Freshwater Ecosystems

* Prepare yourself, there are 35 slides!

Freshwater Ecosystems

• Only covers 3% of Earth’s surface

• What makes them different?

Abiotic Factors• Water Speed / flow

• Depth

• Temperature

• Chemistry (salinity)

Organisms

• Grouped by location & adaptations

• 3 groups

1 - Plankton• Float near the surface

• Phytoplankton – single celled algae; produce most of the food for an aquatic ecosystem

• Zooplankton – microscopic animals

2 - Nekton

• Free swimming

• Ex. fish & turtles

3 - Benthos

• Bottom dwelling

• Most live attached to hard surfaces

• Ex. mussels, worms & barnacles

Lakes – 5 Types!

• 1- Glacial lake: formed by depressions in the surface

• 2- Barrier lakes: formed from landslides

• 3- Crater lakes: volcanoes

• 4- Tectonic lakes: formed from rift valleys

• 5- Artificial lakes: humans (dams) & beavers

Ponds

Zones

Littoral Zone• Shore

• Nutrient rich

• Diverse & abundant life

Benthic Zone• No light

• Decomposers, insect larvae & clams

Animal Adaptations

• Water beetles – hair to trap air

• Catfish – whiskers to sense

• Amphibians – burrow in the cold

Eutrophication

• Increase in the amount of plant growth due to nutrients

• ↑algae = ↑bacteria = ↓oxygen

• Occurs naturally over long time

• Accelerated by run-off

Wetlands• Covered with fresh water for part

of year

• Traps & filters pollutants (keeping them out of cycle)

• Reduces chances of flood

• Prevents erosion

• Provides spawning ground & habitats

• Provides recreational areas

• 2 types

Marsh• Treeless

• Low, flat lands

• Characterized by salinity

• Brackish Marsh – slight NaCl

• Salt Marsh – more NaCl

Swamp• Has Trees

• Flat, poorly drained land

• Near streams

• Mangrove – near ocean

Human Impact on the Wetlands

• Drained, filled, cleared

• Farms, residential & commercial development

• Florida Everglades – from 8 million to 2 million acres

Stream

Rivers

Rivers

• Many originate from snow capped mountains

• Flows, broadens to become slower, warmer & wider

• Mosses anchor in the flow

River problems• Industrial pollution

• Kills organisms

• Makes fish inedible

• Carries pollution in the run-off

• Dams alter ecosystems

Brainpop: Rivers