What can result from an algal bloom in a river?

Algal Bloom in a river can occur due to the excessive amount of nutrients and minerals that are blown into the water body from any cause or any reason.

Explanation:

Algal Bloom can be defined as an excessive growth of micro bacterial organisms and algae into the water body due to the excessive presence of minerals and nutrients into the water body. The sunlight also plays an important role in the growth of these algae and micro bacteria organism. This algal Bloom is very harmful for the water body.

Due to this many fishes and aquatic organisms get killed. The most important reason behind this is the scarcity of Oxygen and sunlight which is being absorbed by the algae and other micro bacterial organisms.

ya the other dude is right

yes, because even though a theory has a  lot of evidence to support it, it is not always true