1. The Biosphere: An introduction to Earth’s Diverse Environments
Chapter 34
The Biosphere: An introduction to Earth’s Diverse Environments

2. Introduction
For most of life on Earth, the sun is the main source of energy.
But around hydrothermal vents, life depends on chemoautotrophic sulfur bacteria.
From the roof of the world to the deepest oceans, Earth’s diverse environments are bursting with life.
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3. Figure 34.0_1
Figure 34.0_1 Unit Seven: Ecology (Poison dart frog) 3

4. Chapter 34: Big Ideas The Biosphere Aquatic Biomes Terrestrial Biomes
Figure 34.0_2
Chapter 34: Big Ideas
The Biosphere
Aquatic Biomes
Figure 34.0_2 Chapter 34: Big Ideas
Terrestrial Biomes 4

5. Figure 34.0_3
Figure 34.0_3 The rocky slopes of the eastern Himalayas 5

6. THE BIOSPHERE
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7. 34.1 Ecologists study how organisms interact with their environment at several levels
Ecology is the scientific study of the interactions of organisms with their environments.
Organisms can potentially be affected by many different variables, grouped into two major types.
1. Biotic factors include all of the organisms in an area, the living component of the environment.
2. Abiotic factors are the environment’s nonliving component, the physical and chemical factors.
An organism’s habitat includes the biotic and abiotic factors present in its surroundings.
Student Misconceptions and Concerns
Students may confuse the terms ecology and environmentalism. The science of ecology and the environmental issues that it often raises are related but distinct processes.
Teaching Tips
In the first chapter of the text, Module 1.2 introduces the levels of biological organization extending from an atom to the biosphere. Reviewing these with students will help them to place these ecology chapters in context.
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8. 34.1 Ecologists study how organisms interact with their environment at several levels
Ecologists study environmental interactions at the levels of the
organism,
population, a group of individuals of the same species living in a particular geographic area,
community, an assemblage of all the populations of organisms living close enough together for potential interaction, and
ecosystem, both the abiotic and biotic components of the environment.
Student Misconceptions and Concerns
Students may confuse the terms ecology and environmentalism. The science of ecology and the environmental issues that it often raises are related but distinct processes.
Teaching Tips
In the first chapter of the text, Module 1.2 introduces the levels of biological organization extending from an atom to the biosphere. Reviewing these with students will help them to place these ecology chapters in context.
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9. Figure 34.1A
Figure 34.1A An organism 9

10. Figure 34.1B
Figure 34.1B A population 10

11. Figure 34.1C
Figure 34.1C A community 11

12. Figure 34.1D
Figure 34.1D An ecosystem 12

13. 34.1 Ecologists study how organisms interact with their environment at several levels
Some ecologists take a wider perspective by studying landscapes, arrays of ecosystems usually visible from the air as distinctive patches.
The biosphere
extends from the atmosphere several kilometers above Earth to the depths of the oceans and
is all of the Earth that is inhabited by life.
Student Misconceptions and Concerns
Students may confuse the terms ecology and environmentalism. The science of ecology and the environmental issues that it often raises are related but distinct processes.
Teaching Tips
In the first chapter of the text, Module 1.2 introduces the levels of biological organization extending from an atom to the biosphere. Reviewing these with students will help them to place these ecology chapters in context.
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14. 34.2 CONNECTION: The science of ecology provides insight into environmental problems
Human activities affect all parts of the biosphere.
Cities, farms, and highways change the landscape.
The widespread use of chemicals such as fertilizers and pesticides poses problems to people and other organisms.
Student Misconceptions and Concerns
Students may confuse the terms ecology and environmentalism. The science of ecology and the environmental issues that it often raises are related but distinct processes.
Teaching Tips
A website devoted to Rachel Carson can be viewed at
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15. Figure 34.2A
Figure 34.2A An aerial view of a landscape changed by humans 15

16. 34.2 CONNECTION: The science of ecology provides insight into environmental problems
Two events raised questions about the long-term effects of widespread DDT use.
The evolution of pesticide resistance in insects and
Rachel Carson’s 1962 book Silent Spring, which played a key role in the awakening of environmental awareness.
Student Misconceptions and Concerns
Students may confuse the terms ecology and environmentalism. The science of ecology and the environmental issues that it often raises are related but distinct processes.
Teaching Tips
A website devoted to Rachel Carson can be viewed at
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17. Figure 34.2B
Figure 34.2B Rachel Carson 17

