Yes, they lose all race-specific traits
To make them loyal, drop a lot of troops into that planet. Also station a BIG fleet around it. Eventually everything will be all right. SE handle planet mood in step-wise fashion: every turn the mood either increases or decreeses depending of all factors involved. Your urbam pacification centers will make them all happy eventually.
[ August 29, 2002, 19:13: Message edited by: oleg ]