Solo Swan concern

1. Hi I am away from home working and opposite the hotel I am staying in is a harbour, there are three swans (two coupled and one single) who have been there all week. During a walk last night the lone swan was (as always) by itself however was now very near the shore and looking out to the vast pool of water. We heard loud noises and movement in the water, where the swan was looking out. We are unsure if the noise may have been a seal and was hunting the swan. I was unable to see the solo Swan this morning and I am concerned, would a seal attack a swan? What should I do if this is the case?

thank you