Colors of Great Salt Lake
Phenomenon:
The color of the water at Great Salt Lake changes with the seasons. The south arm of the lake is green in early spring. The north arm of the lake is pink in late summer and fall.
Student Task:
Construct an explanation for what causes seasonal changes in water color at the Great Salt Lake.
Model
Students develop a model of the GSL food web, including the producers, consumers, and decomposers in the ecosystem.
Investigate
Students plan and carry out an investigation to determine the effect of different salt concentrations on brine shrimp growth and reproduction.
Obtain Information
Students read to obtain information about the physical properties of Great Salt Lake, including how water moves through the watershed.
Analyze Data
Students analyze and interpret data to identify patterns of seasonal changes in living and nonliving components of the ecosystem.
Explanation:
The water color at Great Salt Lake changes seasonally due to populations of microbes that thrive in high-salt conditions. Pink algae in the North Arm increase in the late summer and fall due to increased temperatures and evaporation of lake water. Green algae in the South Arm increase in springtime due to an influx of nitrogen as the mountain snow pack melts and waterways empty into the lake. The green water color changes back to blue by mid-summer due to brine shrimp that hatch and eat the algae, controlling the growth of the algae population.
NGSS Standards:
MS-LS2-1. Analyze and interpret data to provide evidence for the effects of resource availability on organisms and populations of organisms in an ecosystem.
MS-LS2-3. Develop a model to describe the cycling of matter and flow of energy among living and nonliving parts of an ecosystem.
Utah SEEd Standards:
6.4.1 Analyze data to provide evidence for the effects of resource availability on organisms and populations in an ecosystem. Ask questions to predict how changes in resource availability affect organisms in those ecosystems.
6.4.3 Develop a model to describe the cycling of matter and flow of energy among living and nonliving parts of an ecosystem.
Recommended Teaching Sequence:
Day 1:
Day 2:
Formative Assessment:
Use what students have written in their science notebooks as a formative assessment.
Do students understand...?
Lesson Contributor(s):
April Mitchell, Science Specialist, Salt Lake City School District