This is a very interesting topic.
There are loads of ways in which a team can start to disintegrate. Arguments, insults, unhelpful behaviour, back seat driving, second guessing every decision.
Even if it's just one person out of a crew of 4 the negative effect that it has on the cohesion and morale of the entire group can be catastrophic.
I tend to try and inject humour into the situation, getting people laughing at something else can be a good way of alleviating the tension in those sorts of situations. Having a clumsy crew member who is prone to p**t falls is great for that (kinda like Randall in black sails).
If it is going to far and descending into an argument, it's probably too late for humour. That's when I tend to be a bit firmer, and insist that both sides get over it and we move forwards. The exact words I use are normally "Look, it's over now, let's just move past this"
In the worst cases I'll tell the crew that if they don't put their handbags away I'm leaving, but to be honest if it's gotten that bad there's probably no saving that particular crew.
At all times I try to make sure that I am respectful to my crew members, I don't bark orders and I don't criticise performance. It's much easier to get people to follow you if they feel supported and respected, even if you as captain aren't overawed with their playing. Compliment them on whatever it is that they are doing well (there must be something, even if it's just being the drunkest sailor) and offer advice as to what you might do differently, never demand, never criticise, it's important that your crew feels valued and able to trust one another.
If you are in a leadership position, your main goal should always be that the people on your ship enjoy themselves. The only reason to put on the grown up voice and be a bit more authoritarian is if a crew member's language, attitude or behaviour is causing conflict or disunity within the crew.
A good way of handling the back seat driving/second guessing is to let that person be in charge for a bit or give them some other critical role to perform, if they're busy doing something else then they won't have time to be criticising everything.