18. 34.3 Physical and chemical factors influence life in the biosphere
The most important abiotic factors that determine the biosphere’s structure and dynamics include
the energy source, usually solar energy,
temperature,
abundance and type of water,
nutrients,
other aquatic factors such as availability of oxygen, and
other terrestrial factors including wind and fire.
Student Misconceptions and Concerns
Students may confuse the terms ecology and environmentalism. The science of ecology and the environmental issues that it often raises are related but distinct processes.
Teaching Tips
1. As a class focusing exercise, consider challenging students to make lists of all the abiotic components in a given ecosystem. You might suggest a particular place to consider, such as a nearby park or other nearby area of natural interest. They may work in class in small groups, or turn the lists in as a short homework assignment (perhaps via ).
2. In general, the sun is the primary source of energy input to ecosystems. Hydrothermal vent communities are a clear exception. Some students might enjoy researching additional details about these ecosystems and the roles they might have played in the early evolution of life on Earth. One source of good information about hydrothermal vent communities is
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19. Figure 34.3A
Figure 34.3A The respiratory surface of a giant tube worm 19

20. Figure 34.3B
Figure 34.3B A snowy owl 20

21. 34.4 EVOLUTION CONNECTION: Organisms are adapted to abiotic and biotic factors by natural selection
One of the fundamental goals of ecology is to explain the distribution of organisms.
The presence of a species in a particular place has two possible explanations.
The species may have evolved from ancestors living in that location, or
it may have dispersed to that location and been able to survive once it arrived.
Student Misconceptions and Concerns
Students may confuse the terms ecology and environmentalism. The science of ecology and the environmental issues that it often raises are related but distinct processes.
Teaching Tips
Consider challenging your students to explain why organisms are typically limited to living in only certain parts of the biosphere. Module 34.4 notes that a species range may be limited by adaptations to particular environmental conditions. The same adaptations that permit survival under certain conditions may reduce survival rates under other conditions. Such trade-offs between specialization and generalization are a normal part of biology. If you want to emphasize the point with an analogy, you might note that choosing a particular major in college increases the student’s skills in that field, but comes at the cost of detailed study in other fields.
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22. 34.4 EVOLUTION CONNECTION: Organisms are adapted to abiotic and biotic factors by natural selection
The pronghorn is a highly successful herbivorous running mammal of open country.
It is a descendent of ancestors that roamed the open plains and shrub deserts of North America more than a million years ago.
It is found nowhere else and is only distantly related to the many antelope species in Africa.
Student Misconceptions and Concerns
Students may confuse the terms ecology and environmentalism. The science of ecology and the environmental issues that it often raises are related but distinct processes.
Teaching Tips
Consider challenging your students to explain why organisms are typically limited to living in only certain parts of the biosphere. Module 34.4 notes that a species range may be limited by adaptations to particular environmental conditions. The same adaptations that permit survival under certain conditions may reduce survival rates under other conditions. Such trade-offs between specialization and generalization are a normal part of biology. If you want to emphasize the point with an analogy, you might note that choosing a particular major in college increases the student’s skills in that field, but comes at the cost of detailed study in other fields.
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23. 34.4 EVOLUTION CONNECTION: Organisms are adapted to abiotic and biotic factors by natural selection
A pronghorn’s habitat is arid, windswept, and subject to extreme temperature fluctuations.
Their ability to survive and reproduce under these conditions left offspring that carried their alleles into subsequent generations.
Until around 12,000 years ago, one of their major predators was probably the now extinct American cheetah, similar to African cheetahs alive today.
Student Misconceptions and Concerns
Students may confuse the terms ecology and environmentalism. The science of ecology and the environmental issues that it often raises are related but distinct processes.
Teaching Tips
Consider challenging your students to explain why organisms are typically limited to living in only certain parts of the biosphere. Module 34.4 notes that a species range may be limited by adaptations to particular environmental conditions. The same adaptations that permit survival under certain conditions may reduce survival rates under other conditions. Such trade-offs between specialization and generalization are a normal part of biology. If you want to emphasize the point with an analogy, you might note that choosing a particular major in college increases the student’s skills in that field, but comes at the cost of detailed study in other fields.
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24. 34.4 EVOLUTION CONNECTION: Organisms are adapted to abiotic and biotic factors by natural selection
Ecologists hypothesize that the selection pressure of the cheetah’s pursuit led to the pronghorn’s blazing speed, which far exceeds that of its main present-day predator, the wolf.
Like many large herbivores that live in open grasslands, the pronghorn also derives protection from living in herds.
Populations of organisms are adapted to local environmental conditions, which may limit the distribution of organisms.
Student Misconceptions and Concerns
Students may confuse the terms ecology and environmentalism. The science of ecology and the environmental issues that it often raises are related but distinct processes.
Teaching Tips
Consider challenging your students to explain why organisms are typically limited to living in only certain parts of the biosphere. Module 34.4 notes that a species range may be limited by adaptations to particular environmental conditions. The same adaptations that permit survival under certain conditions may reduce survival rates under other conditions. Such trade-offs between specialization and generalization are a normal part of biology. If you want to emphasize the point with an analogy, you might note that choosing a particular major in college increases the student’s skills in that field, but comes at the cost of detailed study in other fields.
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25. Figure 34.4
Figure 34.4 A pronghorn (Antilocapra americana) 25

