1. Fundamentals of Ecology
Chapter 2
Fundamentals of Ecology
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2. Key Concepts
Ecology is the study of relationships among organisms and the interactions of organisms with their environment.
An organism’s environment consists of biotic (biological interactions) and abiotic (physical characteristics of the environment) factors.
An organism’s habitat is where it lives, and its niche is the role the organism plays in its community.
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3. Key Concepts All organisms expend energy to maintain homeostasis.
All organisms expend energy to maintain homeostasis.
Physical factors of the environment, such as sunlight, temperature, salinity, exposure, and pressure, will dictate where organisms can live.
Species interactions that influence the distribution of organisms in the marine environment include competition, predator-prey relationships, and symbiosis.
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4. Key Concepts
Marine ecosystems consist of interacting communities and their physical environments.
Most populations initially grow at an exponential rate, but as they approach the carrying capacity of the environment, the growth rate levels off.
Energy in ecosystems flows from producers to and through consumers.
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5. Key Concepts
The average amount of energy passed from one trophic level to the next is approximately 10%, and this ultimately regulates and limits the number and biomass of organisms at different trophic levels.
With the exception of energy, everything that is required for life is recycled.
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6. Study of Ecology Environment Habitat: where an organisms lives
Environment
biotic factors
abiotic factors
Habitat: where an organisms lives
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8. Study of Ecology Niche: an organism’s environmental role
Niche: an organism’s environmental role
environmental factors
biological factors
the organism’s behavior
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10. Environmental Factors Affect Organism Distribution
Maintaining homeostasis
changes in external environment
internal adjustments to maintain a stable internal environment
homeostasis and the distribution of marine organisms
optimal range
zones of intolerance
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12. Environmental Factors Affect Organism Distribution
Physical environment
sunlight
photosynthesis
vision
desiccation
temperature
ectotherms
endotherms
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13. Environmental Factors Affect Organism Distribution
salinity
solutes
osmosis
solutes in the body fluids of organisms
tolerance for variation ion environmental salinity
regulation of solutes in body fluids
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15. Environmental Factors Affect Organism Distribution
pressure
760 mm Hg or 1 atmosphere at sea level
increases 1 atmosphere for every 10 meters below sea level
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17. Environmental Factors Affect Organism Distribution
metabolic requirements
nutrients and limiting nutrients
oxygen as a requirement for metabolism
anaerobic and aerobic organisms
eutrophication and algal bloom
metabolic wastes
carbon dioxide is a common byproduct of metabolism
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18. Environmental Factors Affect Organism Distribution
Biological environment
competition
may be interspecific or intraspecific
may result in competitive exclusion
resource partitioning allows organisms to share a resource
predator-prey relationships
balance of abundance of prey vs. predators
keystone predators
boom-or-bust cycles result from imbalances
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19. Environmental Factors Affect Organism Distribution
symbiosis: living together
mutualism – both organisms benefit from the relationship
commensalism – one organism benefits, whereas the other is nether harmed nor benefited
parasitism – the parasite lives off the host; the parasite benefits while the host is harmed
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20. Populations and Communities
Population – a group of the same species that occupies a specified area
Community – composed of populations of different species that occupy one habitat at the same time
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21. Populations and Communities
Population growth
there are many ways in which a population can increase in size
e.g., recruitment
exponential growth
logistic growth
carrying capacity
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23. Populations and Communities
Distribution of marine communities
pelagic division
neritic zone and pelagic zone
photic zone, disphotic zone, and aphotic zone
plankton and nekton
benthic division
shelf zone, bathyal zone, abyssal zone, and hadal zone
epifauna and infauna
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25. Ecosystems: Basic Units of the Biosphere
Examples of ecosystems
estuaries
salt marshes
mangrove swamps
rocky shores
sandy beaches
kelp forests
coral reefs
open ocean
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26. Ecosystems: Basic Units of the Biosphere
Energy flow through ecosystems
Producers
photosynthetic producers
chemosynthetic producers
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28. Ecosystems: Basic Units of the Biosphere
Measuring primary productivity
rate at which energy-rich food molecules are being produced from inorganic matter
light-dark-bottle method
measuring carbon in organic products of photosynthesis
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29. Ecosystems: Basic Units of the Biosphere
Consumers
first-order consumers
second- and third-order consumers
detrivores
decomposers
Food chains and food webs
Other energy pathways
dissolved organic matter (DOM)
detritus
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32. Ecosystems: Basic Units of the Biosphere
Trophic levels
number is limited because only a fraction of the energy at one level passes to the next level
ecological efficiency
ten percent rule
trophic pyramids
as energy passed on decreases, so does the number of organisms that can be supported
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35. Biogeochemical Cycles
Hydrologic cycle
water is lost through evaporation
returned through precipitation and runoff
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37. Biogeochemical Cycles
Carbon cycle
carbon released from organisms through respiration and decomposition
recycled by photosynthetic producers
carbon is used in shells, corals and skeletons as part of calcium carbonate
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39. Biogeochemical Cycles
Nitrogen cycle
producers use nitrogen to synthesize proteins (amino acids)
bacteria recycle nitrogen from wastes and decomposing, dead organisms
fixation of atmospheric nitrogen by microorganisms
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