In contrast to many other marine regions, chemical interactions between organisms in Arctic waters are little understood. This project investigates natural products and chemical interactions in the sponge genus Haliclona in temperate and polar waters. Several new secondary metabolites isolated from Haliclona show feeding deterrence and activity against bacteria and fungi, but the compound composition varies with habitat and year. That raises the question whether sponges of the genus Haliclona as a model are able to adapt to changing environmental factors such as water temperature and colonization by bacteria by varying their secondary metabolite composition.