1
What is a dead zone?
Water with oxygen too low to support most aquatic life.
What is the difference between eutrophication and cultural eutrophication?
Eutrophication is the natural buildup of nutrients in water over time, while cultural eutrophication is caused by human activities adding extra nutrients like fertilizers and wastewater.
How can algal blooms be harmful to humans?
Algal blooms can be harmful to humans by producing toxins that contaminate drinking water, causing illness if ingested or touched, and by creating low-oxygen “dead zones” that disrupt fisheries and food sources.
What is an algal bloom?
Rapid growth of algae in an aquatic system, often caused by nutrient pollution like fertilizer runoff
Why does losing trees increase flooding even when rainfall doesn't change?
(Simple: Why does cutting trees cause more floods?)
Answer: Trees control how water infiltrates and evaporates; without them, runoff skyrockets.
(Simple: No trees = more water stays on the surface.)
How does temperature affect the growth of different phytoplankton groups?
Simple: Which algae had the highest growth rate as temperature increased? (Study 3)
Cyanobacteria grow best in warmer water, while diatoms and dinoflagellates prefer cooler water, so rising temperatures favor cyanobacteria blooms.
Simple: Warm water helps cyanobacteria grow more, causing bigger and more frequent blooms.
How do human activities increase phosphorus in ecosystems?
Mining, fertilizers, and older phosphate detergents add extra phosphorus, which washes into soil and waterways, disrupting ecosystems.
How have humans changed the nitrogen cycle over the past 50 years?
Human activities—fertilizer production, planting N-fixing crops, and burning fossil fuels—have nearly doubled the amount of usable nitrogen in ecosystems, disrupting the natural balance between fixation and denitrification.
Why did Study 1 find a 19% nitrogen increase even without more fertilizer use?
(Simple: How does nitrogen rise without adding more fertilizer?)
Answer: Intense rainfall moves more nitrogen off the land.
(Simple: Bigger storms wash out more nitrogen.)
Why does building pavement directly increase nutrient pollution?
(Simple: Why does pavement cause more runoff and pollution?)
Answer: Because water can’t soak in, so nutrients rush into rivers.
(Simple: Pavement forces dirty water into streams.)
What is a social cost of algal blooms?
Public health risks
Water safety threats
Reduction in recreation usage
What is an economic cost of algal blooms?
High costs for water treatment
Loss of revenue in tourism & recreation
Loss of revenue in fisheries and land
Why does faster nutrient cycling increase rainfall?
(Simple: How does nutrient cycling cause more rain?)
Answer: More plant growth → more transpiration → more humidity → more rain.
(Simple: More plants = more water vapor = more rain.)
Why is nutrient pollution now a “moving target”?
(Simple: Why is controlling pollution getting harder? Think about how climate change increases precipitation....which leads to.....)
Answer: Climate change keeps increasing runoff through stronger storms.
(Simple: Storms get stronger, so runoff keeps rising.)
Why do many mitigation strategies in Study 3 lose effectiveness as climate change accelerates?
Answer: Because they rely on older climate patterns—stable temperatures, predictable mixing—that no longer exist
(Simple: Methods were designed for a different climate.)
Why does the sequence of floods followed by droughts create severe bloom conditions according to Study 2?
Floods wash nutrients into lakes and rivers, then droughts make the water warm and stagnant. This creates ideal conditions for cyanobacteria to grow—a “perfect storm” for harmful blooms. Simple: Floods bring nutrients and droughts trap them, letting algae thrive.
Why will future algal blooms be larger, longer-lasting, and more toxic according to all three studies?
(Simple: Why are blooms getting way worse over time?)
Answer: Future algal blooms will be bigger, longer, and more toxic because climate change and human activity (warmer water, extreme storms and droughts, increased nutrient runoff, and water stratification) create conditions that favor cyanobacteria growth.
Simple version: All changing conditions are helping algae thrive.
Why does Study 3 say long-term control requires multiple strategies, not one?
(Simple: Why won’t one method ever be enough?)
Answer: Blooms are driven by nutrients, heat, mixing, salinity, and water flow — no single tool addresses all of them.
(Simple: Too many causes for one solution.)
Why will phosphorus limits that worked in the 1990s no longer be safe by 2050?
Answer: By 2050, phosphorus limits from the 1990s won’t be safe because warmer, more stratified lakes respond strongly to even small nutrient additions.
Simple version: Lakes today are more sensitive, so old phosphorus rules aren’t enough.
Why do the studies indicate that algal blooms signal a breakdown of the whole ecosystem?
Answer: Blooms occur when climate extremes, excess nutrients, and water chemistry all become unbalanced.
Simple version: Everything in the system is going wrong at once.