If White Dragon Ninja is on the field and a trap card is activated while the opponent controls a face-up Shooting Quasar Dragon, Quasar can negate that trap card with its effect, but it cannot destroy it. The card will be destroyed by game mechanics. If Shooting Quasar tries to negate the effect of an already face-up trap card, then that effect is negated but the trap card is not destroyed and it remains on the field.