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1. The 3 zones in a river are...2. Identify one river zone and list 2

biological and 2 physical characteristics.

3. Identify one river zone and one species of fish that survives best in that zone. Explain why that species is adapted to that zone.

LAKES and PONDSLAKES and PONDS

Formation of Lakes – Great Formation of Lakes – Great LakesLakesThe Great Lakes did not exist in preglacial times

but are the cumulative result of several phases of glaciation that took place during the last 1.5 million years.

Ice-marginal lakes (or proglacial lakes) form when the land in front of the ice slopes toward the ice, allowing meltwater to pond directly in contact with the ice, as shown below

Drainage continued southward to the Gulf of Mexico.

The present-day Great Lakes formed as the earth’s crust, depressed from the weight of the ice sheets, rebounded after deglaciation.

Formation of Lakes - Formation of Lakes - VolcanoesVolcanoesCrater Lake (Oregon) was formed after

the collapse of an ancient volcano, named Mount Mazama.

This volcano violently erupted approximately 7700 years ago. That eruption was 42 times as powerful as the 1980 eruption of Mount St. Helens.

Lentic EcosystemsLentic EcosystemsLakes differ from ponds on the

depth and amount of water.Plants and animals are

distributed within ponds and lakes according to depth of water and distance from shore.

Usually ponds will have sunlight reaching the bottom all the way across the entire body of water.

ZONES of LakesZONES of LakesLittoral zone- a shallow well

lighted area with warm water that is close to shore and hosts emergent plants.

This area is the most diverse with algae, snails, insects, fish, amphibians, reptiles and mammals.

Fig. 8-15, p. 175

Sunlight

Painted turtle

Blue-winged teal

Green frog

Muskrat

Pond snail

Littoral zone Plankton

Limnetic zoneProfundal zoneDiving beetle Benthic zone

Northern pike

Yellow perch Bloodworms

Limnetic ZoneLimnetic ZoneWell lighted area with open

surface of water farthest from the shore.

Also known as the epilimnion.Occupied by plankton, fish and

some reptiles.Littoral zone

Plankton

Limnetic zoneProfundal zone

Benthic zone

Northern pike

Yellow perch

Profundal zoneProfundal zone

Also known as the hypolimnion.Deep aphotic region.

◦Aphotic- no light penetration.

Littoral zone

Plankton

Limnetic zoneProfundal zone

Benthic zone

Northern pike

Yellow perch Bloodworms

Benthic ZoneBenthic ZoneBottom of aquatic ecosystems.Nutrients are delivered to this area

in the form of detritus.Detritus is the dead organic matter

that “rains” down from upper areas.Has many decomposers and also

fish, clams, mussels, etc.

Lake and Pond SuccessionLake and Pond SuccessionOLIGOTROPHIC - are generally

clear, having a low concentration of plant life. Typically glacial lakes

MESOTROPHIC - have good clarity and an average level of nutrients.

EUTROPHIC - are enriched with nutrients, resulting in good plant growth and possible algal blooms. Older ponds.

Eutrophication - the speeding up of pond succession due to fertilizer runoff from agriculture.