Review of Positions (Box 1):
•Water connects us to nature and each other!
•Plants animals and people need clean water to survive.
•Human activity can negatively impact water quality
Our behavior is directly connected to water quality. As water travels across the watershed in streams and rivers to the Bay and Atlantic Ocean it picks up stuff that we put out on the landscape. (cars, factories, farms, homes and businesses) The things we eat, make, buy and use can impact water quality and the health of aquatic ecosystems.
Media slide presentation:
Water Habitats and the Interdependence of Species.
Image montage of food webs and aquatic species in their positions/ ecological niches.
Class Discussion: Our Connection to the Chesapeake Bay watershed's inhabitants:
Key takeaway: (MS-LS2-3)
There are winners and losers in the survival game. Plant and animal species must adapt to changing ecosystem conditions to obtain food, avoid predators and reproduce or die out. We need to better understand our dynamic connections to these ecosystems for our own adaptation and survival needs.
Media presentation: Dr. James Pierson’s work looks at indicator species in the copepod family (Arcartia tonsa)
Key takeaway: (MS-LS2-4)
Scientists need to understand the complexity of how species survive in a changing ecosystem to better investigate problems of balance. They need to understand the complex connections and web of lifelines to begin to understand why species populations rise or decline. It is their responsibility to prove or disprove the connections they predict between species and conditions in their habitat.
Activity: Apply what you learned!
Students are presented with a work sheet including three assessments:
1. Students work with a small group of other students to answer questions on what they learned from the lesson.
2. Students then interpret a new science diagram drawing on their previous experience of interpreting Dr. Pierson’s oxygen/ copepod diagram.
3. Students take an individual written test by themselves.
Who Eats Whom?
Activity A: Students create an interactive diagram of a Chesapeake Bay food web.
Key takeaway: (MS-LS2-1)
There is a diversity of interdependent plant and animal species that all rely on each other to transfer the sun’s energy and survival.
Changing Events and Balance
-Teachers present 1-3 event scenarios that impact balance in the food web. Students then predict which species are winners and losers in the food web. Ecosystem balance is evaluated by the group with each changing event.
Event A: Overfishing
When people take large predators (like Rockfish) out of the ecosystem, trophic cascade, a disruption in the food web can occur. Populations of species start to rise and fall upsetting the balance in ecosystem.
- Player’s position their life lines up above their heads as their populations increase or down to their knees to note decreasing numbers of their species. A wave of instability is clearly seen in this dynamic food web diagram.
Event B: Dead Zones
Water quality is often degraded when rain washes nitrogen off of farms and into the Bay.
This change in water chemistry can cause algae blooms that cut off sunlight and result in depleted oxygen levels in aquatic ecosystems. Many species die allowing other species who require less oxygen to take over.
- A large cloudy green image is projected overhead. Players representing underwater plants (SAVs) sit down due to lack of sunlight. Young fish now have fewer places to hide from predators and their populations decline. Eventually, larger fish suffer without the young feeder fish to eat.
- Students with red oxygen levels on their lanyard graphics must sit down while players with blue levels remain standing. The class then imagines what a permanently changed ecosystem might look like without those species: (e.g., a Chesapeake Bay with fewer fish and way too many jellyfish!)
Event C: Weather Event
A big hurricane causes the local sewage treatment plant to overflow into a Bay tributary.
The drought conditions before the storm left roadways and parking lots covered in oil and other toxic chemicals that now enter the Bay in concentrated amounts. Air pollution from distant cities gets transferred to the Bay’s waters as it rains. Wind and waves erode fragile wetlands now releasing nitrogen long stored in this buffer from farm runoff. The storm creates a shock effect on the ecosystem and it struggles to deal with multiple threats simultaneously.
- Players who represent species that are most impacted by the storm step forward and reveal the details of the threat to their survival (reading from their lanyard graphic) illustrating how weather can accelerate imbalance caused by human impacts.
Key takeaway: (MS-ESS3-4) (MS-LS2-3)
It really is ALL connected. This interactive food web diagram illustrates how the sun’s energy flows through the ecosystem from plants to animals to us! Changing conditions may upset balance and threaten chances for survival. We depend on the Chesapeake Bay’s unique positions and connections to survive and thrive.
Class Debrief and Final Discussion:
- Students read a recent news article on water quality and respond to a question:
Do you believe……?
Claim: “I agree that the ...…”
Evidence: “I back up this claim by citing facts from the article’s scientific research
(e.g., X, Y…)
Reasoning: “If scientific findings X and Y are true and fisheries are yielding more fish, crabs and oysters this year than their ecosystems overall health must be improving…”
Does everyone in the class agree with this claim and supporting argument?
Media presentation: Plankton video:
The Secret Life of Plankton
Chesapeake Bay Food Web: Introduction to plankton species, aquatic ecosystems and life in the water.