The lecturer, who has worked there for more than 20 years, claims managers are not willing to recognise the major problems the university is facing.
It includes a dramatic fall in league tables and a drop in student numbers.
But one of the university's pro vice-chancellors said there was no problem with morale.
According to Ucas figures there were a record 12,475 applications made to Aberystwyth in 2011 - the year before higher tuition fees were introduced.
A drop from that high level was expected, but in contrast to other universities the fall in applications has continued year on year in Aberystwyth.
In 2014 it had reached 8,425.
The university has dropped from being in the top 50 institutions in 2011 to number 87 in the latest Complete University Guide league table.
In an interview with BBC Radio Cymru's Manylu programme, the lecturer said the location of the university was critical and, along with high fees, students were voting with their feet.
But they added: "In my opinion, the management methods that have been adopted have led to low levels of morale amongst staff which in turn have led to a considerable drop in the levels of student satisfaction - and this has had a negative effect on recruitment.
Dr Rhodri Llwyd Morgan, one of the university's pro vice-chancellors, denied there was a problem with morale and said around Â£100m is being invested in the campus to help attract students, increase levels of student satisfaction and improve the position in the rankings.
He added: "We're very confident when we look to the future. We can see that the investment is starting to pay off.
"We're investing in the student experience and we know that is the way to increase satisfaction... we're looking ahead with confidence, knowing that we have the plans in place for a successful future here."
Listen to Manylu on BBC Radio Cymru, Thursday at 12:30 GMT
Staff morale is very low at Aberystwyth University due to the way the organisation is being managed, a whistleblower has told BBC Wales.