Chapter 6 Major Ecosystems of the World Lecture Outline

Chapter 6

Major Ecosystems of the World
Lecture Outline:

1. 
   Earth’s Major Biomes
   
   1. 
      A biome is a large, relatively distinct terrestrial region with a similar climate, soil, plants, and animals
      
      1. 
         It encompasses many interacting ecosystems
         
      2. 
         It is considered the next level of ecological organization above those of community, ecosystem, and landscape
         
   2. 
      Tundra (arctic tundra): cold boggy plains of the far north
      
      1. 
         Tundra is a treeless biome consisting of boggy plains covered by lichens and small plants such as mosses
         
         1. 
            It has harsh, cold winters and extremely short summers
            
         2. 
            It is characterized by little precipitation (4-10 inches/yr), permafrost, low species richness, and low primary productivity
            
      2. 
         Animal life includes lemmings, voles, weasels, arctic foxes, snowshoe hairs, ptarmigan, snowy owls, and musk oxen
         
   3. 
      Boreal forests (taiga): conifer forests of the north
      
      1. 
         Boreal forest is a region of coniferous forest (such as pine, spruce, and fir) in the Northern Hemisphere; located just south of the tundra
         
         1. 
            It has extremely cold, severe winters
            
         2. 
            It is characterized by little precipitation (20 inches/year), acidic/mineral poor soil, ponds, lakes, and cone-bearing evergreens
            
      2. 
         Animal life includes caribous, wolves, bears, moose, rodents, rabbits, lynx, sable and mink
         
   4. 
      Temperate rain forest: lush temperate forests
      
      1. 
         Temperate rain forest occurs on the northwest coast of North America, southeastern Australia and southern South America, and consists mostly of large evergreen trees, mosses, lichens, and ferns
         
         1. 
            Seasonal fluctuation is narrow; winters are mild and summers are cool
            
         2. 
            It is characterized by high precipitation (50 inches/year), dense fog, high species richness, and high primary productivity
            
      2. 
         Animal life includes squirrels, wood rats, mule deer, elk, birds, and several amphibian and reptile species
         
   5. 
      Temperate deciduous forest: broad-leaved trees that shed their leaves
      
      1. 
         Temperate deciduous forest occurs in temperate areas with a moderate amount of precipitation
         
         1. 
            It has wide seasonal fluctuation with hot summers and cold winters
            
         2. 
            It is characterized by moderate precipitation (30 – 60 inches/year), rich top soil, and broad-leaf hardwood trees that lose their foliage annually
            
      2. 
         Animal life includes large mammals (puma, wolves, bison, deer, bears) and many small mammals and birds
         
   6. 
      Grasslands (tallgrass prairies): temperate seas of grass
      
      1. 
         Temperate grasslands contain a profusion of grasses and other herbaceous flowering plants and few trees
         
         1. 
            It has wide seasonal fluctuation with hot summers and cold winters
            
         2. 
            It is characterized by moderate precipitation (10-30 inches/yr) and a mineral rich top layer of soil ideal for agriculture
            
      2. 
         Animal life includes grazing mammals such as pronghorn elk and bison, wolves, coyotes, prairie dogs, foxes, ferrets, birds of prey, grouse, reptiles, and insects
         
   7. 
      Chaparral (mediterranean climates): thickets of evergreen shrubs and small trees
      
      1. 
         Chaparral is a hilly temperate biome located around the Mediterranean Sea as well as in the North American southwest, southwestern and southern Australia, central Chile, and southwestern South Africa
         
         1. 
            It has mild winters with abundant rainfall combined and dry summers; files are common during summer months
            
         2. 
            It is characterized by low precipitation (mostly in winter),dense growth of evergreen shrubs, small trees, and thin, unfertile soil
            
      2. 
         Animal life includes mule deer, wood rats, chipmunks, lizards, and many species of birds
         
   8. 
      Deserts: arid life zones
      
      1. 
         Deserts are dry areas found in both temperate (cold deserts) and subtropical regions (warm deserts) usually with sparse plant cover of cacti, yuccas, Joshua trees and sagebrushes
         
         1. 
            The low water vapor content of the desert atmosphere results n daily temperature extremes of heat and cold;
            
