Aquatic Ecosystems

Objectives:

1. Describe the characteristics of fresh water wetlands.

2. Define plankton, nekton, and benthos.

3. Describe human impacts on wetlands.

Fresh Water Ecosystems Only 3% of the Earth’s water is fresh

Organisms living in fresh water are grouped by their location

1.Plankton – drifting microscopic plants and animals (phytoplankton are basis of food chain)

Phytoplankton

Freshwater Ecosystems2. Nekton – free-swimming organisms like fish, turtles

and whales

Freshwater Ecosystems

3. Benthos – bottom-dwelling organisms such as mussels, worms, barnacles

Freshwater Ecosystems

Wetland (pg 188)– land that is sometimes covered with fresh water, usually located in the Southeastern US Marsh – dominated by non-woody plants

like cattails Swamp – dominated by woody plants like

trees

Freshwater Marsh

Freshwater Swamp

Wetlands

Trap and filter sediments, nutrients and pollutants, keeping them from entering reservoirs

Reduce the likelihood of flooding Buffer shorelines against erosion Provide habitat for commercial important fish

and shellfish Provide habitat for rare and threatened species Provide recreation

WetlandsHuman Impacts Residential and Commercial Development

6 million acres of the Everglades in South Florida were drained and filled for building

pg 206 pg 207

Pond or Lake

Pond or Lake

Littoral Zone – shallow water closest to shore, photosynthesis happens here

Limnetic Zone – layer of open water, nekton swim here, photosynthesis happens here

Profundal Zone – deeper, cold, dark water where light does not penetrate, nekton swim here

Benthic Zone – bottom, deep, cold, dark ground where decomposers are

Pond or Lake

Human Impacts Eutrophication – an increase in the amount of

nutrients (phosphates and nitrates) in an aquatic ecosystem caused by sewage, fertilizers or animal waste

Causes an excessive amount of algal growth and decay (algal bloom)

The algal bloom can produce toxins that kill animals

Causes a decreased level of oxygen which kills animals

Eutrophication

Eutrophication - Prevention and Reversal Oyster reefs filter out extra nutrients

Laws regulating the discharge of sewage

Educating farmers on fertilizer use

Eutrophication

Your town is planning to build a golf course. Golf courses use fertilizer and pesticides to keep the grass green and healthy. The city also intends to create lakes around the golf course. The lakes will be stocked with fish. The town hopes that fishermen will pay for fishing licenses and that this revenue will help the town pay for the sports programs at the high school.

Write a 10 sentence letter (minimum 75 words) to the city council describing your opinion on this plan. Use what you know about eutrophication to support your opinion. In addition, suggest a different idea that will fund the school’s sports program. Be prepared to read your letter out loud.