Algae & Brine Shrimp Population Dynamics

by Colby S. (7th Grade)

Q1: Based on the experimental results, what factors placed limits on the algae populations? What is your evidence?

• Answer: Algae population growth was limited primarily by nutrient availability and grazing pressure from brine shrimp.
• Evidence: In the experimental trials, the algae population did not grow infinitely; instead, it leveled off and stabilized. When brine shrimp were introduced, the algae population was kept in check because the shrimp actively consumed the algae as a primary food source.

Q2: Based on the experimental results, what factors placed limits on the brine shrimp populations? What is your evidence?

• Answer: Water temperature was the primary factor limiting the brine shrimp population, while light levels had no significant impact.
• Evidence: The data showed near-zero hatch rates and minimal population growth in cold water conditions. Warmer temperatures resulted in a substantial increase in active brine shrimp. Variations in light levels produced no noticeable change in population size, proving temperature to be the key abiotic driver.

Q3: What additional abiotic and biotic factors might limit population size in the real Mono Lake ecosystem?

• Answer:
  • Abiotic Factors (Non-Living):
    • Climate change of the temperature
    • High evaporation or stream diversion increases salt concentrations, which can disrupt brine shrimp hatching and algae growth.
    • Mono Lake’s highly alkaline, basic water limits which organism species can survive in the ecosystem.
    • Dissolved nitrogen and phosphorus levels in the lake restrict overall primary production (algae growth).
  • Biotic Factors (Living):
    • Millions of migratory birds feed on brine shrimp, limiting their population size.
    • Brine shrimp compete directly with one another for the limited supply of algae.
    • Water diversion projects by human historically altered lake levels and food web stability.

(formatted with AI assistance)