Freshwater Biomes

Chapter 10

Objectives Describe the factors that characterize the various

types of aquatic biomes.

10.1 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 RateLet’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 waterSaltwater FreshwaterAll 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 pptFresh water: 0.5 pptBrackish 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 pptDensity 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

Littoralzone Limnetic

zone

Photiczone

PelagiczoneBenthic

zone Aphoticzone

(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

typesFlowing-water ecosystemsStanding-water ecosystems

Lakes, ponds also wetlands, bogs, swamps, marshesNet flow is little, but water circulates, distributing warmth,

oxygen and nutrients

Types of Standing-Water EcosystemsAbiotic Factors Biotic Factors

Lake Deepest type of standing water; may have an aphotic zone; may be fed by underground aquifer

Main producers are floating algae in the photic zone and benthic plants along the shoreline, complex food webs

Pond Light reaches the benthic zone; fed mostly by rainfall; may be seasonal

Main producers are plants and algae that grow on the bottom; food web usually simpler than in lakes

Marsh Very shallow water with land occasionally exposed; soil is saturated; water often lacks oxygen, may be freshwater, saltwater or brackish; often tidal, Florida everglades largest in US

Plants have roots under water, but leaves are above the water; mostly grasses, cattails and rushes; ducks, waterfowl and benthic animals are common

Types of Standing-Water EcosystemsAbiotic Factors Biotic Factors

Swamp Land is soaked with water because of poor drainage; usually along low streambeds and flat land; mangrove swamps are salty and found along coastlines

Dominated by large trees and shrubs, plants are adapted to grow in muddy, oxygen-poor soil; cypress trees common in the south, willow and dogwood common in N US

Bog Inland wetland with little inflow or outflow; soil is acidic; decay is slow; carbon is stored in dead plants

Sphagum moss is the dominant organism; partly decayed moss accumulates as peat

Standing Water Organisms Standing-water ecosystems have several

levels of habitatOrganisms that live in the upper levels are

different than those in the middle and bottom layers

Top level supports the plankton communityPlankton are Microorganisms that drift in the water

About the size of dustSmall fish feed on plankton and insectsLarger fish feed on the smaller fish so they

are important to the food web

Standing Water Organisms Two types of plankton

PhytoplanktonCarries out photosynthesisThe main producers in aquatic biomes

ZooplanktonDo not carry out photosynthesisConsumers of phytoplankton

Lake

Question

Which is it?

A. Lake

B. Pond

C. Swamp

D. Bog

Pond

Question

Which is it?

A. Lake

B. Pond

C. Swamp

D. Bog

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 importantAct as filters, detoxifying chemicals in the

waterCan be used as part of treatment systems for

waste water Important for breeding, feeding & resting

grounds for migratory waterfowlFlood protection along banks of riversRefilling of aquifers

Wetlands Are being destroyed by human activity at an

alarming rateNot as attractive as other natural habitatsBreeding grounds for mosquitoesUnpleasant odor – swamp gas – methaneThe land is often near coastal areas so it’s very valuable

for other uses (resorts, motels, etc)Used as landfill sitesCities built on filled wetlandsBill Nye

Marsh

Question

Which is it?

A. Swamp

B. Marsh

C. Mangrove

D. Bog

SwampQuestion

Which is it?

A. Swamp

B. Marsh

C. Mangrove

D. Bog

Mangrove Swamp

Question

Which is it?

A. Swamp

B. Marsh

C. Mangrove

D. Bog

The Bog

Question

Which is it?

A. Swamp

B. Marsh

C. Mangrove

D. 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 landMost people associate these names with different sized

bodies of water, however, scientists call all above ground bodies of flowing freshwater streams

Recall that fresh water can also flow underwater through aquifersEven though underground, they contain fish and other

animals

Stream Organisms

Stream organisms are adapted to the rate of the waters movementPlants have roots that keep them in placeSome organisms burrow into sandy bottomsSome have hooks to grab hold of plantsSome have suckers to anchor to rocksSome have ability to swim upstreamSeek calm pools at sides of streams

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.

Mayfly - As adults, mayflies live only a few hours or days, living only long enough to mate and lay eggs.

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 headwaterMountain 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 slowAs 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.

Sediments accumulate 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