Hughes, 24, was an Atlantic Division AHL All-Star in 2020-21 as he led the Providence Bruins in assists (16) and points (21) while skating in all 25 team games. He also skated in one NHL contest with Boston.
A sixth-round pick by the Bruins in the 2015 NHL Draft, Hughes enters his fourth pro season having played 135 career AHL contests with Providence, totaling 24 goals and 44 assists for 68 points. He made his NHL debut with Boston in 2019-20, appearing in one game.
Koppanen, 23, tallied three goals and three assists in 21 games with Providence in 2020-21.
Koppanen has played 119 contests with the P-Bruins over four pro seasons, tallying 16 goals and 12 assists for 28 points. He was a a fifth-round selection by Boston in the 2016 NHL Draft.