Question

A company is growing algae in big tanks to make fish food. However, the algae are not growing very quickly, and they suspect either phosphorus, nitrogen, or iron is limiting. What could the company do to figure out which nutrient is limiting?

a. Add phosphorus to one tank, nitrogen to another, and iron to a third, and see which treatment increases algal growth.
b. Add phosphorus, iron, and nitrogen to all tanks, and see which nutrient increases algal growth.
c. Add phosphorus to all tanks, because phosphorus is the nutrient that limits algal growth.
d. Add nitrogen to all tanks, because nitrogen is the nutrient that limits algal growth.

Answer 1

To identify which nutrient is limiting algal growth, the company should add different nutrients to separate tanks and observe which one causes the greatest increase in growth, with the expectation based on the common limiting nature of nitrogen and phosphorus in aquatic systems.

Step-by-step explanation:

To determine which nutrient is limiting the algae growth in their tanks, the company should employ a controlled experiment. The most informative approach would be option a: Add phosphorus to one tank, nitrogen to another, and iron to a third, and observe which treatment results in the most significant increase in algal growth.

This method, known as the limiting nutrient experiment, would allow the company to identify which specific nutrient is the limiting factor. As both nitrogen and phosphorus are known to be limiting nutrients in aquatic systems, causing rapid increases in algae growth when in high concentrations, enhancing each in isolation will lead to understanding their impact on the algae. Iron is also a necessary nutrient for algae, although typically less is required compared to nitrogen and phosphorus.