The diagram shows a simplified marine food web.
An infectious disease caused a rapid decline in the population of seals in this ecosystem. Consequently, researchers observed a significant decrease in the population of zooplankton.
What is a possible reason for the decrease in the zooplankton population?
The small fish and squid switched to consuming phytoplankton as their primary energy source.
There was increased predation on zooplankton by small fish and squid due to a release from seal predation.
The competition between small fish and squid for zooplankton decreased.
The abundance of phytoplankton decreased, which directly reduced the birth rate of seals.