Freshwater Life Zones Melissa Eng, Martha Holland, Conner Martin, Colin Ng, and David Wright.
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Transcript of Freshwater Life Zones Melissa Eng, Martha Holland, Conner Martin, Colin Ng, and David Wright.
Freshwater Life Zones
Melissa Eng, Martha Holland,Conner Martin, Colin Ng, and
David Wright
Aquatic Environments
• Water covers 71% of the Earth's surface• Saltwater• Freshwater• Four Groups of organisms
o Planktono Nektono Benthoso Decomposers
• Euphotic Zone• Bottom of the Ocean
Climate
Lakes• Very low salt content• Largely varying temperature• Zonated, often with varying degrees of water clarity
Rivers• Often cooler temperatures, warming as the river nears the
ocean• Murky water, progessively more so as the river nears the
ocean• High oxygen content
Wetlands• Higher salt content• Wide variety of plant life
Plant Life
Why are there so many plants? • lots of carbon dioxide• sunlight and nutrients
What kinds of plants?• surface: duckweed• water column: floating strands of waterweed• water surface: water lilies • shallow water at edge: reed varieties
Limiting growth factors? • pressure• light intensity
Effects of Plant Nutrients on Lakes: Too Much of a Good Thing...Nutrients affect the types and numbers of organisms the lake can support• lakes are classified by:
nutrient content primary productivity
o oligotrophic: poorly nourished o eutrophic: well nourishedo mesotrophic: between these extremes
Cultural eutrophication: human inputs of nutrients from atmosphere and nearby urban/agricultural areas (accelerates eutrophication)
Animal Life
10,000 species of fish Less than 5,000 species of amphibians Few hundred types of reptiles/mammals/birds
o newts and salamanders, frogs and toads, turtles, crocodiless, snakes, birds, beavers/otters/hippopotamus/sea cows
Invertebrates: land-living but live in freshwater early on, adult freshwater stages, bottom-living community Vertebrates: fish!
40% of all fish species live in freshwater
Lakes: Water-filled Depressions
What are lakes?Large bodies of standing freshwater formed when precipitation, runoff, and groundwater seepage fill depressions in the earth's surface What causes these depressions? - glaciation - crustal displacement - volcanic activity Where do lakes get their water? - rainfall - melting snow - streams that drain surrounding watersheds
Freshwater Lakes: The Littoral ZoneThe littoral zone is the top layer near the shore• sunlight penetrates all the way to sediment • most productive zone• biodiversity: algae, rooted plants, animals
(turtles, frogs, crayfish), fish(bass, perch, carp)
Freshwater Lakes: The Limnetic ZoneThe limnetic zone is the surface layer away from shore that extends to depth penetrated by sun• photosynthetic body of the lake• organisms:
microscopic phytoplankton (floating microorganisms) and zooplankton
nekton (actively swimming animals) large fish
Freshwater Lakes: The Profundal ZoneThe profundal zone (also known as the euphotic zone) is the section of water too dark for photosynthesis• low oxygen levels• fish! • primary consumers
attached or at bottom of lakebenthos: bottom-dwelling animals
Freshwater Lakes: The Benthic ZoneThe benthic zone is the bottom of the lake • inhabitants: decomposers, detritus feeders, fish• nourished by dead matter from:
littoral and limnetic zones sediment
Lakes and the Seasons
What happens during summer and winter?• water stratified in different temperature layers• no mixing!
What happens during fall and spring?• overturns: all layers mix
temperature equalizes throughout oxygen: surface to bottom nutrients: bottom to surface
Littoral Zone
Limnetic Zone
Profundal Zone
Benthic Zone
Sunlight
Painted Turtle
Green Frog
Pond Snail
Diving Beetle
YellowPerch
Bloodworms Northern Pike
Plankton
Muskrat
Blue-winged Teal
Textbook Figure 6.15
Water travelling from mountains to the sea creates different aquatic conditions and habitats! Terms to know: • Surface water is precipitation that does not sink into the ground or
evaporate. When surface water flows into streams, it becomes runoff.
• A watershed (or drainage basin) is the land area that carries runoff, sediment, and dissolved substances to a stream.
Small streams form rivers; rivers travel downhill to the ocean. Streams shape the land and receive nutrients from bordering land ecosystems.
Freshwater Streams and Rivers; From the Mountains to the Oceans
http://www.eoearth.org/article/River
Freshwater Streams and Rivers...
