© Cengage Learning 2015 Freshwater ecosystems –Provide major ecosystem and economic services –Are irreplaceable reservoirs of biodiversity 8-4 Why Are Freshwater Ecosystems Important?

© Cengage Learning 2015 Fig. 8-14, p. 178 Natural Capital Freshwater Systems Ecological Services Economic Services Climate moderation Food Nutrient cycling Drinking water Waste treatment Irrigation water Flood control Groundwater recharge Hydroelectricity Habitats for many species Transportation corridors Genetic resources and biodiversity Recreation Scientific information Employment

© Cengage Learning 2015 Freshwater life zones include: Standing (lentic) bodies of freshwater –Lakes –Ponds –Inland wetlands Flowing (lotic) systems of freshwater –Streams –Rivers Water Stands in Some Freshwater Systems and Flows in Others

© Cengage Learning 2015 Lakes – large bodies of standing freshwater formed when precipitation, runoff, streams, rivers, and groundwater seepage fill depressions in the earth’s surface. Water Stands in Some Freshwater Systems and Flows in Others (cont’d.)

© Cengage Learning 2015 Depressions (basins) may be the result of: -- Glaciation -- Displacement of the earth’s crust -- Volcanic activity Water Stands in Some Freshwater Systems and Flows in Others Crater Lake, Oregon

© Cengage Learning 2015 Depressions (basins) may be the result of: Additional Info Many lakes, especially those in the Northern Hemisphere, were formed by glaciers that covered large areas of land, about 18,000 years ago. The huge masses of ice carved out great pits and scrubbed the land as they moved slowly along. When the glaciers melted, water filled those depressions, forming lakes. Lake Louise in Alberta, Canada Many lakes in US including the Great Lakes Some lake basins form where plate tectonics changed the Earth’s crust, making it buckle and fold or break apart. When the crust breaks, deep cracks, called faults, may form. These faults make natural basins that may fill with water from rainfall or from streams flowing in the basin. The Caspian Sea and Lake Baikal After a volcano becomes inactive, or when the top is blown off or collapses during an eruption, its crater may fill with rain or melted snow becoming a lake. Crater Lake, in the U.S. state of Oregon, one of the deepest lakes in the world Glaciation Displacement of the earth’s crust Volcanic activity Lake Baikal is one of the most biodiverse lakes on the planet with 1,340 species of animal and 570 species of plant – nearly half of which are endemic to the lake ecology.

© Cengage Learning 2015 Deep lakes have four zones based on depth and distance from shore: –Littoral zone –Limnetic zone –Profundal zone –Benthic zone Freshwater lakes vary in size, depth, and nutrient content

Fig. 8-16, p. 179 Painted turtle Blue-winged teal Green frog Muskrat Pond snail Littoral zone Plankton Diving beetle Northern pike Yellow perch Bloodworms Littoral zone -- Near shore and top sunlit layer where rooted plants grow -- High biodiversity (because ample sunlight and input of nutrients from surrounding land) -- Rooted plants, turtles, frogs, crayfish, and smaller fish

Fig. 8-16, p. 179 Painted turtle Blue-winged teal Green frog Muskrat Pond snail Littoral zone Plankton Diving beetle Northern pike Yellow perch Bloodworms O2O2 Temp?

Fig. 8-16, p. 179 Painted turtle Blue-winged teal Green frog Muskrat Pond snail Littoral zone Plankton Diving beetle Northern pike Yellow perch Bloodworms Limnetic zone -- Open, sunlit surface area away from shore -- Main photosynthetic zone (Produces food and oxygen to support most of the lake’s consumers) -- Phytoplankton, zooplankton, and larger fish (visit the littoral zone to feed and reproduce) Temperature decreases Oxygen conc decreases

Fig. 8-16, p. 179 Painted turtle Blue-winged teal Green frog Muskrat Pond snail Littoral zone Plankton Diving beetle Northern pike Yellow perch Bloodworms Profundal zone - Deep open water too dark for photosynthesis - Low oxygen levels and colder temps - Some fish

