Final answer:
Adding nitrogen to the cycle through fertilizer can impact an ecosystem by causing algal blooms in aquatic ecosystems and affecting the food availability for worms in garden soil.
Step-by-step explanation:
When humans add nitrogen to the cycle through fertilizer, it can impact an ecosystem in a few ways. One effect is that nitrogen can end up in aquatic ecosystems, which can lead to excessive growth of algae, also known as an algal bloom. This is because algae thrive on nitrogen and when there is an abundance of it, they can multiply rapidly, causing ecological imbalances.
Another impact is on garden plants, which can grow too much when exposed to excess nitrogen. This excessive growth can prevent worms from finding enough food. Worms play an important role in maintaining a healthy soil ecosystem by decomposing organic matter and enriching the soil with their castings. When worms are unable to find enough food due to the overgrowth of plants, it can disrupt the balance of the ecosystem.
Learn more about Impact of human-added nitrogen in ecosystems