26. 34.5 Regional climate influences the distribution of terrestrial communities
Climate often determines the distribution of communities.
The Earth’s global climate patterns are largely determined by
the input of solar energy and
the planet’s movement in space.
Student Misconceptions and Concerns
Students may confuse the terms ecology and environmentalism. The science of ecology and the environmental issues that it often raises are related but distinct processes.
Teaching Tips
Module 34.5 discusses the reasons why Earth’s tilt causes seasons. Consider challenging your students, perhaps as a short in-class activity, to explain why it is typically cooler (a) further away from the equator and (b) during the winter months. Although you may not want to use class time on this activity every year, collecting student responses before your students read or learn about this in class can reveal misconceptions and areas of misunderstanding that will help direct your teaching for years to come.
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27. 34.5 Regional climate influences the distribution of terrestrial communities
Solar radiation varies with latitude.
Equatorial regions receive sunlight more directly.
Higher latitudes receive sunlight at more of a slant.
Most climatic variations are due to the uneven heating of Earth’s surface.
Student Misconceptions and Concerns
Students may confuse the terms ecology and environmentalism. The science of ecology and the environmental issues that it often raises are related but distinct processes.
Teaching Tips
Module 34.5 discusses the reasons why Earth’s tilt causes seasons. Consider challenging your students, perhaps as a short in-class activity, to explain why it is typically cooler (a) further away from the equator and (b) during the winter months. Although you may not want to use class time on this activity every year, collecting student responses before your students read or learn about this in class can reveal misconceptions and areas of misunderstanding that will help direct your teaching for years to come.
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28. Low angle of incoming sunlight 60N
Figure 34.5A
North Pole
Low angle of incoming sunlight
60N
30N
Tropic of Cancer
Sunlight strikes most directly
0 (equator)
Tropic of Capricorn
Figure 34.5A How solar radiation varies with latitude
30S
Low angle of incoming sunlight
60S
South Pole
Atmosphere 28

29. 34.5 Regional climate influences the distribution of terrestrial communities
The Earth’s permanent tilt causes the seasons.
In June, the Northern Hemisphere of the Earth is tipped toward the sun.
In December, the Northern Hemisphere of the Earth is tipped away from the sun.
The reverse is true about the Southern Hemisphere, generating opposite seasons during the same time of year.
Student Misconceptions and Concerns
Students may confuse the terms ecology and environmentalism. The science of ecology and the environmental issues that it often raises are related but distinct processes.
Teaching Tips
Module 34.5 discusses the reasons why Earth’s tilt causes seasons. Consider challenging your students, perhaps as a short in-class activity, to explain why it is typically cooler (a) further away from the equator and (b) during the winter months. Although you may not want to use class time on this activity every year, collecting student responses before your students read or learn about this in class can reveal misconceptions and areas of misunderstanding that will help direct your teaching for years to come.
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30. (equator faces sun directly)
Figure 34.5B
March equinox
(equator faces sun directly)
June solstice (Northern Hemisphere tilts toward sun)
Figure 34.5B How Earth’s tilt causes the seasons
Constant tilt of 23.5
December solstice (Northern Hemisphere tilts away from sun)
September equinox 30

