Stingrays: Cloutier sends message to players (VIDEO)
The trio of forward changes – first revealed on sporthull.co.uk yesterday – comes on the back of just two wins in the last 11 games.
The run has left Stingrays second-bottom of the Elite League and already out of this season's Challenge Cup.
Stingrays are currently leaking nearly four goals a game, while scoring only two per match.
James Sanford has already arrived to bolster the defence, while the signing of fellow Canadian Silverthorn should improve the team's points scoring rate.
Cloutier said: "Jason has a lot of skill and will bring speed up front. He will also put the puck in the net.
"I am really excited to have Jason in our line-up.
I will be counting on him. He has a great offensive threat, he is a good all-round player.
"Hopefully the other guys will get the message we are serious about making changes. If we have to make them we will do."
Canadian Reynolds was Stingrays' second-top points scorer last season, deprived of top spot only by a four-week absence due to a broken finger.
However, he has struggled this season, with just five points in 11 games.
Long-serving Koulikov has managed just three.
With forward Lee Mitchell nearing full fitness after a knee injury, Cloutier decided to wield the axe on two, rather than just one player.
"Mitch will probably be ready next week, and I had a look at our Brits and made a decision.
"It just didn't work out between me and Slava," said Cloutier.
"Matt is a very good player and a great person, but I just think he was struggling."
Silverthorn, 30, was expected to fly into Britain today and should make his debut in Coventry tomorrow.
Stingrays' fans will get the first glimpse of their new man on Sunday against Belfast at Hull Arena.
Cloutier denied any further signings are in the pipeline, but admitted he is anxious to get a settled squad before Christmas.
Hull Stingrays' Sylvain Cloutier
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