Objectives

1. Objectives • Describethe factors that determine where an organism lives in an aquatic ecosystem. • Describethe littoral zone and the benthic zone that make up a lake or pond. • Describetwo environmental functions of wetlands. • Describeone threat against river ecosystems.

2. Freshwater Ecosystems • ponds, lakes, streams, rivers, and wetlands. • wetlands - areas of land that are periodically under water or whose soil contains a great deal of moisture.

3. Characteristics of Aquatic Ecosystems • temperature, sunlight, oxygen, and nutrients determine organisms • organisms grouped by location and adaptations.

4. Groups • Plankton- mass of mostly microscopic organisms that float or drift freely in the water, include zooplankton phytoplankton. • Nekton- swim actively in open water • Benthos- bottom-dwelling organisms, often attached to hard surfaces.

5. Lakes, Ponds • lakes, ponds, form naturally where groundwater reaches the Earth’s surface. • artificial lakes used for power, irrigation, water storage, and recreation. • structured into horizontal and vertical zones that depend on the amount of sunlight available.

6. Life in a Lake • littoral zone- shallow zone with light, plant and aquatic life diverse and abundant. • some plants rooted in the mud with upper leaves, stems above water or floating leaves.

7. Life in a Lake • deep areas have to little light for photosynthesis. • bacteria, fish adapted to cooler, darker water • benthic zone- region near the bottom of a pond, lake or ocean inhabited by decomposers, insect larvae, and clams.

8. Life in a Lake • in regions where lakes partially amphibians burrow into the littoral mud to avoid freezing

9. A Lake Ecosystem

10. How Nutrients Affect Lakes • Eutrophication - increase amount of nutrients, such as nitrates, in an aquatic ecosystem. • amount of plants and algae grow, so the number of bacteria feeding decaying organisms grows. • use the oxygen reducing amount • kills oxygen loving organisms.

11. How Nutrients Affect Lakes • lake with large amounts of plant growth eutrophic • naturally become eutrophic over time • eutrophication can be accelerated by runoff, that can carry sewage, fertilizers, or animal wastes into water

12. Freshwater Wetlands • areas of land covered with fresh water for part of the year. • two main types • marshes contain nonwoody plants • swamps dominated by woody plants. • most freshwater wetlands located in the southeastern United States, largest (Florida Everglades).

13. Freshwater Wetlands

14. Freshwater Wetlands • perform several important environmental functions. • act like filters or sponges that absorb and remove pollutants from the water. • control flooding by absorbing extra water when rivers overflow. • provide a home for native and migratory wildlife • feeding, spawning area for many freshwater game fish.

15. Marshes • occur on low, flat lands with little water movement. • plant roots in sediments, leaves out on surface of the water year-round. • Marshes characterized salinity. • brackish: slightly salty • salt marshes: saltier water.

16. Marshes • benthic zones nutrient rich with plants, decomposers, and scavengers. • water fowl, birds - adapted for fish and insects • migratory birds from temperate and tropical habitats.

17. Swamps • occur on flat, poorly drained land • often near streams dominated by woody shrubs, water loving trees • ideal habitat for amphibians • birds attracted to hollow trees near or over the water • reptiles are the predators

18. Human Impact on Wetlands • previously considered wastelands, breeding grounds for insects. • many drained, filled, and cleared for development laws now protect many wetlands

19. Rivers • at headwaters- usually cold, full of oxygen, runs swiftly through shallow riverbed • as flows down (mountain), may broaden, become warmer, wider, slower, decrease in oxygen. • change with the land and climate through which it flows

20. Life in a River • near the headwater, mosses anchor to rocks • trout, minnows adapted to the cold, oxygen rich water • farther downstream, plankton float in the warmer, calmer waters. • plants set roots in sediment • catfish and carp live in these calmer waters.

21. Rivers in Danger • Industries use river water in manufacturing processes, for waste disposal • used to dispose sewage and garbage. • polluted rivers with toxins, made river fish inedible. • runoff from the land puts pesticides, poisons into rivers and coats riverbeds with toxic sediments.