31. 34.5 Regional climate influences the distribution of terrestrial communities
The tropics are the region surrounding the equator between latitudes 23.5° north and 23.5° south.
Uneven heating of the Earth causes rain and winds.
The direct intense solar radiation in the tropics near the equator has an impact on the global patterns of rainfall and winds.
The tropics experience the greatest annual input and least seasonal variation in solar radiation.
Student Misconceptions and Concerns
Students may confuse the terms ecology and environmentalism. The science of ecology and the environmental issues that it often raises are related but distinct processes.
Teaching Tips
Module 34.5 discusses the reasons why Earth’s tilt causes seasons. Consider challenging your students, perhaps as a short in-class activity, to explain why it is typically cooler (a) further away from the equator and (b) during the winter months. Although you may not want to use class time on this activity every year, collecting student responses before your students read or learn about this in class can reveal misconceptions and areas of misunderstanding that will help direct your teaching for years to come.
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32. Ascending moist air releases moisture
Figure 34.5C
Descending dry air absorbs moisture
Descending dry air absorbs moisture
Ascending moist air releases moisture
Trade winds
Trade winds
Figure 34.5C How uneven heating causes rain and winds
Doldrums
23.5 0
23.5
30
30
Temperate zone
Tropics
Temperate zone 32

33. 34.5 Regional climate influences the distribution of terrestrial communities
As the air rises in the tropics, it
cools and releases much of its water content,
produces the abundant precipitation typical of most tropical regions, and
creates an area of calm or very light winds known as the doldrums.
High altitude air masses
lose their moisture over equatorial zones and then
spread away from the equator.
Student Misconceptions and Concerns
Students may confuse the terms ecology and environmentalism. The science of ecology and the environmental issues that it often raises are related but distinct processes.
Teaching Tips
Module 34.5 discusses the reasons why Earth’s tilt causes seasons. Consider challenging your students, perhaps as a short in-class activity, to explain why it is typically cooler (a) further away from the equator and (b) during the winter months. Although you may not want to use class time on this activity every year, collecting student responses before your students read or learn about this in class can reveal misconceptions and areas of misunderstanding that will help direct your teaching for years to come.
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34. 34.5 Regional climate influences the distribution of terrestrial communities
The air then
cools and descends again at latitudes of about 30° north and south and
spreads back toward the equator creating the cooling trade winds that dominate the tropics.
As the air moves back toward the equator, it
warms and
picks up moisture.
Student Misconceptions and Concerns
Students may confuse the terms ecology and environmentalism. The science of ecology and the environmental issues that it often raises are related but distinct processes.
Teaching Tips
Module 34.5 discusses the reasons why Earth’s tilt causes seasons. Consider challenging your students, perhaps as a short in-class activity, to explain why it is typically cooler (a) further away from the equator and (b) during the winter months. Although you may not want to use class time on this activity every year, collecting student responses before your students read or learn about this in class can reveal misconceptions and areas of misunderstanding that will help direct your teaching for years to come.
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35. 34.5 Regional climate influences the distribution of terrestrial communities
The temperate zones are between the tropics and
the Arctic Circle in the north and
the Antarctic Circle in the south.
The temperate zones have seasonal variations and more moderate temperatures than the tropics or the polar zones.
Student Misconceptions and Concerns
Students may confuse the terms ecology and environmentalism. The science of ecology and the environmental issues that it often raises are related but distinct processes.
Teaching Tips
Module 34.5 discusses the reasons why Earth’s tilt causes seasons. Consider challenging your students, perhaps as a short in-class activity, to explain why it is typically cooler (a) further away from the equator and (b) during the winter months. Although you may not want to use class time on this activity every year, collecting student responses before your students read or learn about this in class can reveal misconceptions and areas of misunderstanding that will help direct your teaching for years to come.
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36. 34.5 Regional climate influences the distribution of terrestrial communities
Prevailing wind patterns result from the combined effects of
rising and falling air masses and
Earth’s rotation.
In the tropics, Earth’s rapidly moving surface deflects vertically circulating air, making the trade winds blow from east to west.
In temperate zones, the slower-moving surface produces the westerlies, winds that blow from west to east.
Student Misconceptions and Concerns
Students may confuse the terms ecology and environmentalism. The science of ecology and the environmental issues that it often raises are related but distinct processes.
Teaching Tips
Module 34.5 discusses the reasons why Earth’s tilt causes seasons. Consider challenging your students, perhaps as a short in-class activity, to explain why it is typically cooler (a) further away from the equator and (b) during the winter months. Although you may not want to use class time on this activity every year, collecting student responses before your students read or learn about this in class can reveal misconceptions and areas of misunderstanding that will help direct your teaching for years to come.
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37. 60N 30N 30S 60S Westerlies Trade winds Doldrums Trade winds
Figure 34.5D
60N
Westerlies
30N
Trade winds
Doldrums
Figure 34.5D Prevailing wind patterns
Trade winds
Westerlies
30S
60S 37

