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Fundamentals of Ecology
Chapter 2 Fundamentals of Ecology Karleskint Turner Small
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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 (non-living, physical) 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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Key Concepts All organisms expend energy to maintain homeostasis, i.e., internal balance relative to external changes. Physical factors of the environment, such as sunlight, temperature, salinity, exposure, and pressure, will determine where organisms can live. Species interactions that influence the distribution of organisms in the marine environment include competition, predation and symbiosis.
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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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Key Concepts The average amount of energy passed from one trophic level to the next is approximately 10%, limiting 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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Study of Ecology Ecology Environment Habitat: where an organisms lives
Ecology from the Greek word oikos meaning “home” Environment biotic factors abiotic factors Habitat: where an organisms lives Ecosystems composed of living organisms and their non-living environment
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Figure 2-1 THE CORAL REEF HABITAT.
Pls note: In chapter 1, figure numbers were separated by a period and not a dash, e.g., Figure 2.1
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Study of Ecology The study of organisms interacting with one another and their environment. This entails: biological (biotic) factors environmental (abiotic) factors the organism’s behavior Niche: an organism’s environmental role
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Figure 2-12 A NICHE.
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Size of sediment particles
Higher Zone of overlap Niche Species B Niche Coarser Species B Salinity Size of sediment particles Larger Food size Stepped Art Fig. 2-12, p. 26
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Homeostasis and Distribution of Marine Organisms
Maintaining homeostasis changes in external environment internal adjustments to maintain a stable internal environment optimal range zones of intolerance
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Figure 2-2 OPTIMAL RANGE.
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Characteristics of the Physical Environment that Affect Organism Distribution
Sunlight photosynthesis vision desiccation Temperature ectotherms endotherms
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Characteristics of the Physical Environment that 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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Figure 2-4 OSMOSIS.
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Cell membrane Cell membrane Cell membrane
Inside the cell Outside Cell membrane Outside the cell Inside Cell membrane Outside the cell Inside Cell membrane No net water movement Net water movement out of the cell Net water movement into the cell (a) Isotonic solution (b) Hypertonic solution (c) Hypotonic solution Stepped Art Fig. 2-4, p. 19
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Characteristics of the Physical Environment that 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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Figure 2-5 PRESSURE.
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Metabolic requirements
Characteristics of the Physical Environment that 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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Populations A group of the same species that occupies a specified area
A group of the same species that occupies a specified area Geographic range Population size
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Distribution of Organisms in a Population
Distribution of Organisms in a Population Population density (abundance) Dispersion clumped uniform random
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Changes in Population Size
Can occur through: reproduction immigration death emigration Can be affected by: survivorship life history opportunistic and equilibrium species
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Population Growth Many ways a population can increase in size, depending on the carrying capacity of the environment exponential/logarithmic growth logistic growth
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Figure 2-10 POPULATION GROWTH.
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Population Growth Density Dependent Factors
Density Dependent Factors have greater effect as population increases in size Density Independent Factors not related to population size
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Communities Composed of populations of different species that occupy one habitat at the same time Niche: what an organism does in its environment fundamental niche realized niche
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Communities Biological environment competition
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
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Communities Symbiosis: living together
Symbiosis: living together mutualism – both organisms benefit commensalism – one organism benefits, the other is nether harmed nor benefited parasitism – one organism benefits, the other is harmed
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Ecosystems: Basic Units of the Biosphere
Energy flow through ecosystems Producers = Autotrophs (auto = self, troph = feed) photosynthetic producers chemosynthetic producers
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Figure 2-16 PHOTOSYNTHESIS.
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6 Carbon dioxide (CO2) 6 Water (H2O) 6 Oxygen (O2) Glucose (C6H12O6)
Sunlight Chlorophyll 6 Carbon dioxide (CO2) 6 Water (H2O) + 6 Oxygen (O2) + Glucose (C6H12O6) Produces Stepped Art Fig. 2-16, p. 32
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Ecosystems: Basic Units of the Biosphere
Measuring primary productivity rate at which energy-rich food molecules are being produced from inorganic matter measuring carbon in organic products of photosynthesis light-dark-bottle method radioactive tracers satellite images
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Ecosystems: Basic Units of the Biosphere
Consumers = Heterotrophs (hetero = other, troph = feed) 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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Figure 2-17 A FOOD CHAIN.
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(third-order consumer, carnivore) Seaweed (producer) Helmet snail
Fish (third-order consumer, carnivore) Seaweed (producer) Helmet snail (second-order consumer, carnivore) Sea urchin (first-order consumer, herbivore) Stepped Art Fig. 2-17, p. 33
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Figure 2-18 A FOOD WEB.
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Ecosystems: Basic Units of the Biosphere
Trophic levels number of levels 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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Figure 2-19 (a) ECOLOGICAL EFFICIENCY.
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Figure 2-19 (b) ECOLOGICAL EFFICIENCY.
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Biogeochemical Cycles
Hydrologic cycle water is lost through evaporation carried north and south from equator carried west to east within each hemisphere returned through precipitation and runoff
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Figure 2-20 THE HYDROLOGIC CYCLE.
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rivers, soils, vegetation, lakes, falling precipitation
Moist air Evaporation from rivers, soils, vegetation, lakes, falling precipitation Evaporation from ocean Salt Runoff Soak in and percolation Sea spray Soil moisture Lakes Groundwater Seepage Ocean Land Stepped Art Fig. 2-20, p. 36
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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 fossil fuels when burned release CO2 back into atmosphere
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Figure 2-21 THE CARBON CYCLE.
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CO2 in atmosphere to plants for photosynthesis CO2 in the atmosphere
Dissolved CO2 forms HCO3– CO2 is taken up by phytoplankton for photosynthesis Precipitation Limestone Sediments Respiration Dissolved CO2 Decomposers Decomposition Peat coal Plant residues Shells Limestone Stepped Art Fig. 2-21, p. 37
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Biogeochemical Cycles
Nitrogen cycle producers use nitrogen to synthesize protein forming amino acids bacteria recycle nitrogen from wastes and decomposing, dead organisms fixation of atmospheric nitrogen by microorganisms
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Figure 2-22 THE NITROGEN CYCLE.
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Biosphere Includes all of earth’s communities and ecosystems
Examples of ecosystems: estuaries salt marshes mangrove swamps rocky and sandy shores kelp forests coral reefs open ocean
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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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