The Source ZoneStreams often begin in mountainous or hilly areas at the source zone. Source zone headwaters typically:• are shallow, cold, clear, and swiftly flowing• dissolve large amounts of oxygen from the air (high DO content)• lack nutrients/phytoplankton; streams are not very productive
Most nutrients at the source zone come from the organic matter (leaves, branches, bodies of living and dead insects) that falls into streams. The zone is populated by cold water fish with compact, flattened bodies that allow them to live under stones; algae/mosses; organisms that require high levels of DO to survive
Freshwater Streams and Rivers...
The Transition ZoneHeadwater streams merge to form wider, deeper, and warmer streams at the transition zone. At the transition zone, water flows down gentler slopes with fewer obstacles. The transistion zone is characterized by water that:• is cloudier due to suspended sediment• slowelowing• contains less dissolved oxygen• is warmer in temperatuer, supporting producers - higher productivity
Freshwater Streams and Rivers...The Floodplain ZoneAt the floodplain zone, streams join into wider and deeper rivers that flow across broad, flat valleys. The floodplain zone is characterized by:• higher temperatures• less dissolved oxgen• slow moving water that supports a fairly large populations of
producers• increased erosion/run off• muddy water containing high oncentrations of silt
At the mouth, the river may divide into channels as it flows through deltas.
Freshwater Inland Wetlands: Vital Sponges• Marshes, swamps, bogs • Not considered to be freshwater ecosystems, due to
higher salt content• Support many terrestrial and aquatic species• Home to over one third of endangered species in the
United States• Most biologically productive ecosystems in the world• Act as a filter for poll
Case Study: Inland Wetland Losses in the United States• Causes of Wetland loss
o 80% caused by crop growth o Mining o Forestry o Oil and Gas extraction
• Other countries o Ex. German and France 80% loss
• 95% of wetlands are inland freshwater wetlando Alaska has many wetlands
• The loss of natrual capital
Impacts of Human Activities on Freshwater Systems• humans disrupt many freshwater systems
o through pollution of watershedso both irrigation and industrial byproducts can effect
freshwater farm land runoff waste from factories
o hydroelectricity or damso filling in wetlands
This is an example of a watershed
Current Event: India and Pakistan at Odds Over Shrinking Indus Riverhttp://news.nationalgeographic.com/news/2011/10/111012-india-pakistan-indus-river-water/ • India and Pakistan's major industries use billions of gallons of
water each year (on average, 737 billion gallons of water withdrawn from the Indus River annually to grow cotton)
• Irrigation and hydroelectric projects are draining the river's flow; glaciers are melting in Kashmir which will increase flooding and eventually drain the water supply
• Downstream provinces are drying out, coastal districts becoming "economically orphaned"
• Competition for water is provoking conflict between the two nations
• More conservation and adaptation is necessary!
To Do ListNote sheet for classAssessmentVideo clips/visual representations - everyone look for videos/photos to enhance slides! (give link to Baxley prior to class) students.discovery.education.com Code: GHS2010 Password: researchCurrent Event for discussionAll slides: Martha - freshwater streams/rivers, current event Melissa - lakes, effects of plant nutrients Colin - impacts of human activities, aquatic environment Connor - freshwater inland wetlands, freshwater systems David - case study
Works Consulted
Day, Trevor. Lakes and Rivers. New York: Chelsea House, 2006. Print.
Hicks, Sarah. "Pollution." Lake Scientist. Web. 19 Oct. 2011.<http://www.lakescientist.com/learn-about-lakes/water-quality/pollution.html>. "Humans and the Water Cycle | Sciencelearn Hub." Home | Sciencelearn Hub. Web. 18 Oct. 2011. <http://www.sciencelearn.org.nz/Contexts/H2O-On-the-Go/Science-Ideas-and-Concepts/Humans-and-the-water-cycle>. Ruzycki, Elaine, and Lindsay Anderson. "Lake Ecology -- Lake Zones." Lake Access: Real Time and Historical Water Quality Data for Lake Users. Natural Resources Research Institute. Web. 19 Oct. 2011. <http://www.lakeaccess.org/ecology/lakeecologyprim9.html>. Smith, David K. "The Freshwater Biome." University of California Museum of Paleontology. California Academy of Sciences, 2005. Web. 19 Oct. 2011. <http://www.ucmp.berkeley.edu/exhibits/biomes/freshwater.php>.