knight April 2019 Lakes Streams Groundwater Wetlands Physics Chemistry Biology So many lakes, so little time Why do Neighboring Lakes

Wood, plants, and algae in the littoral zone are very important to the lake ecosystem.

Page 16: Limnology - UWSPLimnology An Introduction Susan Knight April 2019 Lakes Streams Groundwater Wetlands Physics Chemistry Biology So many lakes, so little time Why do Neighboring Lakes

Food Webs

• Photosynthesis = 1º production

CO2 + H2O → Sugar +O2

• Photosynthesis by algae, plants

• Zooplankton eat algae

• Small fish eat zooplankton

• Large fish eat smaller fish

• Larger fish eaters eat large fish Trophic Cascade

Page 17: Limnology - UWSPLimnology An Introduction Susan Knight April 2019 Lakes Streams Groundwater Wetlands Physics Chemistry Biology So many lakes, so little time Why do Neighboring Lakes

Trophic state

Describes productivity

Page 18: Limnology - UWSPLimnology An Introduction Susan Knight April 2019 Lakes Streams Groundwater Wetlands Physics Chemistry Biology So many lakes, so little time Why do Neighboring Lakes

Trophic state

Page 19: Limnology - UWSPLimnology An Introduction Susan Knight April 2019 Lakes Streams Groundwater Wetlands Physics Chemistry Biology So many lakes, so little time Why do Neighboring Lakes

Trophic state

Page 20: Limnology - UWSPLimnology An Introduction Susan Knight April 2019 Lakes Streams Groundwater Wetlands Physics Chemistry Biology So many lakes, so little time Why do Neighboring Lakes

A few important lake issues

•Human-caused Eutrophication• Invasive Species• Climate Change• Shoreland Destruction• Pollution• Lake level changes

Page 21: Limnology - UWSPLimnology An Introduction Susan Knight April 2019 Lakes Streams Groundwater Wetlands Physics Chemistry Biology So many lakes, so little time Why do Neighboring Lakes

A few important lake issues

• Human-caused Eutrophication

• Invasive Species• Climate Change• Shoreland Destruction• Pollution• Lake level changes

Page 22: Limnology - UWSPLimnology An Introduction Susan Knight April 2019 Lakes Streams Groundwater Wetlands Physics Chemistry Biology So many lakes, so little time Why do Neighboring Lakes

A few important lake issues

•Human-causedEutrophication• Invasive Species• Climate Change• Shoreland Destruction• Pollution• Lake level changes

Eurasian water-milfoil

Curly-leaf pondweed

Page 23: Limnology - UWSPLimnology An Introduction Susan Knight April 2019 Lakes Streams Groundwater Wetlands Physics Chemistry Biology So many lakes, so little time Why do Neighboring Lakes

A few important lake issues

•Human-caused Eutrophication• Invasive Species• Climate Change• Shoreland Destruction• Pollution• Lake level changes

Zebra mussels

Spiny water fleas

Page 24: Limnology - UWSPLimnology An Introduction Susan Knight April 2019 Lakes Streams Groundwater Wetlands Physics Chemistry Biology So many lakes, so little time Why do Neighboring Lakes

A few important lake issues

•Human-causedEutrophication• Invasive Species• Climate Change• Shoreland Destruction• Pollution• Lake level changes

Page 25: Limnology - UWSPLimnology An Introduction Susan Knight April 2019 Lakes Streams Groundwater Wetlands Physics Chemistry Biology So many lakes, so little time Why do Neighboring Lakes

Temperature is an ecological “master factor”

Water Temperature

Nutrient cycling

NP

Growth, Survival, Reproduction

Why is Climate Change Important in Lakes?

Page 26: Limnology - UWSPLimnology An Introduction Susan Knight April 2019 Lakes Streams Groundwater Wetlands Physics Chemistry Biology So many lakes, so little time Why do Neighboring Lakes

Temperature is vitally important for

fish

Species ‘thermal niche’

Determines metabolic and other rates

Page 27: Limnology - UWSPLimnology An Introduction Susan Knight April 2019 Lakes Streams Groundwater Wetlands Physics Chemistry Biology So many lakes, so little time Why do Neighboring Lakes

A few important lake issues

• Cultural Eutrophication

• Invasive Species

• Climate Change

• Shoreland Destruction

• Pollution

•Lake level changes

Page 28: Limnology - UWSPLimnology An Introduction Susan Knight April 2019 Lakes Streams Groundwater Wetlands Physics Chemistry Biology So many lakes, so little time Why do Neighboring Lakes

A few important lake issues

• Cultural Eutrophication

• Invasive Species

• Climate Change

• Shoreland Destruction

• Pollution

• Lake level changes

Page 29: Limnology - UWSPLimnology An Introduction Susan Knight April 2019 Lakes Streams Groundwater Wetlands Physics Chemistry Biology So many lakes, so little time Why do Neighboring Lakes

A few important lake issues

• Cultural Eutrophication• Invasive Species• Climate Change• Shoreland Destruction• Pollution• Lake level changes

• Natural cycles• Climate change causes

Page 30: Limnology - UWSPLimnology An Introduction Susan Knight April 2019 Lakes Streams Groundwater Wetlands Physics Chemistry Biology So many lakes, so little time Why do Neighboring Lakes

13

Questions?


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