         2. 
            They are characterized by low precipitation (less than 10 inches/yr), very little plant life, low species richness, and soil low in organic material but high in mineral content
            
      2. 
         Animal life includes small mammals, insects amphibians, and reptiles (most are desert adapted)
         
   9. 
      Savanna: tropical grasslands
      
      1. 
         Savannas are tropical grasslands with widely scattered trees or clumps of trees
         
         1. 
            They usually occur in areas of low and/or seasonal rainfall with prolonged dry periods, temperature varies little throughout the year, and seasons are regulated by precipitation
            
         2. 
            Annual precipitation is moderate (30-60 inches/yr), soil is low in nutrient minerals, both trees and grasses have fire-adapted features and protection against herbivores
            
      2. 
         Animal life includes hoofed mammals (antelope, giraffe, zebra elephants), large predators (lions and hyenas), many bird species, and cattle (present rangeland grazing is leading to desertification of savannas)
         
   10. 
       Tropical rain forests: lush equatorial forests
       
       1. 
          Tropical rain forests are lush, species-rich forest biomes that occur where the climate is warm and moist throughout the year
          
          1. 
             They are found in Central and South America, Africa, and Southeast Asia and are typically home to evergreen flowering plants, epiphytes, tall trees, and three distinct layers of vegetation
             
          2. 
             It is characterized by high annual precipitation (80 – 180 inches/yr), ancient, highly weathered mineral-poor soil, high productivity, and high species richness
             
       2. 
          Animal life includes an enormous array of insects, reptiles, amphibians, birds, and mammals (sloths and monkeys)
          
   11. 
       Vertical zonation: the distribution of vegetation on mountains
       
       1. 
          The cooler temperatures at higher elevations of a mountain produce a series of ecosystems similar to the biomes encountered when going toward the North Pole (deciduous/temperate forest, subalpine coniferous/boreal forest, alpine/arctic tundra)
          
       2. 
          Types of organisms living on the mountain change as the temperature changes
          
2. 
   Aquatic Ecosystems
   
   1. 
      Determinants of species composition in aquatic ecosystems include salinity, dissolved oxygen, light, temperature, pH, and presences or absence of waves and currents
      
   2. 
      Aquatic ecosystems contain three main ecological categories of organisms
      
      1. 
         Free-floating plankton
         
         1. 
            Phytoplankton are free-floating photosynthetic algae and cyanobacteria that form the base of most aquatic food webs
            
         2. 
            Zooplankton are nonphotosynthetic organisms that include protozoa, crustaceans, and the larval stages of many animals
            
      2. 
         Strongly swimming nekton (fishes, turtles, whales)
         
      3. 
         Bottom-dwelling benthos (sponges, oysters, barnacles, worms, clams, sea cucumbers, crawfish, insect larvae, brittle stars)
         
   3. 
      Freshwater ecosystems (occupy only about 2% of Earth’s surface)
      
      1. 
         Rivers and streams: flowing-water ecosystems
         
         1. 
            The concept of a river system as a single ecosystem with a gradient in physical features from headwaters to mouth is known as the river continuum concept
            
         2. 
            This gradient results in predictable changes in the organism inhabiting different parts of the river system
            
      2. 
         Lakes and ponds: standing-water ecosystems
         
         1. 
            A large lake has three zones
            
            1. 
               The littoral zone is a shallow-water area along the shore of a lake or pond where light reaches the bottom; it is the most productive section of the lake
               
            2. 
               The limnetic zone is the open water beyond the littoral zone; it extends down as far as sunlight penetrates to permit photosynthesis
               
            3. 
               The profundal zone is beneath the limnetic zone; light does not penetrate effectively to this depth (no plants or algae found here)
               
      3. 
         Thermal stratification and turnover in temperate lakes
         
         1. 
            Thermal stratification is the marked layering of large temperate lakes caused by how far light penetrates it, causing temperature to change sharply with depth
            
         2. 
            Falling temperatures in fall, and rising temperatures in spring cause turnover, a mixing of the layers of lake water
            
