FRESHWATER BIOMES Ecology Chapter 10

Aquatic Biomes Water covers more than 70% of the Earth’s surface Aquatic habitat: one in which organisms live in or on water not grouped geographically difficult to show on a map often determined by depth rather than location

Land vs. Aquatic Biome Temperature and rainfall are important factors when distinguishing one land biome from another. Temperature in large bodies of water are relatively stable. Rainfall has less effect on aquatic biomes because organisms are already underwater.

Important Factors Salinity: The amount of dissolved salts in a sample of water. Measured in parts per thousand (# units of salt in a thousand units of water) Aquatic biomes can be divided into two main groups Saltwater (30 parts/1000) Freshwater (0.5 parts/1000) Brackish water > saline than fresh, < saline than ocean water

Important Factors Depth – directly related to the amount of sunlight that reaches the bottom of the body of water. Sunlight determines the types and amounts of plants that can grow. (Remember – plants are producers, and the base of the food web)

Photic zone: top layer of sunlight that receives enough sunlight for photosynthesis to occur. Aphotic zone: below the photic zone. Sunlight does not reach this zone. Benthic zone: the floor of a body of water

Question Break What characteristic distinguishes the photic zone from the aphotic zone? Sunlight How is salinity measured? Parts per thousand (# units salt/1000 units of water)

Standing-water Ecosystems The most common types of standing-water ecosystems are lakes and ponds. Also includes wetlands (bogs, swamps, etc.) While there is no flow of water in and out of most standing-water ecosystems, there is a circulation of water throughout the system. Review question: How does this circulation occur? What causes the circulation?

Types of Standing-Water Ecosystems Abiotic Factors Biotic Factors Deepest type of standing water; may have an aphotic zone; may be fed by aquifers Floating algae in the photic zone, plants along shoreline, complex food webs Light reaches benthic zone; fed by rainfall – may be seasonal Main producers – plants and algae that grow on bottom; food web simpler than lakes Plants have roots under water, leaves above water; grasses, cattails; ducks and waterfowl Very shallow water, land occasion- ally exposed; saturated soil; Florida Everglades largest freshwater marsh Land soaked due to poor drainage; usually along low streambeds and flat land Large trees and shrubs; cypress trees in south, willow and dogwood in north Inland wetland; soil is acidic; decay is slow Sphagnum moss dominant organ- ism, partly decayed moss accumu- lates as peat Lake Pond Marsh Swamp Bog Types of Standing-Water Ecosystems

Standing-Water Organisms Several levels of habitat Plankton community Plankton: microorganisms that float on the surface of the water Phytoplankton: carry out photosynthesis. Main producers in most aquatic biomes Zooplankton: do not carry out photosynthesis. Include microscopic animals and protozoans. Consumers – feed on phytoplankton Big fish feed on little fish, little fish feed on plankton Benthic community Scavengers, depend upon a steady rain of organic material that drifts down from the top. Decomposers are also part of this community

Wetlands Ecosystems in which the roots of plants are submerged under water at least part of the year. Soils are soaked with water, and very low in dissolved oxygen. Marshes, swamps, bogs Act as filters, detoxifying chemicals that passes through them Can be used as part of a treatment system for waste water Important breeding, feeding, and resting grounds for waterfowl.

Endangered Wetlands Wetlands are being destroyed by human activity. Many do not find wetlands as attractive as other natural habitats Land (especially in coastal areas) is developed for resorts and homes Swamp Lands Act of 1849 encouraged the filling and draining of wetlands

Florida Everglades Once a swampy marsh that covered 160 km from Lake Okeechobee to the tip of Florida. Region has a wet season from May to October, followed by a dry season. Natural fires occur during the dry season, burning off dried plant material. Home to a large number of organisms, that are adapted to the annual cycle of growth, drought, and fire.

In 1983, “Save Our Everglades” campaign was launched. 100,000 acres returned to wetland Flow of water adjusted to provide a more natural water supply

Flowing-Water Ecosystems Rivers, streams, creeks, brooks All water that flows over land - to a scientist they are all streams Water that flows underground is an aquifer Stream Organisms Adapted to the rate of the water’s movement Hooks to grab hold of plants Suckers that anchor to rocks

Stream Stages Youthful Old ________: _______: Rapids Waterfalls Fast-moving water Steep slope _______: Broad floodplain Meanders Oxbow lakes Meander Scars

Important Definitions River System ____________ – a stream and all its tributaries ________ – a smaller stream that empties into a larger stream _________ – the land area drained by a river system ______ – a high point that separates river systems Tributary Watershed Divide

________ – the bends and curves of a stream Meanders ________ – the bends and curves of a stream

Oxbow lake deposition erosion

____________ – deposit formed when a stream spreads out onto a less steep area Alluvial Fan

_____ – where a stream empties into a larger body of water Delta _____ – where a stream empties into a larger body of water

Ganges River Delta

Nile River Delta

Human Impact on Streams Flow and course of streams has been changed by human activities Dams create reservoirs and are used for hydroelectric plants Dams and levees can be used to irrigate farmland Dams and levees affect farmland by preventing sediments from being deposited on floodplains Change of course damages or destroys the habitats of organisms Areas that were once streambeds become the bottoms of deep lakes

Chapter 10 Review To be considered fresh water, water must contain salt in a concentration More than 30 parts per thousand Less than 0.5 parts per million More than 40 parts per million Less than 0.5 parts per thousand

Brackish water is common in Lakes Oceans Coastal marshes aquifers

Sunlight reaches the benthic zone in Ponds Deep lakes Oceans Vents in the ocean floor

Organisms that live in the benthic zone of deep lakes are often Producers Plants Scavengers plankton

A type of standing-water habitat in which the soil is acidic and decay is slow is called a Bog Swamp Marsh pond

Phytoplankton are Consumers Decomposers Producers scavengers

Wetlands are Easy to define Have traditionally been protected by laws Are nonproductive areas that could be better used for other purposes Are important breeding grounds

Sediments tend to accumulate In slow-moving parts of a stream On the outer edge of a curve in a stream In fast-moving parts of a stream Near the beginning of the stream

Streams always flow South Toward the ocean Downhill Toward the poles of Earth

Levees and dams are beneficial to farmlands because they Prevent stream sediments from being deposited on the fields Protect the fields from floods Provide a source of irrigation Help refill aquifers

Levees and dams are harmful to farm lands because they Prevent stream sediments from being deposited on the fields Protect the fields from floods Provide a source of irrigation Help refill aquifers