Mo'unga almost scored a spectacular try after the break which was ruled out by referee Mike Fraser and his assistants.
The Crusaders playmaker stole the ball after a high kick chase, eluded his opposite Harry Plummer and got extremely close in the left corner but the officials decided that a high-looking tackle by Melani Nanai was legal and that Mo'unga lost it rather than ground it on the line.
Crusaders Sam Whitelock believed it should have been a penalty try and was very vocal in saying so but Fraser was unmoved, saying Nanai's tackle was acceptable.
Bridge was over for a try in the first half only to see it ruled out for a knock-on by the Crusaders other wing Sevu Reece in the build-up. The Crusaders back three of David Havili, Reece and Bridge, plus their midfield of Ryan Crotty and Jack Goodhue were far superior to their opposites.
The visitors showed early wobbles at scrum time – the equivalent of a red blanket in close proximity to a bull – and it opened the door further for an already fired-up home side who now haven't lost at their fortress in 27 Super Rugby games.
With the Blues struggling to win their own ball in the first half and enjoying very little territory, and the Crusaders easily winning the kicking battle thanks to Mo'unga and fullback Havili, the game was effectively put to bed in the first half by the home side despite a relatively slim 13-3 lead at the break.
The red and blacks tackled with such passion and accuracy, the Blues, not a great slippery-ball side at the best of times this season, didn't have the subtlety and imagination to seriously stretch the defending champions, although Plummer's second penalty of the night did get them closer before Mo'unga extended the lead once again.
In the end the scrum contest descended into a messy war of attrition and did little to help the flow of the game.
Few of the Blues' attacking weapons handled the ball enough let along did anything dangerous with it. It was difficult to remember Rieko Ioane beating a defender before his late try and without him consistently in the game Leon MacDonald's team tend to lack real penetration.
Led by a fired-up Jordan Taufua, who ran hard and straight without any regard for his body, the Crusaders were determined to extend the Blues' losing streak in Christchurch – they last won in the south in 2004 – and after their excellent work in beating the Chiefs at Eden Park last weekend their playoffs hopes have taken another blow.
Crusaders 19 (Bryn Hall try; Richie Mo'unga 4 pens, con)
Blues 11 (Rieko Ioane try; Harry Plummer 2 pens)
Halftime: 13-3