As they multiply die and decompose algae deplete the oceans surface layers of oxygen. often the large amounts of farm fertilizer that run from fields into the rivers cause algae populations to explode. the most likely result is that

The most likely result of such a condition would be the reduction in the number of animals, plants and fishes that could have survived in the water. The water would also become more acidic in nature and all living things will start dying. The water would also become unusable for the humans. This water will increase the pollution level in surrounding areas and deplete the quality of the soil.