Comprehensive Study Notes on Ecosystem Dynamics, Trophic Levels, and Energy Flow
Core Ecosystem Definitions and Components
Ecosystem: A specific area where all non-living (abiotic) and living things (biotic) interact with one another. An example of an ecosystem is an ocean.
Organism: Any single living individual animal or plant. An example of an organism is a reef shark.
Population: A specific part of an ecosystem that consists of only one type of species. An example of a population is all rainbow fish within an area.
Community: A part of the ecosystem that consists of many different species living together. An example of a community includes triggerfish, moray eels, and sponges.
Habitat: The specific area or "home" where animals or plants live. An example of a habitat is a coral reef.
Biotic Factors: The living organisms within an ecosystem.
- BAPFA Mnemonic:
- B - Bacteria
- A - Animals
- P - Plants
- F - Fungus
- A - Algae
Abiotic Factors: The non-living components within an ecosystem.
- MR. STRAWS Mnemonic:
- M - Minerals
- R - Rocks
- S - Sun
- T - Temperature
- A - Air
- W - Water
- S - Soil
Trophic Roles: Producers, Consumers, and Decomposers
Producers: Organisms that manufacture their own food by capturing energy from the Sun through a biological process known as photosynthesis. Most producers are plants.
- Photosynthesis Chemical Reaction:
- Algae:
- Algae are special types of plants that act as producers.
- They live in water or on wet surfaces.
- They can be single-celled (microscopic) or quite large.
- They lack true roots, stems, or leaves.
- Seaweed, such as kelp, represents an example of large algae.
- Phytoplankton refers to microscopic algae.
Consumers: Any organism that cannot manufacture its own food and must obtain energy by consuming plants or other animals.
- Herbivores: Organisms that eat only plants.
- Examples: Deer, cows, rabbits, vegetarians.
- Carnivores: Meat-eating organisms that consume other animals.
- Examples: Lions, eagles, spiders.
- Omnivores: Organisms that eat both plants and animals ("omni" meaning all).
- Examples: Most humans, pigs, bears.
Predator and Prey Dynamic:
- Predator: An animal that actively hunts and kills other animals for food; it is a specialized type of consumer.
- Prey: An animal that is hunted and caught for food by a predator.
Decomposers: Organisms that acquire energy by breaking down nutrients found in dead plants, dead animals, or animal waste.
- Ecological Function & Importance:
- Prevent dead plant and animal matter or waste from accumulating in the environment.
- Return valuable materials (such as carbon dioxide or minerals) back to the soil, air, and water during the breakdown process.
- Recycled nutrients are subsequently absorbed by plants to produce food, sustaining the nutrient cycle throughout the ecosystem.
- Without decomposers returning these nutrients, organisms within the ecosystem could not survive for long.
- Examples: Bacteria, fungi (mushrooms and molds), termites, earthworms, and dung beetles.
Energy Flow in Ecosystems
Food Chain: A linear representation showing how energy is passed sequentially from one organism to the next.
Food Web: A complex, interconnected network of multiple food chains and feeding relationships within an ecosystem.
Energy Pyramid:
- Graphically illustrates the direction of energy flow through an ecosystem.
- The total amount of available energy decreases as the pyramid tapers toward the top.
- Divided into distinct trophic energy levels: primary, secondary, and tertiary levels.
Major Ecosystem Categories
Terrestrial Ecosystems: Land-based ecosystems.
- Examples: Deciduous forest, tropical rainforest, desert, tundra, prairie, savanna/grasslands.
Aquatic Ecosystems: Water-based ecosystems.
- Examples: Lake, pond, rivers, streams, marshes, estuaries, oceans.