Chapter 2 9
2
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FUNDAMENTALS OF
ECOLOGY
Chapter Outline
THE STUDY OF ECOLOGY
ECOLOGY AND THE PHYSICAL
ENVIRONMENT
The Environment
Habitat: Where an Organism Lives
Maintaining Homeostasis
POPULATIONS
Population range and size
Distribution of Organisms in a
Population
Changes in Population Size
Survivorship
Life History
Biological Interactions
Competition
Predator-Prey Relationships
Symbiosis: Living Together
ECOSYSTEMS: BASIC UNITS OF THE
BIOSPHERE
Hydrologic Cycle
Carbon Cycle
Nitrogen Cycle
THE BIOSPHERE
Distribution of Marine Communities
and Ecosystems
Pelagic Division
10 Fundamentals of Ecology
Chapter Objectives
• Recognize the scope and scale of ecology as it pertains to marine environments.
• Identify the abiotic factors that constrain marine organisms.
• Define population.
• Explain the different measurements of populations that scientists use and what
those measurements tell scientists.
Key Terms
ecosystem
biosphere
environment
stress zone
zone of tolerance
phytoplankton
desiccant
ectotherms
endotherms
algal bloom
population
geographic range
random pattern
generation time
survivorship
survivorship curve
Type I survivorship
curve
exponential growth
logistic growth
carrying capacity
community
niche
fundamental niche
realized niche
interspecific
competition
commensalism
parasitism
parasite
host
consumers
second-order
(secondary)
consumers
third-order (tertiary)
consumers
omnivores
detritivores
detritus
decomposers
energy pyramid
pyramid of biomass
pyramid of numbers
biogeochemical cycle
precipitation nuclei
pelagic division
water column
benthic division
neritic province
oceanic province
shelf zone
bathyal zone
abyssal zone
hadal zone
epifauna
infauna
Chapter Summary
1. An organism’s environment consists of all the external factors acting on that
2. In ecological terms, a population is a group of the same species that occupies a
specific area. Factors that affect reproduction and mortality rate, such as
3. A community is composed of populations of organisms that occupy the same habitat
4. Although energy constantly flows through ecosystems, nutrients necessary for life
are constantly recycled. Producers capture the energy of sunlight in the chemical
bonds of organic molecules. Consumer organisms rely on these molecules as a
12 Fundamentals of Ecology
5. The biosphere contains all of the Earth’s communities and ecosystems. Estuaries,
rocky coasts, sandy shores, salt marshes, mangrove swamps, kelp forests, and coral
Chapter Outline
I. Study of Ecology
A. Ecology, ecosystems, and biospheres.
1. Energy flows through the ecosystems in the biosphere.
2. Nutrients cycle through biosphere ecosystems.
1. Abiotic factors.
a. Temperature.
b. Salinity.
2. Biotic factors.
B. Habitat: where an organism lives.
1. Marine habitats include (but are not limited to):
a. Rocky shores.
2. Marine habitats are unique and characterized by specific abiotic factors that define
their worldwide distribution.
3. Microhabitats: small subdivisions within a larger habitat.
C. Maintaining homeostasis.
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3. Homeostasis and the distribution of marine organisms.
a. Optimal range.
D. Characteristics of the abiotic environment.
1. Physical environment: Physical parameters of marine ecosystems determine the
biological communities found in the ecosystem.
2. Sunlight: The amount of sunlight in an ecosystem determines how much
photosynthetic activity (food production) occurs in that ecosystem.
3. Temperature: Surface water temperature varies less than ambient air
4. Salinity.
a. Solutes.
b. Osmosis.
c. Salt and water balance.
5. Water pressure: Water pressure increases one atmosphere (760 mm Hg) for every
10 meters of water depth.
6. Metabolic requirements: All organisms require nutrients to survive and grow.
a. Nutrients.
7. Metabolic wastes: All organisms produce waste as a result of metabolism.
III. Populations
A. Population range and size.
B. Population density.
1. Dispersion.
a. Uniform distribution.
C. Changes in population size.
1. Population size increases as a result of births (natality) and immigration (new
14 Fundamentals of Ecology
3. Survivorship: the relationship between age and mortality; this relationship is
frequently illustrated using a graph in which age is the independent variable (x–
axis) and population size is the dependent variable (y-axis).
4. Life history is divided into three phases: birth, reproduction, and death;
population size is a function of:
a. Age of first reproduction.
D. Population growth.
1. Continuous population growth without environmental limitations produces an
exponential growth curve.
4. Carrying capacity.
5. Population regulation.
IV. Communities
A. Niche.
1. Fundamental niche.
B. Biological interactions.
1. Competition.
a. Interspecific competition.