      4. 
         Marshes and swamps: freshwater wetlands
         
         1. 
            Grasslike plants dominate in marshes, while woody trees and/or shrubs dominate in swamps
            
         2. 
            Wetlands are valued wildlife habitat for migratory birds, beaver, otters, muskrats, and game fishes
            
         3. 
            They provide natural flood control and serve as groundwater recharging areas
            
   4. 
      Estuaries: where fresh and salt water meet
      
      1. 
         Estuaries are among the most fertile ecosystems in the world
         
      2. 
         Temperate estuaries usually contain salt marshes which are important in preventing flood damage during storm surges
         
      3. 
         Mangrove forests are the tropical equivalent of salt marshes; they cover nearly 70% of tropical coastlines
         
         1. 
            Mangroves are breeding ground and nurseries for several commercially important fishes, shellfish, and birds
            
         2. 
            They also help prevent coastal erosion and provide a barrier against the ocean during storms/hurricanes
            
   5. 
      Marine ecosystems
      
      1. 
         The intertidal zone is the area of shore line between low and high tides
         
      2. 
         The benthic environment: seagrass beds, kelp forests, and coral reefs
         
         1. 
            The benthic environment consists of sediments (mostly sand and mud) where many animals burrow
            
         2. 
            Shallow benthic communities are particularly productive
            
            1. 
               Seagrass beds are flowering plants adapted to complete submersion in salty ocean water; they are areas of high primary productivity and help stabilize sediments, reducing surface erosion
               
            2. 
               Kelp forests provide habitats for many marine animals; the diversity of life supported by kelp forests rivals that found in coral reefs
               
            3. 
               Coral reefs are found in warm shallow seawater; they consist of colonies of millions of tiny coral animals, which require light for zooxanthellae (the symbiotic algae that live and photosynthesize in their tissues)
               
               1. 
                  Coral reefs are ecologically important because they provide a habitat for many kinds of marine organisms and protect coastlines from shoreline erosion
                  
               2. 
                  There are three main types of coral reefs
                  
                  1. 
                     Fringing reefs are directly attached to the shore of a volcanic island or continent
                     
                  2. 
                     Atolls are circular coral reefs that surround a central lagoon of quiet water
                     
                  3. 
                     Barrier reefs are separated from nearby land by a lagoon of open water
                     
               3. 
                  Various human activities cause serious threats to the health of coral reefs (runoff, overfishing, disease, etc.)
                  
         3. 
            Deeper parts of the benthic environment are divided into three zones
            
            1. 
               Bathyal benthic zone – 200m to 4000m
               
            2. 
               Abyssal benthic zone – 4000m to 6000m
               
            3. 
               Hadal benthic zone – 6000m to the bottom of the deepest trenches
               
      3. 
         The pelagic environment: the vast marine system
         
         1. 
            The pelagic environment consists of all of the ocean water, from the shoreline down to the deepest ocean trenches
            
            1. 
               The upper reaches of the pelagic environment comprise the euphotic zone
               
            2. 
               The euphotic zone spans from the surface to 150m deep
               
         2. 
            The two main divisions of the pelagic environment are the neritic and oceanic provinces
            
            1. 
               The part of the pelagic environment that overlies the ocean floor from the shoreline to a depth of 200m is referred to as the neritic province
               
            2. 
               The part of the pelagic environment that overlies the ocean floor at depths greater than 200m is referred to as the oceanic province
               
      4. 
         A national marine sanctuary is a marine ecosystem set aside to minimize human impacts and protect unique natural resources and historical sites
         
         1. 
            The U.S. has 14 national marine sanctuaries along the Atlantic, Pacific, and Gulf of Mexico coasts
            
         2. 
            They include kelp forests, coral reefs, fishing grounds, deep submarine canyons and shipwrecks
            

In-Class Activities:

Instructor Notes for In-Class Activity 1

Title:	Recognizing Biomes
Time:__5_minutes_prep;_60_minutes_out_of_class_time;_one_class_period_for_presentations__Materials'>Time:__0_minutes_prep;_15_–_25_minutes_in_class__Materials'>Time:	0 minutes prep; 15 – 25 minutes in class
Materials:__Internet_access__Handouts'>Materials:	None
Handouts:	None
Procedures:	First, have students vote (anonymously) for the kind of biome your campus is located in. First, have them make a guess, then have them do research on the internet to find exact climate data for your area. Discuss: was your intuitive sense accurate? Why or why not. Next, have each student identify the farthest away location that they have visited. What sort of biome was it? How do we know? Again, use the internet to find the data you would need to confirm this biome. Discuss how plant and animal life (including behavior of humans in that location) differ from those in your region.
Student Instructions:	See above
Specific Suggestions:	None
Objectives:__Define_biome_and_describe_some_of_the_major_terrestrial_biomes.___Instructor_Notes_for_In-Class_Activity_2'>Objectives:	Define biome and describe some of the major terrestrial biomes.

