Question

the manager of a trout hatchery notes that a nearby lake has overabundant growth of algae and other water plants. she says that this growth could eventually cause the fish in the lake to die. which of the following statements explains why the fish would most likely die? a. as the algae and plants die, oxygen needed by the fish is used up by decomposers. b. the overabundant plant growth leaves little room for fish to survive. c. as plants die, they rot and release a poison that is toxic to fish. d. the algae collect on the gills of the fish, making it difficult for the fish to breathe.

Explanation:

To determine why fish would die due to overabundant algae and water plants:

• Option A: When algae/plants die, decomposers (like bacteria) break them down. This decomposition process uses oxygen from the water. Fish need dissolved oxygen to breathe, so if decomposers use up the oxygen, fish can suffocate. This is a valid ecological process (eutrophication - related oxygen depletion).
• Option B: Fish live in the water column, and plant growth (mostly in the water or at the bottom) doesn't significantly limit physical space for fish to swim/survive in a lake context. So this is incorrect.
• Option C: Decomposing plants don't typically release a "poison" toxic to fish. The main issue with plant decay in this context is oxygen depletion, not toxin release. So this is incorrect.
• Option D: Algae are microscopic or small, and they don't "collect on the gills" of fish to block breathing. Fish gills are adapted to filter water for oxygen, and algae in the water don't physically clog gills in this way. So this is incorrect.

Answer:

A. As the algae and plants die, oxygen needed by the fish is used up by decomposers.