In environmental databases there is a plethora of data, described in different terminologies, stored in different data structures and referring to distinct time periods and locations. Thus it is difficult for non-experts to find the data they are looking for. Adding an ontology-layer, which provides semantic enhancement, provides the underlying data structure for an open and intuitive search interface for non-experts. In this paper, we present the design of a bilingual eco-ontology using fuzzy mappings and loosely bridged ontologies which introduce a semantic layer in an existing environmental database storing data in German and French.