I know the ascophyllum nodosum only because it's the most common variety at Hampton Beach in NH and Salisbury Beach in MA. It has little egg shaped pockets all along it's length, that I used to 'pop' as a kid. Maxicrop's entire business is thanks to this seaweed.
Some places pack there lobsters in it before shipping -- let's see if I can find a vendor online.
I don't believe it grows in warmer waters.