Instructor Notes for In-Class Activity 2

Title:	Drilling for Oil in the Tundra
Time:	5 – 10 Minutes prep; 40 – 60 minutes in class (or can assign research between class periods)
Materials:	Internet access
Handouts:	None
Procedures:	For – Against – Jury standard procedure. Randomly divide class into three groups. Statement: Extracting Oil from the Alaskan National Wildlife Refuge will have a minimal impact on local plants and animals. Assign one group each to argue FOR or AGAINST the statement, and the third group to serve as a JURY. Each group should select a leader and a recorder. The FOR group should research (not just think up!) information that supports the statement. They should be explicit about their sources, whether those are data, ethics, theories, or political positions. They should then synthesize this into a five-minute verbal argument, to be made before the full class. The AGAINST group should do the same for the opposite position. Their original argument SHOULD NOT respond to items brought up by the FOR group. After each has made a five-minute argument, each side will have two minutes to respond to claims or statements made by the other side. The JURY group will then deliberate openly; the FOR and AGAINST groups will listen to the deliberations, but may not respond. The JURY may challenge either group to provide evidence for up to three pieces of information, and may ask up to three questions of each group (they may ask the same question to both groups). The JURY should then make two judgments: Which, if either, provided the most credible INFORMATION Which provided the most compelling overall argument. Be sure students argue their points forcefully, whether or not they believe them personally.
Student Instructions:	See above
Specific Suggestions:	The instructor is likely to have to serve as a facilitator or moderator from time to time Do not allow personal assaults Feel free to challenge pieces of information that you find dubious if the JURY does not. It will probably take a couple times through this debate process before you and your class are comfortable with it.
Objectives:	Relate human effects on biomes.

Instructor Notes for In-Class Activity 3

Title:	Field Trip: Zoo, Botanical Gardens, Natural History Museum or Campus
Time:	5 – 30 minutes prep; Full class period
Materials:	None
Handouts:	Printed materials from the destination, if available
Procedures:	Visit a local zoo, botanical garden, natural history museum or even your campus. Have students take notes on the types of animals and plants from biomes other than your regions biome. In the cases of living organisms, discuss what steps people have to take to maintain those organisms. Upon returning to class, discuss your findings.
Student Instructions:	Prepare your own definition of a biome. Then, during the field trip, think about how completely your definition captures the examples you encounter. Adapt your definition as necessary.
Specific Suggestions:	Have specific students assigned to discuss and then look into a specific biome.
Objectives:	Define biome and describe at least one of the major terrestrial or aquatic biomes.

Instructor Notes for In-Class Activity 4

Title:	Travel to a Biome
Time:	5 minutes prep; 60 minutes out of class time; one class period for presentations
Materials:	None
Handouts:	None
Procedures:	Divide the class into groups of two or three individuals. If there are 30 in the class have groups of three, if there are fewer students, groups of two work best. Have each group draw a biome out of a hat. This way you are not assigning a biome and the student have more control over what they putting together. Each student group is to come up with a travel agency name and they will try and recruit their classmates to go on a trip to their biome. Artic biome and Aquatic biomes are great challenges. The students will then go and put a presentation with flyers, prices, a power point presentation explaining their biome and why we would want to vacation at this particular biome. They must put the temperatures, conditions, what we need to bring, what kind of activities take place, what animals or plants live in this biome etc. On the presentation day, they will be presenting this biome as a marketing tool to get us to venture to the desert, mountains, tropical rain forests etc. At the end of the presentations, the student group with the most votes to travel to that biome will receive additional 25 points for the assignment. Other rewards could be given, like a travel bag from a travel agency etc.
Student Instructions:	You and your team will need to come up with the ideal vacation to go to your chosen biome. You will make a power point presentation on your biome giving information on the temperatures, activities, who and what lives there, what we need to bring, how much it will cost and why we should choose your biome over the other biomes that will be presenting.
Specific Suggestions:	None
Objectives:	Describe the different biomes and their impact on our ecology. Identify different characteristics of a biome and the impact to living organism in that biome.

