With increasing popularity of using ontologies, many industrial and clinical applications have employed ontologies as their conceptual backbone. Ontologies try to capture knowledge from a domain of interest and when the knowledge changes, the definitions will be altered. We study change management in the FungalWeb Ontology, which is the result of integrating numerous biological databases and web accessible textual resources. The fungal taxonomy is currently unstable and evolves over time. This evolution can be seen in both nomenclature and the taxonomic structure. In an experiment we have focused on changes in medical species of fungus which can potentially alter the related disease name and description in an integrated clinical system. In order to address certain aspects of representation of changes in an ontology driven clinical application we propose a methodology based on category theory as a mathematical notation, which is independent of a specific choice of ontology language and ...