In my tooling around the Internet for Marmorkrebs related research, I found this risk assessment for Marmorkrebs as a potential non-indigenous crayfish in Ireland. It seems to be an extremely thorough document.
Marmorkrebs are not the only crayfish assessed, either. Noble crayfish (Astacus astacus), Turkish crayfish (A. leptodactylus), spiny-cheek crayfish (Orconectes limosus), signal crayfish (Pacifastacus leniusculus), and the champion non-indigenous crayfish, the Louisiana red swamp crayfish (Procambarus clarkii) all get similarly extensive review.
Non-native Species Risk Assessment for Ireland