Instructor Notes for In-Class Activity 5

Title:	Finger shuffle board
Time:	25 minutes prep; 15 – 25 minutes in class.
Materials:	Blow up Figure 6.2 to 8x11 size put shuffle board points on each shelf and laminate it. Have enough for each student. Each student can supply their own penny but you should have enough for each student if needed.
Handouts:	Hand out Figure 6.2 which is laminated with points on it.
Procedures:	Pass out the shuffle boards to each student, they will pair up into two students per group. They will sit across from each other with their laminated shuffle board paper, a penny each. Each student takes a turn and shoots their penny toward the board with the blue point facing them. They must describe the biome they hit and list some benefits of that biome. If they state one point they get the points they hit. If they cannot describe the biome, or give a point not given they will lose that number of points. The person who has the most points in a 15-minute period advances to the next level. This is a good way to study for the biomes.
Student Instructions:	Have your biome shuffleboard pictures pointing away from you. Face your partner. Decide who goes first and that person will then flick his/her penny towards the board across from them. When the penny falls on a field or biome, they are to describe one point of that biome. It could be the average temperature, type of animals or plants that live in that biome, why this particular biome is good for our environment etc. If they state one fact, they get the points on the board. Each person keeps track of their points and after 15 minutes the person with the most points advances to the next level which is another class member that has the most point. The game is then started all over until there is a classmate with the top points. You carry your points from one game to the next.
Specific Suggestions:	None
Objectives:	Describe the different biomes. List or describe the benefits of the biomes in our environment.

Answers to Thinking About the Environment

End of Chapter Questions:
1. Offer a possible reason why the tundra has such a low species richness.
Ans: The limited precipitation in combination with low temperatures, flat topography (surface features), and the permafrost. Few species have specialized to this environment. Another reason for low species richness may be the short growing season which results in low primary productivity.
2. Relate the tundra’s temperature and precipitation to its biotic characteristics.
Ans: Animals that occur on the tundra must be able to survive the long harsh winters and cold temperatures or migrate seasonally. Mosquitoes, blackflies, and deerflies survive the winter as eggs or pupae, and adults occur in great numbers during summer. Caribou and dozens of birds species migrate north in summer. Although precipitation is low soil is usually waterlogged because permafrost interferes with drainage. Plant species are then limited to those that can survive waterlogged conditions and extreme cold.
3. Describe representative organisms of the forest biomes discussed in the text: boreal forest, temperate deciduous forest, temperate rain forest, and tropical rain forest.
Ans: Black and white spruces, balsam fir, eastern larch, and other conifers (cone-bearing evergreens) dominate the boreal forest. Conifers have many drought-resistant adaptations, such as needlelike leaves with a minimal surface area for water loss. Such an adaptation lets conifers withstand the “drought” of the northern winter months when roots cannot absorb water because the ground is frozen. Being evergreen, conifers resume photosynthesis as soon as warmer temperatures return. Animals in the boreal forest include; caribou, which migrate from the tundra in the summer, wolves, bears, moose, lynx, sable, and mink. Most species of birds are abundant in the summer but migrate to warmer climates for winter.
The temperate deciduous forest is dominated by broad-leaved hardwood trees, such as oak, hickory, maple, and beech, that lose their foliage annually. The trees of the temperate deciduous forest form a dense canopy that overlies saplings and shrubs.

Temperate deciduous forests originally contained a variety of large mammals, such as puma, wolves, and bison, which are now absent, plus deer, bears, and many small mammals and birds.