Fig. 8-16, p. 179 Painted turtle Blue-winged teal Green frog Muskrat Pond snail Littoral zone Plankton Diving beetle Northern pike Yellow perch Bloodworms Benthic zone -- Dark, cold bottom layer -- Decomposers, detritus feeders (insect larvae, mussels/clams, snails, crustaceans), some species fish (catfish, carp) -- Nourished primarily by dead matter

© Cengage Learning 2015 Lakes are classified according to their nutrient content: Oligotrophic lakes Mesotrophic lakes Eutrophic lakes Cultural eutrophication Some Lakes Have More Nutrients Than Others

© Cengage Learning 2015 Oligotrophic lakes –Deep lake with steep banks –Low levels of nutrients and low NPP –Very clear water –Small populations of plankton and fish Some Lakes Have More Nutrients Than Others Lake Tahoe, CA

© Cengage Learning 2015 Mesotrophic lakes - Most lakes fall midway between the two extremes Some Lakes Have More Nutrients Than Others

© Cengage Learning 2015 Eutrophic lakes (Over time, sediment, organic material, and inorganic nutrients wash into most oligotrophic lakes, and plants grow and decompose to form bottom sediments) –High levels of nutrients and high NPP –Typically shallow –Have murky water with high turbidity Some Lakes Have More Nutrients Than Others

© Cengage Learning 2015 Oligotrophy to Eutrophy Oligotrophy to Eutrophy TIME …. allows sediments to enter an oligotrophic lake. Plants will grow and decompose allowing for “natural eutrophication” to occur.

© Cengage Learning 2015 Cultural eutrophication of lakes from human input of nutrients Some Lakes Have More Nutrients Than Others

© Cengage Learning 2015 The Caspian Sea, in Europe and Asia, is the world’s largest lake. Salinity: Freshwater 0.5 ppt; Caspian Sea 12.8 ppt; Seawater 35 ppt; Dead sea 300 ppt Lakes vary in size. The largest freshwater lake is Lake Baikal by volume, or Lake Superior by area.

© Cengage Learning 2015 Lake Baikal (in Russia) is the world’s deepest lake. Its bottom is nearly 2 kilometers (more than 1 mile) deep. Lakes vary greatly in depth

© Cengage Learning 2015 Lakes vary greatly in elevation The lowest lake is the Dead Sea; It is more than 395 meters (1,300 feet) below sea level. One of the highest is Lake Titicaca, in the Andes Mountains; It is about 3,810 meters (12,500 feet) above sea level.

© Cengage Learning 2015 The Dead Sea is the deepest and one of the saltiest lake, ( ppt); 1000 ft. The Great Salt Lake, in the U.S. state of Utah, is the largest saline lake in North America. Its water is saltier than the ocean ( ppt). Lakes with high salinity

© Cengage Learning 2015 Millions of jellyfish float around in Jellyfish Lake in Palau’s Rock Islands. Moon jellies and golden jellyfish thrive without predators in this incredible freshwater lake, and they’re harmless to divers. Lake with the oddest inhabitant!

© Cengage Learning 2015 Surface water – Precipitation that does not sink into ground or evaporate Runoff – surface water that flows into streams Watershed or drainage basin – land area that delivers runoff, sediment, and dissolved substances to a stream. Freshwater Streams and Rivers Carry Large Volumes of Water

© Cengage Learning 2015Watershed

Mississippi River Basin

© Cengage Learning 2015 Streams – join to form rivers Rivers – flow downhill to the ocean Streams begin in mountainous or hilly areas, which collect and release precipitation or melted snow. The downward flow of surface water and groundwater from mountain highlands to the sea typically takes place in three aquatic life zones characterized by different environmental conditions: Source zone Transition zone Floodplain zone Freshwater Streams and Rivers Carry Large Volumes of Water

© Cengage Learning 2015 Source zone Consists of highland streams Shallow, cold, clear, swiftly flowing High dissolved oxygen; low nutrients Freshwater Streams and Rivers Carry Large Volumes of Water

