Last updated May 28, 2018 at 5:10 pm
Research inspired by famous Kon-Tiki Expedition.
Photo: iStock Dimitris66
Forms of toxin producing microalgae usually found attached to surfaces are moving into new areas of the ocean by hitchhiking on seaweed “rafts” in the East Australian Current, new research has found.
Inspired by reading Norwegian writer Thor Heyerdahl’s 1948 book The Kon-Tiki Expedition: By Raft Across the South Seas, a team from the University of Technology Sydney tested and confirmed this hypothesis during a 2015 voyage on the CSIRO Marine National Facility RV Investigator.
Among the thousands of microalgal species that inhabit our oceans some produce toxins harmful to human health. The range of some of these marine microorganisms is expanding but scientists have not be sure how this happens.
PhD candidate and lead author, Michaela Larsson, from the UTS Climate Change Cluster, said that during their voyage the researchers had
UTS researchers aboard the RV Investigator. Photo Michaela Larrson.
looked for “epibenthic dinoflagellates” – a group of microalgal species usually found associated with sediments or on the surface of seaweeds and seagrasses.
Cells not suspended in currents
“We’d already ruled out the likelihood that viable cells of these organisms could be dispersed suspended in ocean currents because an analysis of plankton samples collected over 50 years failed to reveal their presence,” she said.
The team collected drifting seaweed and seagrass fragments from the East Australian Current and identified the associated microalgal communities to see if epibenthic dinoflagellates could remain linked with these “rafts” once transported offshore.
Viable cells of potentially harmful dinoflagellates from the genera Coolia, Amphidinium and Prorocentrum were found associated with rafts, therefore revealing rafting as a potential vector for dispersal of these organisms.
Larsson said phylogenetic analyses had confirmed the presence of Coolia palmyrensis on a drifting Sargassum sp. raft, the first report of this potentially harmful epibenthic dinoflagellate species in temperate Australian waters. Further investigation is needed to confirm if viable cells of these organisms can be delivered to shallow coastal waters and successfully colonise new coastal habitats.
The researchers say managing the risk to human health from toxin producing microalgae will require monitoring their diversity and abundance as well as ecological research to understand whether their distribution is changing.
The paper published in the journal Marine Ecology Progress Series.
