Eutrophication & Dead ZonesANSWER KEY
Name: Period: Date:
1.Multiple sources contribute; CO2 is primary but not sole cause
2.Excess nutrients cause eutrophication and dead zones
3.Eutrophication cascade: Excess nutrients from fertilizer runoff trigger massive algae blooms; when the algae die, decomposers consume dissolved oxygen, creating hypoxic dead zones where fish and other organisms suffocate and die.
[!] STUDY GUIDE: Big Ideas Use to answer form questions!
1.Too much of a "good thing" can be deadly. Excess nitrogen/phosphorus trigger cascades that kill ecosystems.
2.Eutrophication is a positive feedback loop. More nutrients lead to more algae, more decomposition, and less oxygen.
3.Atoms don't disappear—they travel. Nitrogen from Midwest farms ends up in Gulf dead zones.
Nutrients -> Algae Blooms -> Algae Dies -> Bacteria Decompose -> O2 Gone -> DEAD ZONE
EUTROPHICATION CASCADE (Use mass conservation from W1!)
[#] KEY TERMS Define in YOUR words
Eutrophication
Excessive nutrient enrichment that causes algae blooms
Nutrient
N or P needed for growth
Algae bloom
Rapid algae population explosion
Dead zone
An area with too little oxygen for marine life
[?] THE PHENOMENON Write BEFORE Hook form
What happens when nutrients run off into waterways?
In 2014, Toledo, Ohio's water became unsafe. 500,000 people couldn't use tap water for 3 days—a massive algae bloom in Lake Erie fed by agricultural runoff.
Your initial thinking:
[>] AFTER HOOK FORM Reflect, then continue +2 pts
I learned that...
Station 1 — Nutrient Cycle
Nutrients enter water from...
Excess nutrients cause...
Key insight:
Station 2 — Dead Zone Data
The data shows that...
Dead zones are worst when...
Key insight:
[/] DAY 1 EXIT TICKET Complete before leaving +5 pts
Q1:
If farmers doubled fertilizer use, what happens to the Gulf dead zone? Trace the cascade.
Q2:
Order (1-4): ___ Fish die | ___ Algae grows | ___ Bacteria use O2 | ___ Nutrients enter water
Confidence:
NGSS: MS-ESS3-3 Page 1 of 2 | Day 1 v3.5
Eutrophication & Dead Zones (continued)ANSWER KEY
Name:
[=] Day 2 start
Station 3 — Solutions & Prevention
One solution to reduce runoff is...
This works because...
A tradeoff or challenge is...
Key insight:
[+] MAKING CONNECTIONS Use for Exit Ticket!
Compare eutrophication to ocean acidification (W1). Both are human-caused—how do they differ?
How is eutrophication like Cycle 3 feedback loops? Does it amplify or stabilize?
[/] DAY 2 EXIT TICKET Final check before Science Circle +5 pts
Q1 (NEW):
Trace: nutrients -> algae -> O2 depletion. Explain why adding nutrients reduces O2.
Q2 (SPIRAL):
Both acidification and eutrophication are human-caused—how do their ecosystem impacts differ?
Q3 (INTEGRATION):
How is eutrophication like Cycle 3 feedback loops? Explain the self-amplifying nature.
CHECK TEST YOUR THINKING Rate each: FALSE ← 1–2–3–4–5 → TRUE
1. Adding more nutrients to a lake always makes the ecosystem healthier because plants grow faster.
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2. Dead zones form because algae blooms use up all the oxygen in the water directly through their own respiration.
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3. Fertilizer runoff from farms hundreds of miles away can cause dead zones in the ocean at river mouths.
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4. Once a dead zone forms, it is permanent and the ecosystem can never recover.
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5. Algae blooms only happen in freshwater lakes and rivers, not in the ocean.
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Pick any TWO statements — especially any you rated 2, 3, or 4. Justify your rating with evidence:
Statement #___ — I rated it ___ because:
Statement #___ — I rated it ___ because:
[O] SCIENCE CIRCLE ~15 min | End of week +3 pts
[!] My "Aha!" Moment
[?] My Remaining Question
Discussion Protocol: Share ahas, listen actively, record class discoveries.
CLASS DISCOVERIES
1.
2.
[X] We used to think:
[OK] Now we understand:
[*] Something challenging I tried:
NGSS: MS-ESS3-3 Page 2 of 2 | Day 2 v3.5