Trade Union leaders are worried that a merger would have serious consequences for NZME and Fairfax NZ staff.
Hundreds of New Zealand journalists face an uncertain future if the planned merger gets the green light.
Media companies Fairfax and APN have told the New Zealand Stock exchange they are in talks about merging their New Zealand businesses by the end of 2016.
NZME - the New Zealand arm of APN - owns several North Island daily papers and radio stations, while Fairfax's media portfolio includes newspapers, magazines, such as Cuisine, TV Guide and NZ House & Garden, and the country's most-visited news website Stuff.co.nz.
E Tu union has been handling media job losses for years, with the most recent occurring last Friday, and media organiser Paul Tolich said he feared things would get worse.
"I think it will lead to a decline in the available jobs for journalists. They have already cut the numbers of subeditors to a very small number, and you can see that they are now going to cut reporters and front line journalists."
If completed, the combined company would own a host of New Zealand's newspapers, including The New Zealand Herald, The Press the Sunday Star-Times and the Dominion Post, as well as the radio networks ZM, NewstalkZB, Radio Sport and Hauraki.
The two businesses have a combined workforce of more than 3000 people and former NZ Herald editor Tim Murphy estimated a merger could cost up to 750 jobs.
Mr Tolich said the proposed merger would also lead to less variety in news gathering and could jeopardise democracy.
"The traditional role of the media was to uncover the stories about the powerful and about major institutions which were abusing their power.
"It used to be called the fourth estate and that was one of the pillars, along with the courts and parliament that was the balance in society to keep it free and democratic."
Mr Murphy said the merger would inevitably mean there would be fewer journalists, but future job cuts by the individual companies were always going to happen.
He said the merger could see a paywall erected on a combined news website or membership schemes introduced for digital news, as the worry about what their competitor was doing would evaporate.
He said the merger may mean things may move faster.
"Both groups have been cutting their journalistic staff because of the perils of the print industry and that's been going on for years and has been accelerating. And it would have had to keep happening again and again, because nobody is able to get the golden egg of how to make money from digital."
On past guesstimates, the 3000 combined staff of Fairfax NZ and NZME could not be halved by merger - probably need upwards of 2250— Tim Murphy (@tmurphyNZ) May 10, 2016
But the merged company would still face stiff digital competition from the likes of Facebook, Google, Snapchat and other social media companies, he said.
Read the announcement here (pdf download)
Media commentator Gavin Ellis - another former NZ Herald editor - said the only way forward for the newspaper business was consolidation, which might keep the business running in the long term.
But in the short term it would mean job cuts as the organisation's newsrooms, advertising, and back office were merged into one national company.
Dr Ellis could not see any reason why the Commerce Commission would not approve the merger.
He said they would look at the entire advertising market, where there was plenty of competition.
'There will be double-ups all over the country'
One senior Fairfax reporter said staff were worried about cuts this morning.
"We know literally nothing about how it is going to work. There will be double ups all over the country if we merge. We cut staff last year and now there will be more.
"We are going to have months worrying about who gets what jobs."
Another reporter said: "We are not going to have as many reporters or managers. We won't need as many people online or for the print sites. People are worried."
A third Fairfax journalist said the reality would be further job losses.
"They are not going to need two of everything - two political editors, two sports editors, two editors-in-chief."
The person said it was inevitable that good staff would look to leave as the deal, if it went ahead, wouldn't be sealed until the end of the year.
Another Auckland staff member told RNZ News everyone was a little rattled.
"The next six months, you've just got to dig it in, who knows what will happen really."
She said staff were not told if their jobs would be affected because the merger was still being negotiated.
"They said when more information is available they'll let us know."
How it could affect readers
Labour's consumer affairs spokesperson said a merger between Fairfax and APN would be terrible for democracy in New Zealand, and for news consumers.
David Shearer said a merger would have huge implications.
"It basically means we will have one newspaper nationwide, rather than two, so you eliminate the competition. I think that is terrible, it gives people less ability to hear different voices in the media."
Merja Myllylahti, an expert in media ownership at AUT, told RNZ the merger was potentially a seismic shift in media in New Zealand, and would affect readers as well as journalists.
She said regional news could suffer.
"I'm afraid that if they don't have all the resources to provide local news, all we'll have is clickbait, and more and more of that would be a worry."
She said some kind of paywall was likely under a merged company.
"Because they have a duopoly, they haven't been able to do that, because if one was launched first, then other readers would escape to that free site. But now if they merge, I would bet they would introduce digital subscriptions."