Question

In a lake with three trophic levels (non-native fish, zooplankton, algae), an algal bloom occurs when the small population of zooplankton declines due to the predation of the invasive fish. Which of the following describes why zooplankton are the keystone species in this scenario?

Zooplankton are the smallest of all the herbivorous marine mammals in their communities.
The small population of zooplankton have an unequal effect on the marine community.
Marine mammals depend upon the work of zooplankton to convert sunlight into food.
Zooplankton help other populations survive by keeping out other herbivores.

Answer 1

The small population of zooplankton have an unequal effect on the marine community.

Step-by-step explanation:

According to this question, there are three trophic levels of organism in a lake as follows: non-native fish, zooplankton, and algae. However, due to the declination in the number of zooplanktons in the lake as they were fed on by the non-native fish, the algal population increased to form a BLOOM.

This bloom of algal species can be attributed to the lack of zooplanktons, which represented the only herbivorous (plant eaters) organism in that community. Hence, their relatively small population have an unequal effect on the marine community. This means that the small population of zooplanktons caused an imbalance in the community and this is why ZOOPLANKTON is the keystone species in this scenario.