Who looks sad, dejected, and worried? What does Salerio say about Antonio's sadness?

In the opening scene of the play, Antonio tells Salerio that he is very depressed, worried, and tired. Salerio comments that Antonio is feeling upset because his merchant ships are out on the treacherous sea where he risks losing much of his wealth. However, Salerio doesn't blame Antonio for feeling depressed and dejected because he understands that if his precious ship Andrew were in similar danger, he would be reminded of his potential loss everywhere he went. Salerio mentions that he couldn't imagine the stress that Antonio is under and is sure that Antonio is lamenting about his merchant ships. Despite Salerio's sensible assumption as to why Antonio is depressed, Antonio reassures Salerio that he is not worried about his merchandise because his investments are not all on one ship.