In carefully analysing the use of the phrase harmful algal bloom in specialized discourse (i.e. marine biology) from the point of view of frames and semantic roles, this paper introduces a model of specialized concept representation based on conceptual frames and blends. The analysis shows that frame-blending, although not previously studied in specialized language, has great potential to represent the dynamic processes that take place in specialized fields of knowledge. It is argued that conceptual blending is a valuable complement to frames, particularly when it comes to describing and explaining existing scientific knowledge.