The dominant plants in the North American temperate rain forest are large evergreen trees such as western hemlock, Douglas fir, western red cedar, Sitka spruce, and western arborvitae. Temperate rain forests are rich in epiphytic vegetation—smaller plants that grow on the trunks and branches of large trees. Epiphytes in this biome are mainly mosses, club mosses, lichens, and ferns, all of which also carpet the ground. Deciduous shrubs such as vine maple grow wherever a break in the overlying canopy occurs. Squirrels, wood rats, mule deer, elk, numerous bird species, and several species of amphibians and reptiles are common temperate rainforest animals.
No single species dominates the tropical rain forest. The trees of tropical rain forests are typically evergreen flowering plants. Their roots are often shallow and concentrated near the surface in a mat. The root mat catches and absorbs almost all nutrient minerals released from leaves and litter by decay processes. Swollen bases or braces called buttresses hold the trees upright and aid in the extensive distribution of the shallow roots. Little light penetrates to the understory, and many plants living there are adapted to climb already established host trees. Not counting bacteria and other soil-dwelling organisms, about 90% of tropical rainforest organisms live in the upper canopy. Rainforest animals include the most abundant and varied insects, reptiles, birds and amphibians on Earth. Most rainforest mammals, such as sloths and monkeys, live only in the trees and rarely climb to the ground.
4. In which biome do you live? If your biome does not match the description given in this book, how do you explain the discrepancy?
Ans: Answers will vary
5. Which biomes are best suited for agriculture? Explain why each of the biomes you did not specify is less suitable for agriculture.
Ans: The biomes most suited for agriculture are temperate deciduous forest and grasslands. Tundra is not suitable for agriculture because it is to cold and has water logged soil. Boreal forest is not suitable because it has a short growing season and mineral poor soil. Chaparral and savanna biomes have evolved with fire and need frequent fires to release nutrients back into the soil. Desert biomes are too dry for most agricultural products. Tropical rain forest are not good for agriculture because little organic matter accumulates in the soil.
6. What human activities are harmful to deserts? to grasslands? to forests?
Ans: Off-road vehicles damage desert vegetation, which sometimes takes years to recover. When the top layer of desert soil is disturbed, erosion occurs more readily, and less vegetation grows to support native animals. In some savanna grasslands, severe overgrazing and harvesting of trees for firewood have converted savanna to desert, a process called desertification. In all forests overharvesting leads to deforestation and lost of species habitat.
7. Which biome do you think is in greatest immediate danger from human activities? Why?
Ans: Answers will vary
8. What would happen to the organisms in a river with a fast current if a dam were built? Explain your answer.
Ans: In streams with fast currents, the inhabitants may have adaptations such as hooks or suckers to attach themselves to rocks so that they are not swept away. A dam causes water to back up, flooding large areas of land and forming a reservoir, which destroys terrestrial habitat. Below the dam, the once-powerful river is often reduced to a relative trickle, which alters water temperature, sediment transport, and delta replenishment and prevents fish migrations. The organisms that are adapted for fast currents will be out competed by species better suited for the new conditions.
9. Explain the role of freshwater wetlands in water purification.
Ans: One of freshwater wetlands most important roles is to help cleanse water by trapping and holding pollutants in the flooded soil. Wetlands also provide natural flood control because they are holding areas for excess water when rivers flood their banks. The floodwater stored in wetlands then drains slowly back into the rivers, providing a steady flow of water throughout the year. Wetlands serve as groundwater recharging areas.
10. If you were to find yourself on a boat in the Chesapeake Bay, what aquatic ecosystem would you be in? What ecosystem would you be in if you were in the middle of Everglades National Park?
Ans: The Chesapeake Bay is an estuary- A coastal body of water, partly surrounded by land, with access to the open ocean and a large supply of fresh water from a river. Everglades National Park is a salt marsh- shallow wetlands dominated by salt-tolerant grasses.
11. Which aquatic ecosystem is often compared to a tropical rain forest? Why?
Ans: Coral reef ecosystems are the most diverse of all marine environments. They contain thousands of species of fishes and invertebrates, such as giant clams, snails, sea urchins, sea stars, sponges, flatworms, brittle stars, sea fans, shrimp, and spiny lobsters. The Great Barrier Reef occupies only 0.1% of the ocean's surface, but 8% of the world's fish species live there. The multitude of relationships and interactions that occur at coral reefs is comparable only to tropical rain forests among terrestrial ecosystems.
12. Explain how coral reefs are vulnerable to human activities.
Ans: Globally, many coral reefs are at risk. In some areas, silt washing downstream from clearcut inland forests has smothered reefs under a layer of sediment. In addition to pollution from coastal runoff, overfishing, fishing with dynamite or cyanide, disease, and coral bleaching are serious threats. Land reclamation, tourism, oil spills, boat groundings, anchor draggings, hurricane damage, ocean dumping, and the mining of corals for building material also take a toll.
13. What is the largest marine environment, and what are some of its features?
Ans: The oceanic province is the largest marine environment, comprising about 75% of the ocean's water; the oceanic province is the open ocean that does not overlie the continental shelf. Most of the oceanic province is loosely described as the “deep sea.” All but the surface waters of the oceanic province have cold temperatures, high hydrostatic pressure, and an absence of sunlight. These environmental conditions are uniform throughout the year.

