At right conditions and taking EVERYTHING in consideration, everything could have grown back in less then 3500 years.
Simply untrue. While coral growth rates are indeed slightly variable, there's no conceivable situation that would cause them to grow at rates thousands of times what they normally do. And
certainly the conditions post-flood would not be condusive to that growth rate, or in fact, any growth rate whatsoever.
1st off, it is NOT a fictional Story,
No, it is a fictional story. It's untrue. It didn't happen. It's a myth.
We know this because it's contradicted by all avaliable evidence.
It is NOT an macro-evolutionary change
To go from fresh-water adaptation to salt-water adaptation? That's definately macro-evolutionary, if such a classification can even be said to exist. That's not a small change. That's a major change to the organism's organs, circulatory systems, and cellular chemistry.
Your also assuming that the dirt was not laid down till the very last second of the story.
It all has to be in the water at one time, T. Where else is it coming from? This is simply a spurious objection that betrays how little thought you've actually put into your flood model.
We know that all the dirt was in the water at once, according to your model, because
all fossils are the result of the flood. If all the fossils are settling out of the water at once, we know the dirt they're in must be, too.
Animals have been adapting to the slow increase in salinity over the last 4400 years.
Fresh water to 3.6% salt isn't a "slow change in salinity." That's a catastrophic change in salinity that would mean the extinction of almost every fish species, as well as the majority of marine invertabrates, like coral.
4400 years isn't enough time to expect that rapid a macroevolutionary change to occur.