Ecology and
Ecosystems
Definitions to get started
Essential Questions
1. Explain the two factors that interact in the
study of Ecology.
2. Describe an ecosystem and the 3 specific
parts that make up the areas of an
ecosystem.
3. Describe what limits where organisms can
live.
Ecology
� The science that studies how organisms relate to each other and their environment.
The study of Ecology
� The relationships and interactions of organisms & their environment. � Specifically - abiotic and biotic
� Biotic = living factors
� Abiotic = nonliving factors� temperature, wind, pH, currents,
minerals, salinity, and sunlight.
� Goal: To understand how, through relationships and interactions, changes will affect organisms in the environment.
Ecosystem
� Def: A community of interacting organisms through which energy is transferred.
� distinct entity
� clearly defined physical boundaries
� distinct abiotic conditions
� an energy source
� Examples:
� Estuary and Intertidal
Community
� Def: A collection of different organisms living and interacting in an ecosystem.
� This includes all species and types of organisms.
� Plants, animals, bacteria,
protists, fungi
� Estuaries have:
� Mudflats, Mangrove forest
� Intertidal has:
� Rocky shore, kelp forest
Population
� Def: A group of the same species living and interacting within a community.
� Interaction is key� sometimes two
populations of the same
species live in a single
community.
� Orcas in Puget Sound
Habitat
� Def: The area and conditions in
which you find an organism.
� Some species are adapted to
or occur in very specific
habitats, whereas others range
over a variety of habitats.
� Microhabitat - very small scale
� Tiny crustaceans and worms live
in the spaces between sand grains
� Meiofauna
Niche
� Def: An organism’s role in its habitat
� Very different species can occupy the same niche. � Coral reefs - cleaner-shrimp
and cleaner fish both survive by feeding on the parasites and dead or injured skin of reef fish.
� Habitat = organism’s address
� Niche = job
Energy Flow� Determines how much
energy is available for
organisms at higher trophic
levels.
� Primary producers shape
ecosystem.
� High primary production= � potential for more organisms
at high trophic levels
� And/or more trophic levels.
� Energy flows through an ecosystem, eventually being lost as heat into the water, atmosphere, and space.
Base Nutrient Cycle
� Nutrients aren’t ever lost.
� Crucial elements cycle
through ecosystems
� Carbon cycle is the basis for
most biomass in ecosystems
� Nutrients are limiting
� Energy usually not
� *The most highly productive
marine ecosystems are
found in colder water
***Most limited Nutrient Cycle
� Nitrogen cycle is more limited in marine ecosystems than terrestrial
� Inorganic N2 must be fixed into organic compounds before it can be used
� N2-fixing bacteria live primarily in terrestrial ecosystems.
� To get N2 into ocean –
� Seabird droppings,
erosion, and runoff
Nutrient Cycles are more important
than Energy
� Tropical ecosystems have more energy (sun) available
� oceanic conditions = less nutrients in tropical regions� Upwelling rare
� Temperate coastal waters = less overall sunlight
� receive far more nutrients.
� *The most highly productive marine ecosystems are found in colder water.
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