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Aquatic Ecosystems. Freshwater Mr. Stecher 7.1. Freshwater Ecosystems. Include: lakes/ponds, rivers, streams, wetlands, and marshes. Any FRESH water. . Aquatic Organisms. Grouped by location and adaptations. 1. Plankton – organisms that cannot swim against currents (drifters).
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Aquatic Ecosystems Freshwater Mr. Stecher 7.1
Freshwater Ecosystems Include: lakes/ponds, rivers, streams, wetlands, and marshes. Any FRESH water.
Aquatic Organisms Grouped by location and adaptations. 1. Plankton – organisms that cannot swim against currents (drifters). 2. Nekton – Free swimming organisms (fish, whales) 3. Benthos – Bottom-dwelling mussels, worms, and barnacles.
Lakes and Ponds Littoral Zone: near the shore. It has rich aquatic life, including plants (cattails and reeds) Limnetic Zone: farther from shore with no rooted plants. Benthic Zone: the bottom of the lake, cool and dark, inhabited by decomposers, insect larvae, and clams.
Eutrophication An increase in the amount of nutrients resulting in an increase in plant and algae growth. More algae = More decay by bacteria that consume oxygen (O2) = less dissolved oxygen available = all fish die Runoff from farms and other sources of fertilizers accelerates eutrophication.
Freshwater Wetlands • Functions: • act as filters, removing pollutants and cleaning water for lakes and rivers downstream. • Control flooding by absorbing extra water when rivers overflow. • Buffer shorelines against erosion • Provide spawning grounds for fish and shellfish • Habitat for endangered species • Recreational areas for fishing, birdwatching, hiking, etc.
Freshwater Wetlands continued • 2 types: • 1. Marshes: • Contain non-woody plants like cattails and water lilies. • 2. Swamps • Dominated by woody plants, like flood-tolerant trees and shrubs.
Marshes Generally occur in SE United States Have nutrient rich benthic zones and serve as important habitat for waterfowl and fish. Salinity varies from fresh water to salty ocean water marshes.
Swamps Occur on flat, poorly drained wooded land. Plant species vary with climate and salinity of water. Can be either acidic bogs or alkaline fens. Great habitat for reptiles (alligators), amphibians, birds, and fish.
Human Impact Some wetlands have been drained for farmland – remember the nutrient-rich benthic zone? Some have been drained for commercial development. Many wetlands are now protected and allowed to serve their purpose as important environmental filters and habitat.
Rivers Originate from springs or snow melt or where smaller streams merge together. Start with clean oxygenated water and as you go further downstream the water becomes deeper, contains more sediment and slows down. Human uses affect rivers. We take water from rivers for irrigation and drinking water and often return sewage, runoff, and garbage.
