Question

use the information to answer the question. elizabeth is using a computer simulation. she can increase or decrease populations to learn how changing conditions affect the stability of the ecosystem. river food web which change will allow elizabeth to best test how competition between wading birds and large fish affect the stability of a river ecosystem? a making fishing seasons longer b more ducks migrating to the river c pollution decreasing the population of bivalves d introducing an invasive aquatic plant to the river

Explanation:

Step1: Analyze the food - web

The wading birds and large fish are part of the river food - web. We need to find a change that affects their competition.

Step2: Evaluate option A

Making fishing seasons longer directly affects large fish populations but has little to do with the competition between wading birds and large fish.

Step3: Evaluate option B

Removing ducks, which are also part of the food - web, can change the food availability for wading birds and large fish. Since ducks and wading birds may compete for some food sources (like small fish), and large fish may also be affected by changes in the food - web due to duck removal, this can test the competition between wading birds and large fish.

Step4: Evaluate option C

Pollution decreasing the population of bivalves mainly affects the part of the food - web related to bivalves and their predators, not directly the competition between wading birds and large fish.

Step5: Evaluate option D

Introducing an invasive aquatic plant mainly affects the plant - based part of the food - web and may have indirect long - term effects, but not as directly as option B on the competition between wading birds and large fish.

Answer:

B. removing ducks, migrating to the river