Answer:
The eutrophication of oceans.
Step-by-step explanation:
This is the result of an increase in phosphates and nitrogen dissolved in water, at the end when it reaches the oceans, they are going to deposit in the bottom of the ocean and they are going to promote the production of algae.
With an increase of the population of algae, the sunlight will not reach the bottom, will consume the oxygen of the oceans, leaving a reduction in fish and other living things population.