A bloomin' timeline for HABs ?

Besides better detection methods and increasing scientific awareness, frequencies and severity of harmful algal blooms (HABs) have increased over the years. This study emphasises the importance of establishing a historical baseline for HAB distributions in order to understand the future direction of HABs and their impact on coastal ecosystems. Using an eDNA metabarcoding approach, historical baseline data was established for HAB distributions around the Australian coast involving sediment samples dating from 1987-2014. 

Taxonomic identification revealed 14 different genera which identified as HAB-associated taxa. Changes in the diversity and distribution of HAB taxa over 30 years were revealed and the original sources of invasive species could be sourced. Here, Shaw et al. (2019) show historical samples to be a useful tool for retrospective biomapping of HAB species, providing insights into past HAB distributions and their effect on ecosystems, moreover this study emphasises how the shipping industry has contributed to the spread of invasive species over the years. 

This study relies on the persistence of eDNA, which degrades over time. Interpretations of these results should therefore be cautious, as observed changes in diversity could be due to the loss of eDNA in older samples. 

Reviewed paper: Shaw, J., Weyrich, L., Hallegraeff, G., & Cooper, A. (2019).  Retrospective eDNA assessment of harmful algae in historical ship ballast tank and marine port sediments. Molecular Ecology,  28, 2476– 2485.