Ecosystem Energy Flow

Overview

This lecture covers how energy and matter flow through ecosystems, focusing on food chains, food webs, and trophic levels.

Ecosystems need a constant energy input, mostly from sunlight or chemical compounds.
Producers (autotrophs) make their own food using sunlight (photosynthesis) or chemicals (chemosynthesis).
Photoautotrophs use sunlight (plants, algae, some bacteria); chemoautotrophs use inorganic chemicals (some bacteria, archaea).
Consumers (heterotrophs) get energy by eating other organisms.

Herbivores eat only producers (plants).
Carnivores eat other animals (meat).
Omnivores eat both producers and other consumers.
Detritivores consume decomposing matter and feces (include scavengers and decomposers).
Scavengers eat dead animals; decomposers (like fungi, bacteria) break down dead material and recycle nutrients.
Saprotrophs feed on remaining organic matter after decomposers act.

Food chains show direct feeding relationships and energy flow in one direction.
Arrows in food chains/webs point from food to eater.
Simple food chains are rare; food webs illustrate complex, interconnected feeding relationships.
Energy can transfer between ecosystems when organisms from one ecosystem consume those from another.

Trophic levels are feeding positions: producers at the base, various consumers above.
Only about 10% of energy moves from one trophic level to the next; the rest is lost (mainly as heat).
Energy pyramids show this decrease, with fewer, larger organisms at higher levels.
Biomass (total mass at each level) also decreases as you move up the trophic pyramid.
Most food chains have a maximum of four trophic levels due to energy loss.

Producer (Autotroph) — Organism that makes its own food from sunlight or chemicals.
Consumer (Heterotroph) — Organism that eats others for energy.
Photoautotroph — Organism that uses sunlight to make food.
Chemoautotroph — Organism that uses chemical compounds for energy.
Herbivore — Consumer that eats only plants.
Carnivore — Consumer that eats only animals.
Omnivore — Consumer that eats both plants and animals.
Detritivore — Organism that feeds on dead matter and waste.
Scavenger — Detritivore that eats dead animals.
Decomposer — Organism that breaks down dead matter, recycling nutrients.
Saprotroph — Organism that feeds on organic matter after other decomposers.
Trophic Level — Position an organism occupies in a food chain/web.
Biomass — Total mass of organisms at a trophic level.

Review or create diagrams of energy flow (food chains, webs, ecological pyramids).
Study key terms and their roles in ecosystem energy transfer.