Final answer:
Without the initial population size of the Atlantic herring, it is impossible to state how many would remain after a 55% decrease due to a reduction in plankton. Factors such as pollution, overfishing, and climate change can impact marine ecosystems and affect population sizes of species like herring.
Step-by-step explanation:
If there were a severe reduction of plankton available to the Atlantic herring population, leading to a 55% decrease in the herring, to determine how many mature Atlantic herring would be supported by the ecosystem, we would need to know the initial population size of the herring. Without this information, it is not possible to provide a specific number. Typically, ecologists would use survey data or estimates of the current population to calculate what a 55% decrease would represent in absolute numbers.
Such a decrease in herring due to a reduction in plankton availability could be linked to factors affecting the marine ecosystem, such as pollution, overfishing, or changes due to climate change. These alterations in key species like plankton can ripple through the food chain, impacting not just herring, but also other species that depend on them, including predators like seals or humans who fish for them. This interconnection highlights the importance of conservation efforts and sustainable practices in maintaining healthy marine ecosystems.