What does it mean when their is only a few mosquitoes but lots of gnats?

I live down south in Louisiana. Since their has been an increase in water levels because of the Mississippi and water from up-north there has been a tremendous decrease in mosquitoes, but a tremendous increase in gnats. I only see a few small mosquitoes every once in a while, but I mainly see gnats which bite. Can you please tell me why this is happening? Is it because of the water or what? Can you please leave detailed info? Thanks