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.

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.

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

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.

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.

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.

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.

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

A Lake Ecosystem

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.

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

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).

Freshwater Wetlands

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.

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.

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.

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

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

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

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.

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.