Diatom-bacteria interactions: deciphering impacts on algal bloom regulation and toxicity

Marine phytoplankton are vital in regulating our global climate, contributing almost half of the biosphere's net primary production. Diatoms are one of the most important phytoplankton groups, generating as much organic carbon as all terrestrial rainforests combined. Diatoms form spatially extensive blooms that exert global-scale influences on biogeochemical cycles and underpin ecosystems. Due to the release of harmful toxins, some diatom blooms can also have a negative impact on marine ecosystems and fisheries.

The biotic interactions of diatoms with predators, parasites, competitors and symbionts, can profoundly influence natural diatom populations, and are an important factor regulating bloom dynamics and potential toxicity. Despite the clear importance of such interactions for diatom ecology and marine ecosystem functioning, little is known about the mechanisms diatoms employ to i) recognise and respond to other microbes, or ii) regulate production of harmful toxins. These represents important knowledge gaps that need to be addressed, in order to better understand factors governing diatom bloom formation and toxicity.