Aquatic Ecosystems Chapter 7

Water Biomes Types of organisms present depends on salinity Divided into freshwater and marine Freshwater includes lakes, ponds, rivers, streams, and wetlands Marine ecosystems include marshes, swamps, coral reefs, and oceans

Characteristics of Aquatic Ecosystems Temperature, sunlight, oxygen, and nutrients determine which organisms live in the water Organisms are divided into three broad categories depending on their location and adaptations These categories are plankton, nekton, and benthos.

Plankton Organisms that cannot swim against currents Drifting plants, called phytoplankton, are the base for most aquatic ecosystems Most are microscopic Drifting animals are called zooplankton

Nekton Free swimming organisms like turtles, fish, and whales

Benthos Bottom dwelling organisms such as mussels, worms, and barnacles Many attach to hard surfaces

Lakes and Ponds Lakes and ponds form naturally where groundwater reaches Earth's surface Humans and other animals can also create them Lakes and ponds are structured into vertical and horizontal zones

Littoral Zone A nutrient rich zone near the shore Rooted plants, such as cattails and pond lilies, live near the shore Phytoplankton make their own food using photosynthesis

Benthic Zone Some areas are too deep for photosynthesis Decomposes live on dead plants and animals that drift down from the top Fish adapted to cooler water live here too

How Nutrients Affect Lakes Eutrophication is an increase in the amount of nutrients in an aquatic ecosystem This also causes an increase in the amount of bacteria This eventually reduces the amount of available oxygen which begins to kill fish and other oxygen loving organisms Runoff accelerates eutrophication

Freshwater Wetlands Areas of land covered with freshwater for at least part of the year Mainly swamps and marshes Marshes contain non-woody plants Swamps contain woody plants Wetlands act as filters or sponges by absorbing and removing pollutants Wetlands help control flooding

Environmental Functions of Wetlands Trapping and filtering sediments, nutrients, and pollutants Reducing the likelihood of floods Buffering shorelines against erosion Providing spawning grounds and habitat for fish and shellfish Providing habitat for rare, threatened, and endangered species Providing recreational areas

Marshes Most freshwater wetlands sin the US are in the southeast The Florida Everglades is the largest Most occur on low, flat land and have little water Salinity in marshes varies

Swamps Occur on flat, poorly drained land, often near streams Plant species depend on level of salinity Freshwater swamps are ideal for amphibians

Human Impact on Wetlands Wetlands used to be viewed as wastelands and breeding grounds for insects Many have been drained, filled, and cleared for farming and housing The Everglades used to cover over 8 million acres, now it barely covers 2 million acres Laws now prevent the destruction of many wetlands

Rivers Many rivers originate from snow melt in the mountains Headwaters (beginning of the river) water is usually cold and runs swiftly As it flows down the mountain, it becomes wider and warmer Runoff washes into the river affecting its health

Copy now, answer later List two factors that determine where an organism lives in an aquatic ecosystem. Compare the littoral zone with the benthic zone of a lake. List two environmental functions that wetlands provide. How do these functions affect you? Describe one threat against river ecosystems. Write a short paragraph that explains how fertilizing your yard and applying pesticides can affect the health of a river ecosystem.