Chapter 7 Aquatic Ecosystems Environmental Science Spring 2011

Chapter 7.1 Freshwater Ecosystems

Aquatic Ecosystems Types of organisms determined by salinity – Salinity: amount of dissolved salts in water Divided into freshwater and marine Banff National ParkHawaii

Aquatic Ecosystems Temperature, sunlight, oxygen, nutrients all play a role in where organisms live

Aquatic Ecosystems Organisms that live in aquatic ecosystems are grouped by their location and adaptations 1.Plankton: cannot swim against currents; drifters A.Phytoplakton: drifting plants, food base for most aquatic organisms, majority are microscopic

Aquatic Ecosystems 1.Plankton: A.Zooplankton: drifting animals, may be microscopic or as large as a jellyfish

Aquatic Ecosystems 2.Nekton: free swimming organism such as fish, turtles, and whales 3.Benthos: bottom dwelling organisms, many live attached to hard surfaces – Ex. Muscles, worms, barnacles

Lakes and Ponds Littoral Zone: nutrient rich, near the shore, aquatic life diverse and abundant Plants: – Cattails and reeds rooted in mud underwater, upper leaves and stem emerge from water – Lilies are plants that have floating leaves

Lakes and Ponds Further from shore, no rooted plants Phytoplankton here make own food from photosynthesis

Lakes and Ponds Some lakes have areas so deep that there is too little light for photosynthesis Bacteria and other decomposers live on dead plants and animals that drift down from above Fish adapted to cold water can live here as well

Lakes and Ponds Benthic Zone: bottom of pond or lake Inhabited by decomposers, insect larvae, and clams

Lakes and Ponds Animals have adaptations to help them get what they need to survive

Lakes and Ponds Eutrophication: increase in the amount of nutrients in an aquatic ecosystem Eutrophic lake: lake with large amount of algae and plant growth due to nutrients – Less oxygen due to decomposition – Kills organisms needing oxygen – Runoff accelerates eutrophication

Lakes and Ponds

Freshwater Wetlands Freshwater wetlands: areas of land that are covered with freshwater for at least part of the year – Marshes – Swamps

Freshwater Wetlands Marshes: contain nonwoody plants – Cattails, etc.

Freshwater Wetlands Swamps: dominated by woody plants – Trees, shrubs, etc.

Freshwater Wetlands Wetlands perform several important environmental functions Act as filters, remove pollutants from the water Improve water quality, control flooding (absorb extra water) Fish use wetlands for spawning Vegetation traps carbon

Freshwater Wetlands: Marshes Most located in Southeast Florida Everglades: largest freshwater wetland Tend to occur on low, flat lands and have little water movement

Freshwater Wetlands: Marshes Benthic zone in marshes: nutrient rich and contain plants, numerous types of decomposers, and scavengers Marshes attract many migratory birds

Freshwater Wetlands: Marshes Salinity: varies – Some slightly salty (brackish) water – Others salty as ocean water Organisms adapted to range of salinity

Freshwater Wetlands: Swamps Swamps: occur on flat, poorly drained land, often near streams Species depend on salinity of water and climate of area

Human Impact on Wetlands Wetlands previously thought of as wastelands that provide breeding ground for disease carrying insects Many have been drained and filled Important role of wetlands as purifiers of wastewater and flood protection Vital habitats for wildlife

Rivers Headwaters: cold and full of oxygen, runs swiftly though a shallow riverbed Normally originates from snowmelt in mountains, as flows down mountain becomes warmer, wider, and slower containing more vegetation and less oxygen

Rivers Life in a River – Plants and animals are adapted to different areas of the river