Using the molecular toolbox to compare harmful algal blooms in upwelling systems

Harmful algal blooms (HABs) are now generally recognized as occurring over a wide range of habitats from oligotrophic to hypernutrified, and appear to be expanding globally. Unlike many other ecosystems impacted by HABs, upwelling systems worldwide share a common set of physical parameters and are likely to respond similarly, regardless of locale. The Core Research Project on HABs in Upwelling Systems, a component of the scientific programme on the Global Ecology and Oceanography of Harmful Algal Blooms (GEOHAB), promotes a comparative approach to identify the similarities and differences in the manifestation of HAB events in these systems. As applied to the goals of this programme, molecular techniques are a powerful suite of tools for HAB species identification, for determining genetic similarity within morphologically indistinguishable species, and ultimately, for assessing spatial and temporal patterns in ecophysiological responses in these upwelling systems. Knowledge of HAB organisms will be enhanced by comparing and contrasting the responses of these organisms in similar upwelling regions. Here, we provide an update on the availability of molecular and genetic tools for comparative HAB programmes in upwelling systems, focusing on four broad applications: cell enumeration and identification, molecular phylogenetics, functional/comparative genomics, and applications of high throughput sequencing methods. We highlight the rapid evolution, the promise, and the potential pitfalls, of the molecular toolbox, focusing on specific examples of how scientists and resource managers currently apply these methods. Specific examples are developed using relevant case studies from the California, Benguela and Iberian systems. We summarise by providing a synthesis of future research directions and goals that would be particularly relevant to advancing the comparative method for HAB genetics with an emphasis on upwelling systems.