Hi,
I have been through several acquisitions on the buy side because that's the major part of my job - acquisitions. Usually a big company acquiring a small one for a technology you are pretty safe if you're a technical person, less so if you're the CFO or HR person for the small fish.
Often the acquirer will realise some small economies of scale by taking over your basic business infrastructure needs (logistics, controlling, HR etc.) but really needs the tech and commercial people to stay, because the tech is useless without the knowhow that's usually locked in their heads.
Take your raise/signing bonus and be happy; there's always a higher turnover after an acquisition and the acquirer will often want the best people to stay on and take higher positions later after they've had a chance to assess their talents and motivation. Hiring talent is expensive and a crapshoot, so if they find you're good (be proactive, help out, speak up, manage the project where appropriate etc.) you'll probably find more opportunities. In my experience though, the squeaky wheels are usually the ones you want to get rid of because they demand a lot and don't contribute in line with that. Possibly that's a biased opinion, but it's likely your acquisitions team will think similarly.
So if you want to stay, show your value then ask for your raise, and be prepared with another job when you make that request.