D. Symbiosis.
1. Mutualism.
2. Commensalism.
3. Parasitism.
V. Ecosystems: Basic Units of the Biosphere
A. Energy flows through an ecosystem.
1. Producers/autotrophs.
2. Photosynthesis.
9. Omnivores.
10. Detritivores.
11. Food chain and web.
12. Dissolved organic matter (DOM).
13. Trophic level.
B. Biogeochemical cycles: cycling of nutrients through trophic structures.
1. Hydrological cycle (water cycle).
VI. The Biosphere
A. Distribution of marine communities in the biosphere (refer to Figure 2-24).
B. Pelagic division.
1. Neritic zone.
2. Oceanic zone.
C. Benthic division.
1. Intertidal zone.
2. Bathyal zone.
16 Fundamentals of Ecology
Suggestions for Presenting the Material
1. This chapter is about interactions of organisms with one another and their
environment. Try handing out a list of challenge questions, such as a list of the
2. Video clips of species interactions from the Blue Planet and Planet Earth series
Classroom Discussion Ideas
1. In what ways do humans disrupt the nitrogen cycle? What are the impacts of these
disruptions?
Videos, Animations, and Websites
Videos
Ocean Adventures with Cousteau. (DVD, PBS, 2006)
The Blue Planet.
Well known for its stunning photography, this series also helps showcase the wide
Planet Earth.
The epitome of natural history documentaries, the episodes “Shallow Seas” and “Ocean
Chapter 2 17
Animations
The Hydrologic Cycle.
Nitrogen Cycle.
This animation details the nitrogen cycle.
The Carbon Cycle.
This animation details the carbon cycle.
Websites
EPA Marine Ecosystems.
University of California Museum of Paleontology.
An introduction to the major marine biomes.
United Nations Atlas of the Oceans.
United Nations Atlas of the Oceans.
18 Fundamentals of Ecology
Suggested Answers to End of Chapter Questions
Multiple Choice
1. e. higher salinity, coarse sediments, and smaller food
Matching
1. b.
6. c.
11. c.
Short Answer
1. What are six abiotic factors that affect the distribution of organisms in an ecosystem?
2. What would probably happen to the natural balance in a community if the population
of predators dramatically decreased or was wiped out?
If the population of predators dramatically decreased or disappeared, the
3. What is the difference between a community and an ecosystem?
The community is a group of organisms of differing species living together in a
4. Describe the three main types of symbiotic relationships found in nature.
The three types of symbiotic relationships that occur in nature are mutualism,
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5. Describe the marine nitrogen cycle.
Nitrogen enters the marine environment in one of two ways, as terrestrial run-off
6. Why are there fewer marine organisms in the ocean’s depths?
There are fewer organisms in the deep ocean because the biomass of the deep
7. Why are so many marine organisms ectotherms?
Since water has a high heat capacity, the temperature of the surface ocean varies
8. Why is energy transfer between trophic levels inefficient?
Trophic transfer of energy is inefficient because the majority of caloric intake
9. How can groups of similar species avoid competition?
Groups of similar species can avoid competition by resource partitioning—this
10. How can primary production be measured?
Primary production is estimated using the light and dark bottle method, and
estimating carbon fixation is done by measuring dissolved oxygen. Since oxygen is
20 Fundamentals of Ecology
11. Why can’t most populations continually grow at an exponential rate?
12. Describe a detritus-based food chain.
Detritus is dead, decaying organic matter. In the majority of deep ocean
13. Describe two methods that could be used to determine the size of a population in the
wild.
Population size can be estimated in one of two ways. The first method is to divide
the habitat into smaller subdivisions or plots and count all the organisms in a
14. What characteristics do you associate with an opportunistic species?
Opportunistic species tend to have relatively short life spans, reproduce early in
15. What is the difference between an organism’s fundamental niche and its realized
niche?
The fundamental niche is the broadest definition of the species niche, the resources
Thinking Critically
1. Does the area of overlap in Figure 2-12 indicate that species A and species B have
overlapping niches and will be in direct competition under those conditions? Why or
why not?
Figure 2-12 does indicate that species A and species B will be in direct competition
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2. Why does it make good ecological sense for whales to feed on plankton?
Because only 10 percent of the total energy available at one trophic level is
3. Although the open ocean receives plenty of radiant energy and has a larger area, it is
not nearly as productive as the shallow coastal seas. Why?
Open ocean productivity is nutrient-limited; limiting nutrients such as nitrogen
4. Why do organisms that live in tide pools have to be more tolerant of changes in
salinity than organisms that live in the open sea?
Organisms that live in tidal pools must be tolerant of changing salinities because
5. Which type of competition do you think would be more intense, interspecific or
intraspecific? Why?
Intraspecific competition (competition between two or more organisms of the same
6. Would it be possible to have a pyramid of numbers where the trophic level above is
larger than the trophic level below? Explain using an example with marine
organisms.
Examination of Figure 2-18 would suggest that there are fewer great whales than
22 Fundamentals of Ecology
7. Under what conditions would it be advantageous for a female to delay reproduction
until later in life?
All things being equal, larger females produce either more eggs (which equals
Suggested InfoTrac® Articles
“In Ocean’s Teeming Top Layer, Scientists Find a Microbe Haven.” (Science
Desk.) Zimmer, C. The New York Times, (July 28, 2009).
“Study Finds Shark Overfishing May Lower Scallop Population.” (National Desk)
Fountain, H. The New York Times, (March 30, 2007).