Human Impacts Study Guide — Simplified Notes

Human Impacts Study Guide — Simplified Notes

1. Plastic Pollution

• Comes from human trash (bags, bottles, straws, etc.) that ends up in rivers, beaches, and oceans.

• Found everywhere, even deep sea and Arctic.

2. How Plastics Harm Animals

• Animals eat plastic by mistake or get tangled.

• Bags, bottle caps, fishing lines cause most harm.

3. Microplastics

• Tiny pieces of broken-down plastic.

• Get in the ocean from litter, laundry, and broken plastic.

• Hard to clean because they’re small and float everywhere.

4. Sea Turtles & Plastic Bags

• Turtles think bags look like jellyfish (their favorite food) and eat them.

• Birds eat plastic bottle caps, straws, and small plastic bits.

• Plastic fills the stomach, so birds starve even though they “feel full.”

5. Biomagnification

• Toxins build up as you move up the food chain.

• Top predators (sharks, whales, humans) get the most poison from polluted food.

6. Runoff

• Water from rain or melting snow washes dirt, oil, trash, fertilizer, and chemicals into oceans.

• Pollutes water and can cause harmful algal blooms.

7. Eutrophication

• Too many nutrients (fertilizer) cause too much algae to grow.

• When algae die, bacteria eat them and use up all the oxygen — causing hypoxia or dead zones.

8. Dead Zone vs. Toxic Algal Bloom

• Dead Zone: water with no oxygen, no life.

• Toxic Algal Bloom: algae release poisons that harm animals.

• Red Tide is a type of toxic algal bloom.

9. Nutrient Levels

• Too many nutrients = more harmful algae.

• Dead algae = hypoxia (low oxygen) = dead zone.

10. Sewage & Eutrophication

• Sewage carries nutrients like nitrogen.

• Leads to algae blooms and hypoxia.

11. Dead Zones Location

• Near coasts, especially where rivers bring farm runoff into the ocean (example: Gulf of Mexico).

12. Things Humans Get from the Ocean

• Food, oxygen, recreation, medicine, jobs.

13. Three Main Types of Pollution

• Plastic, chemical, and oil.

14. Four Ways Humans Harm Oceans

• Pollution, overfishing, habitat destruction, climate change.

15. Human Activities Causing Marine Pollution

• Littering, farming runoff, sewage, oil spills, burning fossil fuels.

16. Marine Protected Areas (MPAs)

• Protected ocean zones where human activities are limited.

• Help stop overfishing, pollution, and habitat destruction.

17. Stakeholders in MPAs

• People (fishermen, scientists, local communities) who help make rules for the protected areas.

18. Ghost Fishing

• Lost or abandoned fishing gear that still traps and kills marine animals.

19. Bycatch

• Animals caught by accident (turtles, dolphins).

• Caused by nets, trawls, and longlines.

20. Six Destructive Fishing Methods

• Trawling: dragging nets along the seafloor.

• Longlines: long fishing lines with lots of hooks.

• Gill Nets: trap fish by their gills.

• Purse Seines: large nets close around fish.

• Dynamite Fishing: using explosives to kill fish.

• Cyanide Fishing: poison used to stun fish.

21. Fishing Methods that Damage Habitats

• Trawling damages the seafloor and coral reefs.

22. Other Human Actions that Damage Habitats

• Coastal construction, pollution, oil drilling.

23. Fossil Fuels & Coral Bleaching

• Burning fuels releases CO2 (greenhouse gas).

• CO2 warms ocean and makes it more acidic — both cause coral bleaching.

24. Destructive Fishing & Coral

• Trawling and dynamite fishing break coral structures.

25. Greenhouse Gas Emissions

• Gases from cars, factories, and power plants trap heat, causing global warming.

26. Coastal Urbanization

• Building towns and cities near the coast.

• Leads to more pollution, habitat loss, and runoff.