Intercontinental movement of exotic fungi on decorative wood used in aquatic and terrestrial aquariums

The intercontinental movement of fungi or fungus-like organisms brings nonnative species into areas where they may become invasive pathogens of trees and other plants. In the past century, many examples such as Dutch elm disease, sudden oak death, laurel wilt, and others have resulted in large economic losses and ecological disasters. Although various safeguards to prevent the transport of potential pathogens have been in effect, new avenues of introduction have occurred causing new disease outbreaks. This study examined fungi in wood shipped from Asia that is used for decorative purposes in aquatic and terrestrial aquariums. From 44 imported wood samples, 202 cultures representing 123 different fungal taxa were obtained and identified using molecular methods. These included 31 species not previously reported in the United States, 21 potential plant pathogens, 37 species of wood decay fungi and 24 taxa with a 97% sequence match or less to known isolates suggesting these are unknown species. The results demonstrate that wood used for decorative purposes in aquariums harbor large numbers of diverse fungi that remain viable during shipping and storage. These fungi are currently being imported into areas where they are not native, and they may pose serious biosecurity threats to the United States and other countries around the world.