Why are nutrients from fertilizer harmful to aquatic ecosystems?

Nutrients from fertilizers are harmful to aquatic ecosystems because fertilizers are often high in nitrogen and phosphorous which cause problems in aquatic ecosystems. These chemicals lead to algal blooms which causes algae to die faster and decompose thus reducing the oxygen content of the water and also hurting other organisms within the aquatic ecosystem as a result.

The answer to that would be prussia which would later be germany

Accumulating more land so that your country can continue expanding without running into problems such as overpopulation