Freshwater Biome Ch.10
Aquatic Biomes • Water covers ~ 70% of Earth • Aquatic habitat: organisms live in or on water • Grouped by depth and salinity of water • Rainfall and temp. categorize land biomes, but temp. of waters is fairly consistent and rainfall does not affect the organisms Campcrescent.com
Salinity • Salinity: amount of dissolved salts in the water • Saltwater: 30 parts/thousand • Oceans and some lakes (Great Salt Lake in Utah) • Many saltwater lakes are 40 parts/thousand…..why? • Freshwater: 0.5 parts/thousand • Most lakes, ponds, and rivers
Salinity • Hydrometer • measures density of water by testing buoyancy • Buoyancy • amount of mass that can float on the water • Increase in salt inc. in density inc. in buoyancy http://spot.pcc.edu/~lkidoguc/Aquatics/AqEx/Water_Buoyancy.htm
Depth • Ecosystem depends on amount of sunlight that reaches the bottom • More sunlight results in a greater number of plants • Plants-basis of food web • More plants leads to more animals
Depth zones • Plants only grow in photic and shallow parts of benthic zone • Benthic animals: insect larvae, snails, catfish, turtles • Alvin, the research submarine, studied cracks in the ocean floor • Base of the food web down there was bacteria • Bacteria use energy from chemicals that ooze through those cracks
Questions • 1. H0w is salinity determined and measured? • 2. Suppose a friend wants to set up an aquarium and discovers that saltwater fish are more attractive, but a freshwater tank is easier to maintain. Your friend decides to set up a freshwater aquarium but buys some saltwater fish to place in it. Predict what the result of this decision would be, and why?
2 types of freshwater biomes • Standing water • Ponds, lakes, marsh, swamps • Flowing water http://rrms-biomes.tripod.com/id10.html
Standing water organisms • Top level • Plankton • Organisms that drift in water • About size of a dust particle • Phytoplankton: carries out photosynthesis • Main producers in aquatic biomes • Zooplankton: don’t carry out photosynthesis • Consumers: feed on phytoplankton • Benthic Zone • Home to scavengers • Feed on remains of other organisms
Wetlands • Roots of plants are submerged under water at least part of the year • Examples: marshes, swamps, bogs • Soil is soaked with water and contains little dissolved oxygen • Important in biosphere • Filter chemicals in water • Migratory fowl breed, feed, and rest there • Water sweeps into and refills aquifers • Protection against floods
Wetlands • Common grass is papyrus • Egyptians first used to make paper around 3000 bc • Most common writing surface in eastern Mediterranean for over 4000 years
Wetlands-human impact • More than half the wetlands in the U.S. have been destroyed • Not attractive • Give off unpleasant odor (methane from bacteria) • Breeding ground for mosquitoes • Usually on coast so can be ideal for development companies • Large so are used at times as landfills • Clean water act: prohibits the filling of wetlands • In US only 8% wetlands are federally protected
Florida Everglades • Home to a large number of organisms • Adapted to cycles of growth, drought, and fire • Water was drained from the everglades to create farmland • 1947: Everglades National Park • Created to save everglades, but needed water • 1967 a canal was dug to get water to park • Water came too fast in too narrow of a stream • Caused flooding of the area and organisms homes • 93% decrease of bird population and decline of alligators • 1983: Save our Everglades campaign • Designed to clean up contamination from farms and restore a natural water flow100,000 acres of wetland has been restored
Questions • 1. What is the difference between the role of phytoplankton and that of zooplankton? • 2. The number of migratory birds in the tundra during the summer has been declining. How might changes that have taken place in the wetlands have contributed to this decline?
Flowing Water • Rivers, streams, creeks, brooks • Scientists refer to all above ground bodies of water as Streams.
Flowing Water Organisms • Organisms that live in flowing water habitats are adapted to the rate of water movement. • Adaptations: • Hooks (grab plants) • Suckers (attach/anchor to rocks) • Salmon and trout are well adapted to flowing water • Grow in freshwater but spend adult life in ocean • Breeding season they swim upstream to same spot they hatched • Find the “spot” by smelling the small amt of chemicals in H2O
Flow • Most streams begin at high altitude • From runoff of melting snow • Gravity brings downhill • Starts Inland usually then goes out to ocean • Where streams slow down is where a majority of sediment accumulates • Sediment provides a place for plant roots to grow • Colder water contains more dissolved oxygen and therefore supports more animal life • Why pop loses its fizz when room temperature
Flow • Erosion along the fast-flowing outer edge and sedimentation along the slow-flowing inner edge result in the winding, or meandering, of a stream • The older a stream is the more curvy it gets • Human activity • Streams have been dammed to make resevoirs • Dams, dikes, and irrigation canals used to change stream courses • Dams also used to control flooding
Questions • 1. Why are there fewer organisms in the headwater of a stream than further downstream? • 2. the headwaters of a stream often contain more dissolved oxygen than the water hundreds of kilometers downstream. Why is this true?