Ecklonia radiata (order Laminariales) is a large brown alga that is a primary habitat former in the temperate rocky coastlines of Australia, and many regions in the southern hemisphere. Ongoing diebacks and disease in E. radiata and other seaweeds around the coast of Australia have raised concern over the long-term health of these ecosystems, and the economic and commercial endeavors which rely on them.
Disease in marine ecosystems across the globe is on the rise, and a substantial number of disease outbreaks in marine ecosystems are associated with pathogenic microbes and viruses. However, most pathogenic microbes and viruses that have been described are of medical or agricultural importance and not from the natural environment. This is due to the difficulties in characterizing novel microbes and viruses, which has required isolating and culturing the organism of interest. In contrast, Next Generation DNA Sequencing (NGS) can provide sequence data from genomes collected directly from of the environment without culturing. Metagenomic studies investigate these genetic “snapshots” of the microbial community; identifying functional genes and taxa in order to facilitate ecological comparisons and explore the role of known and novel organisms within the environment.
We investigate the role of viruses in disease of E. radiata by comparing the metagenomes of the viruses present in healthy and diseased kelp, in two locations on the Sydney coast. Many sequences of unknown origin and function were detected, and genes of similarity to viruses known to infect algae and plants have been identified. While there were few significant differences in the viral taxonomic assemblage between the metagenomes of viral particles from healthy and sick kelp, the profiles of metabolic functions encoded by the viral reads varied.