1. Chesapeake Bay: US Coast Guard

2. The Chesapeake Bay Watershed
Chesapeake Bay Watershed: US Department of Agriculture
Begin with a map of the Bay and close up images of the rivers from six states and the District of Columbia that feed into the Bay. Note that there are two maps of the same area on the slide. The map on the left shows the geographic area, but the map on the right shows the waterways involved in the watershed. Ask students to share what they remember from the watershed and estuary lessons at the beginning of the unit and ask them to use the map in their discussion.

3. Largest estuary in the United States
Share that the Bay is the largest estuary in the United States. Guide students in making connections to their previous estuary lessons.
Bay Map: NASA
Largest estuary in the United States

4. No other American estuary has a higher yield
Fishing Industry of:
No other American estuary has a higher yield
Blue Crab
Oysters
Striped Bass
Clams
Share that no other American estuary has a higher yield of fish and seafood (including blue crab, oysters, clams, and striped bass).
Blue Crab: The Children's Museum of Indianapolis
Oyster: David Monniaux
Striped Bass: Mike Smedley
Clam: Aung/Wikipedia

5. The Bay is not healthy…
Direct students to notice the bright green areas in this small area of The Bay. Those are areas where algae is growing quickly (algal blooms). Ask students what they think cause algal blooms?

6. Nutrient Pollution Causes Algal Blooms and Fish Kills
This is a close up of an algal bloom. Students will note the dead fish and this can lead to a discussion about the consequences of algal blooms. But where does nutrient pollution come from? Remind students of their work during the watershed modeling lesson when they “polluted” the watershed with food coloring in order to model runoff. Ask students to share connections between that lesson and what is happening in The Bay. What kinds of sources for water pollution might be affecting
Algal Blooms: Jennifer L. Graham/US Geological Survey
Nutrient Pollution Causes Algal Blooms and Fish Kills

7. What causes the excess nutrients?
Rivers and tributaries are bringing the nutrients to the Chesapeake Bay:
Sewage
Farming
Factory farms discharge 650 million lbs of chicken manure each year
Confirm the sources of the runoff for The Bay with students. Factories and farms exist all along the tributaries that lead into The Bay. This carries extra nutrients into the water, leading to algal blooms.
Hog Farm Waste: USDA
Chickens: SRAP
Pigs: Farm Sanctuary

8. Nutrients, Algae and Fish Kills
Dead zones appear in the bay where nothing can live
Low dissolved oxygen in the water kills fish and other organisms
Microbes use the oxygen in the water
Detritus is decomposed by microbes, microbe populations boom.
Algae die and become detritus (decaying matter)
Adding nutrients causes algal blooms
In normal ecosystem low nutrient levels keep algae in check
Walk through the process by which algal blooms cause dead zones by reading through the graphic. Tell students that algae exists normally in the water, but that increased nutrients causes the algae to reproduce rapidly, resulting in an “algal bloom.” Normally, we might think of the term “nutrients” as being a good thing. But in this case it might have positive effects on one organism (the floating algae) but negative effects on other organisms in the ecosystem.
When the algae die it becomes detritus (decaying matter) that is decomposed by microorganisms. The microorganisms (microbes) use oxygen from the water. This causes the dissolved oxygen levels to be low, which means that fish and other organisms can’t survive. This causes a dead zone, or an area where nothing can survive.
Dead Fish: US Geological Survey
Fish kill caused by nutrient build-up, Nanticoke River, Chesapeake Bay, 1992

9. How have humans activities impacted the Chesapeake Bay ecosystem?
Longshoreman Atlantic City: Isabella & Carroll Walker Collection/The Norfolk Public Library

10. To Investigate this question you will:
Analyze historic and modern day food webs
Chart trends in harvesting and ocean health using real data on the Chesapeake Bay
Draw conclusions from your analyses to determine how humans have impacted the Bay
Explore the biodiversity loss of the Bay and connect it to local ecosystems

11. Image Credits
Chesapeake Bay: US Coast Guard
Chesapeake Bay Watershed: US Department of Agriculture
Chesapeake Bay Map: NASA
Blue Crab: The Children's Museum of Indianapolis Oyster: David Monniaux Striped Bass: Mike Smedley Clam: Aung/Wikipedia
Map: NASA
Algal Blooms: Jennifer L. Graham/US Geological Survey
Dead Fish: US Geological Survey
Hog Farm Waste: USDA Chickens: SRAP Pigs: Farm Sanctuary
Longshoreman Atlantic City: Isabella & Carroll Walker Collection/The Norfolk Public Library