Final answer:
The presence of nutrients is an important factor in determining the distribution and abundance of organisms in aquatic ecosystems.
Step-by-step explanation:
The factor that influences where an organism lives in an aquatic ecosystem is the presence of nutrients. Nutrients such as nitrogen and phosphorus are essential for the growth and survival of organisms in aquatic environments. They serve as building blocks for proteins and nucleic acids and are necessary for basic metabolic processes.
For example, in a freshwater ecosystem, the availability of nutrients like phosphorus can determine the growth of algae. Algae are the primary producers in freshwater ecosystems and serve as food for other organisms. If there is an abundance of phosphorus, algae blooms can occur, which can lead to changes in water quality and the balance of the ecosystem.
In summary, the presence of nutrients is an important factor in determining the distribution and abundance of organisms in aquatic ecosystems.