Freshwater Ecosystems Chapter 7 Aquatic Ecosystems Section 1 Freshwater Ecosystems Ms. Mandel Environmental Science

Learning Targets I can describe the characteristics that are used to differentiate between the different types of aquatic ecosystems. I can differentiate between the different types of freshwater ecosystems.

Aquatic Ecosystems What factors determine which organisms live in the different aquatic ecosystems? Salinity Amount of dissolved salts in the water Temperature Sunlight Can only reach certain depths Oxygen Amount of DO (dissolved oxygen) Nutrients

Groups of Aquatic Organisms Plankton Drifters Phytoplankton – plants Zooplankton – animals May be microscopic or macroscopic (jellyfish)

Nekton Free-swimming organisms (fish, turtle, whales)

Benthos Bottom dwelling (mussels, worms, barnacles) Many live attached to hard surfaces

Do Aquatic Ecosystems Contain Decomposers? Yes Bacteria Fungi (microscopic) Marine worms Echinoderms Sea urchins Starfish Sea cucumbers

Freshwater Ecosystems

Freshwater A little more than 3% of all the water on the Earth is fresh water. Most is locked up in icecaps and glaciers.

Freshwater Rest is found in lakes rivers wetlands soil rock layers below surface in the atmosphere

Lakes

Structured Into Zones Littoral zone Near shore Great biodiversity Plants rooted in mud, but leaves above water

Benthic zone Bottom of lake Very little light Inhabited by decomposers, insect larvae & clams

How Do Nutrients Affect Lakes?

Eutrophication Increase in amount of nutrients in an aquatic ecosystem Leads to overgrowth of algae and plants Bacteria that feed on algae increase and use up dissolved O2 in lake Lack of O2 kills organisms that need it Is a natural occurrence, but can be increased by run-off of sewage, fertilizers or animal waste

Freshwater Wetlands

Covered with fresh water for at least part of the year bog marsh swamp Acidic soil, contains dead plant material, mosses and carnivorous pants Contain non-woody plants Dominated by woody plants

Environmental Functions of Wetlands Filtering water Flood protection Buffers shoreline from erosion Provide spawning grounds for animals Habitat for rare, threatened & endangered species Recreational areas

Human Impact on Wetlands Drained, filled and cleared for farms or development FL Everglades used to cover 8 million acres and now only cover 2 million acres Today - Laws and the federal gov’t protect many wetlands

Rivers

Where do they originate? Snow melt runoff Glaciers Is a river the same from where it starts to where it ends? No River – Old Age River – Youth Age

Life in a River Mosses Trout Minnows Crowfoot (plant) Catfish Carp Insect larvae Phytoplankton Zooplankton Etc

Rivers in Danger People use water from rivers for drinking, irrigating and in manufacturing. People dispose of garbage and sewage Dams alter the ecosystem they are in Pollution releases toxins into the water killing species and making fish unsuitable to eat

Learning Target Checkpoint What is the difference between a lake, freshwater wetlands and rivers?