Why are there coral reefs found on the southern east coast of U.S. and not at the same latitude by west coast?

Question

Why are there coral reefs found on the southern east coast of U.S. and not at the same latitude by west coast?

Answer 1

Its because of upwelling and strong cold coastal currents that reduce water temperatures in these areas.

Answer 2

warmer currents from south on the east coast: coral needs warm water