http://en.wikipedia.org/wiki/Algal_bloom
It's bad.
What are you noting? The redtides? Typically redtides are only dangerous if you happen to swim in the ocean, eat tons of shellfish, or aren't adapted to it. I would understand if the ecosystem weren't adapted to it but we aren't having a redtide. As I understand it everything that's blooming is cyanobacteria. I think we should try our damndest to drop it's population (for now), check how the wildlife is doing under the blooms, make a decision after that. It may not affect the fish at all, none of them need light, it definately shouldn't starve them if it is anything like what they would normally eat (which it should be if they are a product of evolution), and as long as they are all mad up of the same type of protein there will just be a huge swarm of herbivores, then predators, and it will go all the way around until it levels out (again, only if there is something to eat the algae, I would be astounded if there wasn't).
Well... Shit, i thought the english entry has the same text as the german...
However, algal blooms are very dangerous to every ecosystem that needs light and oxygen!
Because the rapid "blooming" of the algae the nutrients and the oxygen is extracted from the water.
That kills all other wildlife. (mainly because the other fishes don't eat the algae on this planet.)
Then the algae dies too and because of the lack of aerobic decomposer, anaerobic decomposer kicks in.
These produces deadly toxins.
That kills pretty much all, expect the algae and some really hardy fishes.