Media Studies is an established research field. What are the experts in this field called? Media Researchers? Media Experts? ...
When this field is understood to be the only topic, calling them 'researchers' is sufficient. It is understood that they research 'media studies' because that is what the topic is about.
When the topic is broader, or they have not been introduced, you might call them
media studies researchers, and then continue with 'researchers' for the remainder, or until another field is mentioned.
I cannot speak for the definitely correct usage past this, but I believe 'media researchers' would be acceptable. However, I would avoid this and stick to referring to these people by name, by their actual job, or as above.