Environment Canada has sent notice to hundreds of employees that they will be affected by a wave of job cuts that will take place over the next 90 days.

Gary Corbett, the president of the Professional Institute of the Public Service of Canada, says his union received notice about the pending cuts on Monday.

"These type of announcements cause a lot of havoc in the department and people are certainly wondering what is going to happen now," Corbett told CTVNews.ca in a telephone interview on Thursday.

Corbett said a total of 776 Environment Canada employees have since received notices that they will be affected by the job cuts, though not all of them will ultimately end up leaving the department.

Some employees will be moved into new positions within the department, while others will be offered new jobs in other parts of the public service.

"The department has quite clearly said that they expect 300 (employees) to be surplused," said Corbett.

But Bill Pynn, the national president of the Union of Environment Workers, said Environment Canada is using retirement attrition assumptions that may not prove true, which could leave the department unable to hold onto to its workers.

"I don't believe that Environment Canada has the capability to offer, to a large degree, high numbers of job offers within the department," Pynn told CTVNews.ca by telephone on Thursday afternoon.

"If I thought that they were able to do that, I would think they would have done this prior to announcing the degree of cuts that they announced yesterday."

And even if the department can provide other opportunities, Corbett said it is not a simple process to uproot scientists and other professionals from Environment Canada into other jobs.

Dozens of physical scientists and engineers within the department have received notices, as have a smaller number of chemists and meteorologists.

The Environment Canada website says the department has more than 7,000 employees, which implies that about 1 in 10 workers will be affected by the pending job cuts.

The pending cuts have also raised concerns that Environment Canada will be hard-pressed to deliver the services it is required to provide with diminished staff capacity.

Opposition critics say the cuts show the environment is not a priority for the Conservative government.

"These massive cuts are deeply alarming and will result in reduced ability to evaluate scientific issues, such as air quality, climate change, and water quality, and could potentially lead to less-informed decision-making," Liberal Environment critic Kirsty Duncan said in a statement released Thursday.

"Liberals believe that Canada needs more scientists within Environment Canada not fewer -- but clearly the Conservatives disagree."

In a statement released Wednesday night, Green Leader Elizabeth May said: "At the very least, the Harper government owes the public clear explanations of how the core activity of Environment Canada will not be harmed by these layoffs. What is the timeline and what areas of the department will be affected? How will we ensure that critical roles are not left vacant?"

"There are too many questions and no good answers regarding this slashing of a critical government department."

In a statement from Environment Canada to CTVNews.ca, the department said the environment "remains a priority" for the government, "even in times of fiscal restraint."

It noted that the last federal budget committed investments towards cleaning up the Great Lakes, mitigating the effects of climate change, protecting the health of Canadians from contaminated sites, and improving meteorological services.