Investigating Hypoxia in Long Island Sound

Part 1: Engage - The Mystery of the Summer Fish Kills

Every summer in Long Island Sound, oxygen levels drop dangerously low near the bottom, causing mass die-offs of fish and other marine life. Oddly, there is no visible “poison” being added to the water.

Think & Discuss:

• What factors do you think could cause oxygen to disappear from the bottom of an ocean bay?
• How might human activities on land affect what happens underwater?
• Write down at least two “need to know” questions about this phenomenon. ___ _______

Part 2: Explore - Simulation Investigation

Open the Long Island Sound Hypoxia Simulation. This computational model simulates a vertical slice of the water column over an annual cycle.

Variables to Explore:

1. Nutrient Runoff (Nitrogen): (0-100) Represents fertilizer from lawns/agriculture and wastewater treatment plant discharge.
2. Surface Temperature: (10-30°C) Summer heating warms the surface water, reducing its density.
3. Wind Mixing (Mystery Factor “X”): (0-100) Observe how it affects the water column layers and oxygen levels.

Instructions:

1. Set Surface Temperature to 15°C, Nutrient Runoff to 20 (Low), and Wind Mixing to 100 (Stormy). Observe the stratification and chart.
2. Gradually increase Surface Temperature to 25°C. What happens to the water column?
3. Increase Nutrient Runoff to 80 (High). Wait a few simulated weeks. What happens to the algae and dissolved oxygen?
4. Record your observations in the data table below.

Note: You can also use the “Start Annual Simulation” to watch these factors change naturally over a year.

Part 3: Explain - Making Sense of the Data

Using your data from the simulation, answer the following questions:

1. Stratification: How did increasing the surface temperature affect the water column? Why does this separation (stratification) matter for the bottom layer? ___ _______
2. Algae and Nutrients: What happened to the surface algae when you increased Nutrient Runoff? ___ _______
3. The Hypoxia Connection: Look at the “Summer Calm” data row. Explain the chain of events that leads from high nutrient runoff at the surface to low dissolved O₂ (hypoxia) at the bottom. ___ _______

Part 4: Elaborate / Evaluate - Human Impact & Systems Modeling

Deliverable: Using evidence from the computational representation, write a scientific explanation describing how human activity (nutrient runoff) modifies the relationships among Earth systems (the biosphere/algae and the hydrosphere/ocean water) in Long Island Sound.

In your explanation, be sure to:

• Identify the relevant components of the modeled systems (inputs, outputs, boundaries).
• Illustrate the relationships between the Earth systems (e.g., how changes in one system drive changes in another).
• Describe how human activity could affect these relationships in the future. ___ _______

Teacher Notes (NGSS Alignment)

Performance Expectation: HS-ESS3-6: Use a computational representation to illustrate the relationships among Earth systems and how those relationships are being modified due to human activity.

Science and Engineering Practices (SEPs):

• Using Mathematics and Computational Thinking: Students use a computational simulation of phenomena to describe and support claims about how nutrient runoff and temperature affect marine ecosystems.

Disciplinary Core Ideas (DCIs):

• ESS3.D: Global Climate Change: Through computer simulations and other studies, important discoveries are still being made about how the ocean, the atmosphere, and the biosphere interact and are modified in response to human activities.

Crosscutting Concepts (CCCs):

• Systems and System Models: Students analyze inputs (nutrients, heat) and outputs (algae growth, dissolved oxygen levels) to describe interactions between the biosphere and hydrosphere.

Evidence Statements Addressed:

• 1.a. Representation: Students identify the relevant components of the modeled systems (algae, oxygen, temperature, nutrients, water layers) and their relationships. (Demonstrated in Part 3 and Part 4 explanations)
• 2.a. Computational modeling: Students use the computational representation to illustrate relationships among Earth systems (how nutrient input drives changes in algae, which then drives changes in dissolved oxygen in the bottom layer). (Demonstrated in Part 4 deliverable)
• 3.b. Analysis: Students use evidence from the computational representation to describe how human activity (nutrient runoff from agriculture and wastewater) modifies the relationship between the biosphere and hydrosphere. (Demonstrated in Part 4 deliverable)