38. 34.5 Regional climate influences the distribution of terrestrial communities
Ocean currents, river-like flow patterns in the oceans, result from a combination of
prevailing winds,
the planet’s rotation,
unequal heating of surface waters, and
the location and shapes of the continents.
Ocean currents have a profound effect on regional climates.
Student Misconceptions and Concerns
Students may confuse the terms ecology and environmentalism. The science of ecology and the environmental issues that it often raises are related but distinct processes.
Teaching Tips
Module 34.5 discusses the reasons why Earth’s tilt causes seasons. Consider challenging your students, perhaps as a short in-class activity, to explain why it is typically cooler (a) further away from the equator and (b) during the winter months. Although you may not want to use class time on this activity every year, collecting student responses before your students read or learn about this in class can reveal misconceptions and areas of misunderstanding that will help direct your teaching for years to come.
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39. Greenland Europe North America Gulf Stream Africa South America
Figure 34.5E
Greenland
Europe
North America
Gulf Stream
Africa
ATLANTIC
OCEAN
Figure 34.5E Atlantic Ocean currents (red arrows indicate warming currents; blue arrows indicate cooling currents)
South America
PACIFIC OCEAN 39

40. 34.5 Regional climate influences the distribution of terrestrial communities
Landforms can also affect local climate. For example, air temperature declines about 6°C with every 1,000-m increase in elevation.
Near mountains, rainfall is affected by
location of mountains,
prevailing winds, and
ocean current patterns.
Student Misconceptions and Concerns
Students may confuse the terms ecology and environmentalism. The science of ecology and the environmental issues that it often raises are related but distinct processes.
Teaching Tips
Module 34.5 discusses the reasons why Earth’s tilt causes seasons. Consider challenging your students, perhaps as a short in-class activity, to explain why it is typically cooler (a) further away from the equator and (b) during the winter months. Although you may not want to use class time on this activity every year, collecting student responses before your students read or learn about this in class can reveal misconceptions and areas of misunderstanding that will help direct your teaching for years to come.
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41. Wind direction East Rain shadow Desert Sierra Nevada Coast Range
Figure 34.5F
Wind direction
East
Pacific Ocean
Rain shadow Desert
Sierra Nevada
Figure 34.5F How mountains affect precipitation (California)
Coast Range 41

42. 34.5 Regional climate influences the distribution of terrestrial communities
Climate and other abiotic factors of the environment control the global distribution of organisms.
The influence of these abiotic factors results in biomes, the major types of ecological associations that occupy broad geographic regions of land or water.
Student Misconceptions and Concerns
Students may confuse the terms ecology and environmentalism. The science of ecology and the environmental issues that it often raises are related but distinct processes.
Teaching Tips
Module 34.5 discusses the reasons why Earth’s tilt causes seasons. Consider challenging your students, perhaps as a short in-class activity, to explain why it is typically cooler (a) further away from the equator and (b) during the winter months. Although you may not want to use class time on this activity every year, collecting student responses before your students read or learn about this in class can reveal misconceptions and areas of misunderstanding that will help direct your teaching for years to come.
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43. AQUATIC BIOMES
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44. 34.6 Sunlight and substrate are key factors in the distribution of marine organisms
Aquatic biomes are shaped by the availability of
light and
nutrients.
Student Misconceptions and Concerns
Students may benefit from a review of the general properties of water introduced in Modules 2.10–2.16, which provide insight into the abiotic properties of aquatic biomes.
Teaching Tips
1. Before addressing aquatic biomes, consider asking your students to explain (a) why fog frequently forms over large bodies of water in the spring and fall and (b) how life would be different in aquatic environments if ice sank when it froze.
2. Consider exploring with your students the many ways that the Gulf of Mexico was impacted by the BP 2010 spill and the natural mechanisms in this biome that are helping it to recover.
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45. Benthic realm (seafloor from continental shelf to deep-sea bottom)
Figure 34.6A
High tide
Low tide
Pelagic realm (open water)
Oarweed (to 2 m)
Man-of-war (to 50 m long)
Turtle (60180 cm)
Sea star (to 33 cm)
Brain coral (to 1.8 m)
Photic zone
Phytoplankton
Zooplankton
Blue shark (to 2 m)
200 m
Intertidal zone
Continental shelf
Sponges (1 cm1 m)
Sperm whale (1020 m)
“Twilight”
Sea pen (to 45 cm)
Octopus
(to 10 m)
Hatchet fish (260 cm)
Aphotic zone
Benthic realm (seafloor from continental shelf to deep-sea bottom)
Sea spider
(190 cm)
Gulper eel (to 180 cm)
1,000 m
Rat-tail fish (to 80 cm)
Figure 34.6A Ocean life (zone depths and organisms not drawn to scale)
Angler fish (45 cm2 m)
No light
Brittle star (to 60 cm)
Glass sponge
(to 1.8 m)
Sea cucumber (to 40 cm)
Tripod fish
(to 30 cm)
6,000 10,000 m 45

