This lesson explores how energy moves through aquatic food chains and food webs, why efficiency limits the number of large predators, and how human actions (runoff, dams, overfishing, invasive species) disrupt these dynamics. It includes real-world examples, classroom activities, reflection questions, and practical takeaways emphasizing the importance of small organisms for ecosystem resilience.
Food Chain Dynamics in Aquatic Systems — The Food Web That Actually Cares About Who Eats Who
"Ecosystems are basically soap operas with algae: everybody is connected, and one dramatic plot twist (like pollution) ruins everyone's day." You already learned about Biodiversity in Water Systems and how Human Practices Impact Ecosystems can push species to the brink. You also studied how C...
What is a Food Chain (and why it’s not boring) Food chain: A simple line showing who eats whom — energy passing from one organism to the next. Food web: The messy, realistic version — lots of lines, lots of drama, lots of surprise cameos. Why it matters: Energy flow determines population siz...
Quick visual: a classic aquatic food chain Phytoplankton --> Zooplankton --> Small Fish --> Large Fish --> Seal/Seabird --> Orca Phytoplankton = the tiny green factories of the ocean and lakes. They photosynthesize, turning sunlight into energy that powers everything above them.
Energy Transfer: The Pyramid That Hates Efficiency Energy flows up trophic levels, but here’s the bummer: only ~10% of energy moves to the next level (give or take). The rest is lost as heat, used in life processes, or becomes poop (nature's blunt truth). Producers (phytoplankton, algae, aq...
Marine vs Freshwater Food Chains — Same Rules, Different Stage Feature Marine (Ocean) Freshwater (Lakes, Rivers) Primary producers Mainly phytoplankton, seaweed Phytoplankton, macrophytes (aquatic plants) Energy base Often vast but patchy (upwelling zones rich) Can be localized;...
Real-world Examples: How Food Chains React to Disturbance Eutrophication (nutrient runoff → algal blooms): Farms add nitrogen/phosphorus to rivers. Algae bloom, block sunlight, die, decompose. Decomposition uses oxygen — fish suffocate. Result: a collapse of higher trophic levels, less biodiversi...
Why Biodiversity Makes Food Webs More Resilient Remember: biodiversity means many species doing similar jobs. If one species disappears, others can step in. That redundancy is like having backups in case the lead singer gets sick. Diverse systems: more stable, better at resisting disease and re...
Classroom Thought-Exercises & Micro-Experiments Food Chain Role-play (5–10 minutes): Assign students roles (phytoplankton, zooplankton, small fish, big fish, bird). Run rounds where 'energy tokens' get passed with the 10% rule. Introduce a disturbance (remove big fish) and watch chaos...
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