14. Briefly discuss two major human-caused problems in the ocean.

Ans: Answers may include any two of the following: Coastal and marine ecosystems receive pollution from land, from rivers emptying into the ocean, and from atmospheric contaminants that enter the ocean via precipitation. Disease-causing viruses and bacteria from human sewage contaminate seafood, such as shellfish, and pose an increasing threat to public health. Millions of tons of trash, including plastic, fishing nets, and packaging materials, find their way into coastal and marine ecosystems. Less visible contaminants of the ocean include fertilizers, pesticides, heavy metals, and synthetic chemicals from agriculture and industry. Offshore mining and oil drilling pollute the neritic province with oil and other contaminants. Millions of ships dump oily ballast and other wastes overboard in the neritic and oceanic provinces. Fishing is highly mechanized, and new technologies detect and remove every single fish in a targeted area of the ocean.
15. A 2003 study reports that in recent years tropical ocean waters have become saltier, whereas polar ocean waters have become less salty. What do you think is a possible explanation for these changes?
Ans: Answers will vary.
16. In modeling the Chesapeake Bay system, scientists consider the following health indicators for the bay, which are organized into three categories. Pick two human-caused problems and explain how each affects the biotic and abiotic components of the Chesapeake Bay system.

Ans: Answers may include two of the following:

Nutrient pollution (most often nitrogen), empties into the bay from agricultural runoff, sewage treatment plants, electric power companies, and motor vehicles. Most of this pollution remains in the bay, causing excessive algal growth that results in a much lower level of dissolved oxygen in the water. Oxygen-deprived water suffocates oysters, crabs, and other aquatic organisms.

Sediment pollution can alter water circulation patterns, if freshwater flow into the estuary is blocked or limited salinity in the Bay will increase. Excess sediment can suffocate benthic organisms and destroy marshes which are nurseries for many fish species.
Toxicant pollution may not alter any of the abiotic aspects of the Chesapeake Bay but it will affect all aspects of the biotic ecosystem. Persistent toxicants biomagnify as they go from low trophic levels (planton) to higher trophic levels (shellfish and finfish).
Overfishing disrupts the balance of producers, consumers, and decomposers. For example, if to many algae eating fish are removed algae populations can over grow causing decreased dissolved oxygen levels in the water. Oxygen-deprived water suffocates oysters, crabs, and other aquatic organisms.
Unsound land use can alter water flow patterns, water circulation and salinity. This will affects all of the biotic communities by adding or removing habitat.

