Question

An ecosystem is a community of living organisms and the nonliving components of the environment. Energy flows in an ecosystem in one direction through food chains, and a food web is made up of all the food chains within a community of organisms. Biodiversity refers to the variation in species found within an ecosystem, and it is measured in two ways: (1) species richness, which is the total number of different species in an ecosystem; and (2) relative abundance, which is a measure of how common each species is within the ecosystem. Biodiversity and complex feedings relationships within an ecosystem help maintain sustainability.

Consider the aquatic Michigan food web. Notice the non-native predator, the sea lamprey, at the top left corner. Explain how the presence of the sea lamprey will impact this food web.
Responses
A Eventually, there will be a total collapse the food web due to the presence of the sea lamprey.Eventually, there will be a total collapse the food web due to the presence of the sea lamprey.
B The consumers with the purple and blue bands will become extinct. The producers and herbivores will dominate the ecosystem.The consumers with the purple and blue bands will become extinct. The producers and herbivores will dominate the ecosystem.
C The third level consumers will eventually be wiped out and there will be a huge rise in the producers and first level consumers.The third level consumers will eventually be wiped out and there will be a huge rise in the producers and first level consumers.
D Some of the third level consumer populations may decline, but because of the complexity of the food web, it will sustain itself over time.

Answer 1

D

Explanation: As a new top predator, the sea lamprey can reduce populations of some higher-level consumers, but a complex food web has multiple pathways and species redundancies that often allow the system to persist (though altered). Answers A–C are too extreme or categorical — total collapse or wholesale extinction/wiping out is unlikely immediately because of the network of interactions and buffering provided by biodiversity, even though significant declines and ecosystem changes can occur.