1. CER practice tool
Notebook pages 57-58

2. Scientific question – top page 57
How have human activities impacted the Chesapeake Bay ecosystem?
Claim: Humans have negatively impacted the Chesapeake Bay ecosystem.
A) Is in every ecosystem

3. Background knowledge
The bay changed significantly when humans came in the 1750’s. Many organisms became rare.

4. Initial Thoughts
Humans pollute the Bay.

5. Evidence
Claim
Science Concepts
Alligators and manatees went extinct.
When humans began large-scale fishing, the ecosystem’s food web was dramatically changed.
Food web diagrams
In 1700, floating algae to sea floor algae ratio was 1.0 (balanced). In 1981, the ratio was 8:1 – 8 times the amount of floating algae.
Nutrient levels have increased dramatically in the Bay in the last 300 years.
Data table/graph
Between 1883 – 1891, over 1,700,000 metric tons of oysters were removed from the Bay. In 1957, floating algae was 6 times higher than seafloor algae.
As the oyster population decreased, the floating algae population increased.
Data tables
1750’s settlers began farming, raising cattle, and building homes – oysters were not hunted until late 1800’s(early 1800’s floating algae population increases)
Humans began impacting the Bay even before oyster harvesting became popular.
Data tables and background information

6. Top box page 58
Claim: Humans have negatively impacted the Chesapeake Bay ecosystem.

7. Does your claim agree with your initial thinking? Why or why not?
Look at what you wrote on your initial thoughts? Did you think humans would impact the Bay this much?

8. Scientific Reasoning
The evidence that led to my claim is extinction of manatees and alligators, increase in the floating algae population, evidence that as the oyster population decreased the floating algae population increased, and that when humans came in the 1750’s they effected the Bay.
The concepts that relate to the evidence and support my claim are use of data tables, graphs, food web diagrams, and analysis questions.
These concepts support my claim because they show a direct correlation between the loss of oysters and the increase of floating algae – human impact.

9. Scientific Explanation
My evidence is the following: (copy your four pieces of evidence)
Evidence 1
Evidence 2
Evidence 3
Evidence 4

10. Evidence: one piece from each section
Food webs: before and after comparisons (think worksheets 1 and 2)
Oyster and algae data (pages 51-56)
Dead zone lesson (pages 27-29)
Worksheet 4 page 56
Scientific Question: How have human activities impacted the Chesapeake Bay ecosystem?

11. Graded on…
Claim
Evidence
Science Concepts
Scientific reasoning

12. How to cite evidence
When humans began large-scale fishing in the Bay, the ecosystem’s food web was dramatically changed.
Evidence: Evidence from food webs.

13. Nutrient levels have increased dramatically in the Bay in the last 300 years.
Evidence: The ratio of floating algae to sea floor algae has increased over the last 300 years.

14. As the oyster population decreased, the floating algae population increased.
Evidence: Evidence from graph

15. Humans began impacting the Bay even before oyster harvesting became popular.
Evidence: The floating algae levels were increasing in the 1700’s before the oysters were even harvested. This was the time period when farming was being established in the area and nutrients were being added to the Bay.