Answers to Review Questions
Earth’s Major Biomes (p. 129)
1. What is a biome? What two climate factors are most important in determining an area's characteristic biome?
Ans: A biome is a large, relatively distinct terrestrial region with a similar climate soil, plants, and animals, regardless of where it occurs in the world. Near the poles, temperature is generally the overriding climate factor, whereas in temperate and tropical regions, precipitation becomes more significant than temperature
2. What climate and soil factors produce each of the major terrestrial biomes?
Ans: Tundra is found in areas where winters are long and summers short. There is little precipitation (10 to 25cm per year) with most of it falling during the summer months. Most tundra soils are geologically young because they formed when glaciers retreated after the last Ice Age. In the boreal forest winters are extremely cold and severe, although not as harsh as in the tundra.
Boreal forest receives little precipitation, perhaps 50 cm per year, and its soil is typically acidic and mineral-poor, with a deep layer of partly decomposed pine and spruce needles at the surface.
In temperate rain forests winters are mild and summers are cool. Annual precipitation in this biome is high, more than 127 cm per year, and is augmented by condensation of water from dense coastal fogs. Temperate rain forest has relatively nutrient-poor soil, although its organic content may be high.
Temperate deciduous forest, which occurs in temperate areas where precipitation ranges from about 75 to 150 cm annually. Typically, the soil of a temperate deciduous forest consists of a topsoil rich in organic material and a deep, clay-rich lower layer.
Grasslands have hot summers and cold winters with annual precipitation averages 25 to 75 cm. Grassland soil has considerable organic material because the aerial portions of many grasses die off each winter and contribute to the organic content of the soil, whereas the roots and rhizomes (underground stems) survive.
Chaparral biomes have mild winters with abundant rain and dry summers. Chaparral soil is thin and often not fertile.
Deserts are dry areas found in doth temperate and subtropical regions. The low water vapor content of the desert atmosphere results in daily temperature extremes of heat and cold, and a major change in temperature occurs in a single 24-hour period. Generally, less than 25 cm of rain fall per year. As a result of sparse vegetation, desert soil is low in organic material but is often high in mineral content.
In savanna biomes temperature varies little throughout the year seasons are regulated by precipitation, not by temperature as they are in temperate grasslands. Annual precipitation is 76 to 150 cm. Savanna soil is somewhat low in essential nutrient minerals.
Tropical rain forests climate is warm and moist, the annual precipitation of a tropical rain forest is typically from 200 to 450 cm. Tropical rain forest commonly occurs in areas with ancient, highly weathered, mineral-poor soil.
3. How does vegetation change with increasing elevation and latitude?
Ans: Similar ecosystems are encountered in climbing a mountain (increasing elevation) and traveling to the North Pole (increasing latitude). This elevation-latitude similarity occurs because the temperature drops as one climbs a mountain, just as it does when one travels north.

Aquatic Ecosystems (p. 143)
1. What environmental factors are most important in determining the kinds of organisms found in aquatic environments?
Ans: In aquatic ecosystems, important environmental factors include salinity, amount of dissolved oxygen, and availability of light for photosynthesis.
2. How do you distinguish between freshwater wetlands and estuaries? Between flowing-water and standing-water ecosystems?
Ans: Freshwater wetlands are lands that shallow fresh water covers for at least part of the year; wetlands have a characteristic soil and water-tolerant vegetation. An estuary is a coastal body of water, partly surrounded by land, with access to the open ocean and a large supply of fresh water from a river. A flowing-water ecosystem is a freshwater ecosystem such as a river or stream in which the water flows in a current. A standing-water ecosystem is a body of fresh water that is surrounded by land and that does not flow (a lake or a pond).
3. What are the four main marine environments?
Ans: Four important marine environments are the intertidal zone, benthic environment, neritic province, and oceanic province.
4. Which marine environment is transitional between land and ocean?
Ans: The intertidal zone is the area of shoreline between low and high tides.
5. How do the neritic and oceanic provinces differ?
Ans: The pelagic environment consists of all of the ocean water, from the shoreline down to the deepest ocean trenches. The two main divisions of the pelagic environment are the neritic and oceanic provinces. The neritic province is the part of the pelagic environment that overlies the ocean floor from the shoreline to a depth of 200 m. The oceanic province is the part of the pelagic environment that overlies the ocean floor at depths greater than 200 m.
6. What are four purposes of national marine sanctuaries?
Ans: The National Oceanic and Atmospheric Administration (NOAA) administers the sanctuaries for multiple purposes, including conservation, recreation, education, mining, scientific research, ship salvaging, and commercial fishing.

Interaction of Life Zones and Humans (p. 145)
1. How did the Florida Everglades get so degraded?
Ans: Two problems have led to the degradation of the everglades, it receives too little water, and the water it receives is polluted with nutrient minerals from agricultural runoff.
2. What are some of the challenges associated with restoration of the Florida Everglades?
Ans: one major challenge is supplying clean, fresh water to the Everglades and to the fast-growing population of South Florida. Other questions remain about how best to restore a more natural water flow, repel invasions of foreign species, and reestablish native species.