Freshwater Biomes

Freshwater Biomes Chapter 10

10.1 Aquatic Biomes Objectives • Describe the factors that characterize the various types of aquatic biomes.

Aquatic Biomes • What type of biomes have we learned about so far? • Rainforest, savannah, desert, decidious forest, etc. • These are all terrestrial biomes meaning they are land biomes. • But, land only covers about 30% of the earth’s surface • So it’s not surprising that many of Earth’s organisms live in aquatic habitats • Aquatic habitat is one in which the organisms live in or on water

If all the world's water were to form a single drop, this is how big it would be: A sphere stretching from Salt Lake City, Utah to Topeka, Kansas. Though this mega-droplet looks small compared to Earth's bulk, the two dimensionality of this image is somewhat deceiving. In fact, the water sphere would have a diameter of about 860 miles and a volume of about 332,500,000 cubic miles. http://ga.water.usgs.gov/edu/2010/gallery/global-water-volume.html

Aquatic Habitats • Aquatic habitats are not grouped the same way as terrestrial biomes. What features are used to classify terrestrial biomes? • Temperature and rainfall • Temperature in large bodies of water is more stable than on land, and rainfall does not affect aquatic creatures because they are already underwater • Aquatic Biome Characteristics are determined by: • Salinity • Depth • Dissolved Oxygen • Flow Rate Let’s look at each of these factors!

Salinity • Aquatic biomes can be divided into two main groups, based on the amount of dissolved minerals in the water • Saltwater • Freshwater • All bodies of water contain some dissolved salts and minerals, but ocean water has a lot more than lakes, ponds or streams • The amount of dissolved salts in a sample of water is called salinity

Salinity • Salinity is measured in parts per thousand, the number of units of salt in a thousand units of water • ocean water: 30 ppt • Fresh water: 0.5 ppt • Brackish water: in between • Brackish water is more saline than fresh water, but less saline than ocean water and is usally found where fresh water meets the ocean • Great Salt Lake (hypersaline): 40 ppt • Density demo

Depth • The ecosystem found in a body of water is greatly influenced by the amount of sunlight that penetrates to the bottom. • Amount of sunlight is key in determining the type and amount of plants that can grow • Since plants provide the food for animals, depth determines the amount and types of animals • Video

Depth Zones • Photic Zone • The top layer of water that receives enough sunlight for photosynthesis • Up to 200 m depending on how cloudy the water is • Aphotic Zone • Sunlight never reaches • Very deep lakes and the oceans • Benthic Zone • The floor of a body of water • May have plants and animals depending on depth

Fig. 52-16a Littoral zone Limnetic zone Photic zone Pelagic zone Benthic zone Aphotic zone (a) Zonation in a lake

10.2 Standing-Water Ecosystems Objectives • Identify the characteristics of different types of standing-water ecosystems • Explain the value of wetlands and the reason for their decline

Standing-water ecosystems • Freshwater biomes can be divided into 2 main types • Flowing-water ecosystems • Standing-water ecosystems • Lakes, ponds also wetlands, bogs, swamps, marshes • Net flow is little, but water circulates, distributing warmth, oxygen and nutrients

Types of Standing-Water Ecosystems

Standing Water Organisms • Standing-water ecosystems have several levels of habitat • Organisms that live in the upper levels are different than those in the middle and bottom layers • Top level supports the plankton community • Plankton are Microorganisms that drift in the water • About the size of dust • Small fish feed on plankton and insects • Larger fish feed on the smaller fish so they are important to the food web

Standing Water Organisms • Two types of plankton • Phytoplankton • Carries out photosynthesis • The main producers in aquatic biomes • Zooplankton • Do not carry out photosynthesis • Consumers of phytoplankton

Question • Which is it? • Lake • Pond • Swamp • Bog Lake

Question • Which is it? • Lake • Pond • Swamp • Bog Pond

Wetlands • Wetlands are ecosystems in which the roots of plants are submerged under water at least part of the year • Marshes • Swamps • Bogs • Soil is soaked in water • Very low in dissolved oxygen • Wetlands

Wetlands continued • Very important • Act as filters, detoxifying chemicals in the water • Can be used as part of treatment systems for waste water • Important for breeding, feeding & resting grounds for migratory waterfowl • Flood protection along banks of rivers • Refilling of aquifers

Wetlands • Are being destroyed by human activity at an alarming rate • Not as attractive as other natural habitats • Breeding grounds for mosquitoes • Unpleasant odor – swamp gas – methane • The land is often near coastal areas so it’s very valuable for other uses (resorts, motels, etc) • Used as landfill sites • Cities built on filled wetlands • Bill Nye

Question • Which is it? • Swamp • Marsh • Mangrove • Bog Marsh

Swamp • Question • Which is it? • Swamp • Marsh • Mangrove • Bog

Mangrove Swamp • Question • Which is it? • Swamp • Marsh • Mangrove • Bog

The Bog • Question • Which is it? • Swamp • Marsh • Mangrove • Bog

Florida Everglades • Much was drained to create farmland. • The natural cycle was destroyed and populations of many organisms was greatly reduced • Some land has been returned to wetlands and the water flow has been adjusted • Still an endangered habitat but now there is hope

10.3 Flowing Water Ecosystems Objective • Describe how abiotic factors of gravity, erosion, and sedimentation affect stream ecosystems

Flowing-water ecosystems • Flowing water ecosystems have many different names; rivers, streams, creeks, and brooks • these all refer to water that flows over land • Most people associate these names with different sized bodies of water, however, scientists call all aboveground bodies of flowing freshwater streams • Recall that fresh water can also flow underwater through aquifers • Even though underground, they contain fish and other animals

Stream Organisms • Stream organisms are adapted to the rate of the waters movement • Plants have roots that keep them in place • Some organisms burrow into sandy bottoms • Some have hooks to grab hold of plants • Some have suckers to anchor to rocks • Some have ability to swimupstream • Seek calm pools at sides of streams Mayfly - As adults, mayflies live only a few hours or days, living only long enough to mate and lay eggs. The nymphs live under water up to two years, move to land, and shed as adults. The legs have a single claw and there may be two to three tails.

Stream Flow • Often begin from runoff from melting snow • Flow downhill • Flow towards the oceans • At source flow is too fast for most organisms • Water near the source is called headwater • Mountain headwaters are cold and contain large amounts of dissolved oxygen that can support a variety of organisms, but the water flows too rapidly

Stream Flow • As the slope of the land becomes more gentle, streams slow • As stream slows, small particles settle to bottom called sediments. • Sediments provide a place for plants to grow • Plant growth slows water flow, allowing water to be warmed by the sun • Phytoplankton multiply in the warmer water providing food to support consumers

The Course of a Stream • Sedimentation and erosion cause the course to change • Results in a winding or meandering of the stream • As the stream curves, the water flowing along side the streams slows and the water outside speeds up. • Sedimentsaccumulate on the inner edge because of slowed flow • Increased erosion occurs along the banks of the stream cause it to become more curved

Human Activity • Streams changed dramatically by human activity • Streams dammed to create reservoirs • Stream beds become lake bottoms • Levees for flood control • Dredging for shipping • Changing the course of a stream damages or destroys the delicate habitats of many organisms • Stops natural flooding which is a natural and beneficial part of the ecosystem.

The End

Freshwater Biomes