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Download Aquatic Ecosystems Section 1 Freshwater Ecosystems
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Aquatic Ecosystems Section 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. Aquatic Ecosystems Section 1 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. Aquatic Ecosystems Section 1 Characteristics of Aquatic Ecosystems • temperature, sunlight, oxygen, and nutrients determine organisms • organisms grouped by location and adaptations. Aquatic Ecosystems Section 1 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. Aquatic Ecosystems Section 1 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. Aquatic Ecosystems Section 1 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. Aquatic Ecosystems Section 1 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. Aquatic Ecosystems Section 1 Life in a Lake • in regions where lakes partially amphibians burrow into the littoral mud to avoid freezing Aquatic Ecosystems A Lake Ecosystem Section 1 Aquatic Ecosystems Section 1 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. Aquatic Ecosystems Section 1 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 Aquatic Ecosystems Section 1 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). Aquatic Ecosystems Freshwater Wetlands Section 1 Aquatic Ecosystems Section 1 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. Aquatic Ecosystems Section 1 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. Aquatic Ecosystems Section 1 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. Aquatic Ecosystems Section 1 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 Aquatic Ecosystems Section 1 Human Impact on Wetlands • previously considered wastelands, breeding grounds for insects. – many drained, filled, and cleared for development laws now protect many wetlands Aquatic Ecosystems Section 1 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 Aquatic Ecosystems Section 1 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. Aquatic Ecosystems Section 1 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.
