It really depends. It you are indirect, your chances of a layoff increase, but if you are extremely low paid, you won't be the first on their radar. There are people who make 6 figures who's jobs are mainly rearranging powerpoint slides all day, and most of the time they make their underlings do it. They are the easiest to get rid of for the most bang for the buck. They will definitely be let go first.
Since you are new and low paid, the only way I see you being fired if if your department is made redundant. More than likely (if you are planning on moving on within a year), you will get to leave on your terms and not theirs.
Then again, the merger can change all of that. No matter what, be prepared...