Chesapeake Bay: US Coast Guard

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.

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

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

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?

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

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

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

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

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

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