© Cengage Learning 2015 Source zone Nutrients come from organic matter (leaves and bodies of insects) that falls in from nearby land. Trout found here; need a lot of oxygen. Freshwater Streams and Rivers Carry Large Volumes of Water

© Cengage Learning 2015 Transition zone Wider, deeper, warmer, slower flowing streams Freshwater Streams and Rivers Carry Large Volumes of Water

© Cengage Learning 2015 Transition zone More turbid (from suspended sediment) Less dissolved oxygen Has more producers Supports more fish (like bass) Freshwater Streams and Rivers Carry Large Volumes of Water

© Cengage Learning 2015 Floodplain zone Moving water has leveled mountains and craved canyons, and the rock and soil removed by water has been deposited as sediment in low-lying areas called floodplains. Freshwater Streams and Rivers Carry Large Volumes of Water

© Cengage Learning 2015 Floodplain zone Wide, deep rivers Broad, flat valleys Freshwater Streams and Rivers Carry Large Volumes of Water

© Cengage Learning 2015 Floodplain zone Higher temps and less dissolved oxygen Large populations of algae, cyanobacteria and rooted plants along banks Many fish Freshwater Streams and Rivers Carry Large Volumes of Water

© Cengage Learning 2015 Delta An area at the mouth of a river that was built up by deposited sediments and contains coastal wetlands and estuaries. Freshwater Streams and Rivers Carry Large Volumes of Water

Transition Zone Tributary Flood plain Oxbow lake Salt marsh Delta Deposited sediment Ocean Water Sediment Floodplain Zone Stepped Art Fig. 8-18, p. 180 Waterfall Lake Glacier Rain and snow Rapids Source Zone

© Cengage Learning 2015 Coastal deltas, mangrove forests, and coastal wetlands provide natural protection against storms Dams and levees reduce sediments in deltas –Subsidence of New Orleans Rising sea levels will inundate coastal areas Case Study: River Deltas and Coastal Wetlands

Fig. 8-19, p. 182

Fig. 8-20, p. 182

© Cengage Learning 2015 Inland wetlands –Lands located away from coasts that are covered with freshwater all or part of the time Include: Marshes (contain grasses and sedge) Swamps (contain trees) Prairie potholes (depression craved by glaciers) Floodplains Arctic tundra Freshwater Inland Wetlands Are Vital Sponges

© Cengage Learning 2015 Inland wetlands -- have great biodiversity; HPP Freshwater Inland Wetlands Are Vital Sponges

© Cengage Learning 2015 Provide free ecosystem and economic services –Filter and degrade toxic wastes –Reduce flooding and erosion –Help to replenish streams and recharge groundwater aquifers –Biodiversity –Food and timber –Recreation areas Freshwater Inland Wetlands Are Vital Sponges (cont’d.)

© Cengage Learning 2015 Everglades National Park

© Cengage Learning 2015 Big Cypress National Preserve

© Cengage Learning 2015 Okefenokee Swamp in Georgia

© Cengage Learning 2015 Human activities –Threaten and disrupt ecosystem and economic services provided by freshwater lakes, rivers, and wetlands 8-5 How Have Human Activities Affected Freshwater Ecosystems?

© Cengage Learning 2015 Dams and canals restrict the flows of rivers –40% of the world’s largest rivers Flood-control destroys aquatic habitats and alters wetlands Cities and farms pollute water Many wetlands have been drained for human purposes Human Activities Are Disrupting and Degrading Freshwater Systems

© Cengage Learning 2015 Water dominates the planet –Saltwater and freshwater aquatic life zones cover almost three-fourths of the earth’s surface The earth’s aquatic systems provide important ecosystem and economic services Three Big Ideas

© Cengage Learning 2015 Human activities threaten biodiversity and disrupt ecological and economic services provided by aquatic systems Three Big Ideas (cont’d.)

© Cengage Learning 2015 Coral reefs: –Thrive on solar energy –Participate in nutrient cycling –Sustain aquatic biodiversity In nature, everything is connected How can we can reduce harm to coral reefs? Tying It All Together: Coral Reefs and Sustainability