1. Objectives
Describe the factors that determine where an organism lives in an aquatic ecosystem.
Describe the littoral zone and the benthic zone that make up a lake or pond.
Describe two environmental functions of wetlands.
Describe one 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.