46. Benthic realm (seafloor from continental shelf to deep-sea bottom)
Figure 34.6A_1
High tide
Low tide
Pelagic realm (open water)
Oarweed (to 2 m)
Sea star (to 33 cm)
Brain coral (to 1.8 m)
Photic zone
Phytoplankton
Zooplankton
200 m
Intertidal zone
Continental shelf
Sponges (1 cm1 m)
“Twilight”
Sea pen (to 45 cm)
Aphotic zone
Figure 34.6A_1 Ocean life (zone depths and organisms not drawn to scale) (part 1)
Benthic realm (seafloor from continental shelf to deep-sea bottom)
Sea spider
(190 cm)
1,000 m
No light
Brittle star (to 60 cm)
6,000 10,000 m 46

47. Pelagic realm (open water)
Figure 34.6A_2
Pelagic realm (open water)
Man-of-war (to 50 m long)
Turtle (60180 cm)
Photic zone
Zooplankton
Blue shark (to 2 m)
200 m
Sperm whale (1020 m)
“Twilight”
Octopus
(to 10 m)
Hatchet fish (260 cm)
Aphotic zone
Gulper eel (to 180 cm)
1,000 m
Figure 34.6A_2 Ocean life (zone depths and organisms not drawn to scale) (part 2)
Rat-tail fish (to 80 cm)
Angler fish (45 cm2 m)
No light
Glass sponge
(to 1.8 m)
Sea cucumber (to 40 cm)
Tripod fish
(to 30 cm)
6,000 10,000 m 47

48. 34.6 Sunlight and substrate are key factors in the distribution of marine organisms
Within the oceans are the
pelagic realm, which includes all open water,
benthic realm, which consists of the seafloor,
aphotic zone, where there is insufficient light for photosynthesis, and
photic zone, where light penetration is sufficient for photosynthesis and phytoplankton can occur.
Zooplankton are abundant in the pelagic photic zone.
Coral reefs also occur in the photic zone.
Student Misconceptions and Concerns
Students may benefit from a review of the general properties of water introduced in Modules 2.10–2.16, which provide insight into the abiotic properties of aquatic biomes.
Teaching Tips
1. Before addressing aquatic biomes, consider asking your students to explain (a) why fog frequently forms over large bodies of water in the spring and fall and (b) how life would be different in aquatic environments if ice sank when it froze.
2. Consider exploring with your students the many ways that the Gulf of Mexico was impacted by the BP 2010 spill and the natural mechanisms in this biome that are helping it to recover.
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49. Figure 34.6B
Figure 34.6B A coral reef with its immense variety of invertebrates and fishes 49

50. Figure 34.6C
Figure 34.6C An angler fish 50

51. 34.6 Sunlight and substrate are key factors in the distribution of marine organisms
The marine environment includes distinctive biomes where the ocean meets the land or fresh water.
Intertidal zones are where the ocean meets the land and the shore is
pounded by waves during high tide and
exposed to the sun and drying winds during low tide.
Estuaries are productive areas where rivers meet the ocean.
Wetlands are transitional between aquatic and terrestrial ecosystems.
Student Misconceptions and Concerns
Students may benefit from a review of the general properties of water introduced in Modules 2.10–2.16, which provide insight into the abiotic properties of aquatic biomes.
Teaching Tips
1. Before addressing aquatic biomes, consider asking your students to explain (a) why fog frequently forms over large bodies of water in the spring and fall and (b) how life would be different in aquatic environments if ice sank when it froze.
2. Consider exploring with your students the many ways that the Gulf of Mexico was impacted by the BP 2010 spill and the natural mechanisms in this biome that are helping it to recover.
© 2012 Pearson Education, Inc. 51

52. Figure 34.6D
Figure 34.6D An estuary in Georgia 52