There is many papers that support this, but logic should be enough to describe the problem, denitrification uses No3 to breathe in anoxic conditions, what do you think it will happen to any heterotrophic organism that can’t breathe?What is the evidence that denitrifying bacteria die or go dormant or even influenced the growth of micro algae?
I’m not sure if “influence” would be the most appropriate word to describe it. Basically if denitrification can’t happen it will lead to a build up of Nitrogen.
For a bloom to develop it has many variables, it’s not always certain what organism will bloom. It could be that it will just allow GHA to grow faster as a example.