Turbulence, a key component of flow regimes in aquatic ecosystems, affects planktonic organisms over a wide range of scales. We designed a computer controlled instrument to generate a turbulent field with vertically oscillating grids. This instrument produces isotropic microturbulence in a range that mimics natural values. We ran growth experiments in TurboGen with three ecologically relevant phylogenetically distant species Pseudo-nitzschia multistriata, Thalassiosira rotula and Chaetoceros decipiens, characterised by three different chain formation modes. P. multistriata produces chains by overlapping cell apices; in T. rotula adjacent cells are connected via chitin threads; C. decipiens cells hook each other through frustule processes called setae. Chain composition, the frequency of each chain length class expressed in number of cells per chain, was compared between turbulence-exposed cells and controls. Different outcomes were observed: P. multistriata did not show any modifications when exposed to turbulence, the other two responded by modifying the chain spectra in presence of turbulence. The experiments were run in triplicate and statistical tests confirmed significance of the results. Chain formation in diatoms has been proposed to be a solution to sinking and molecular diffusion of nutrients in the boundary layer. There are evidences that the process of chain formation is regulated by biotic stimuli, our results indicate that it can also be regulated by an abiotic factor: microscale turbulence. More thorough investigation with a transcriptomics approach will identify the genes involved in sensing and responding to turbulence in this class of unicellular algae

Aquatic Sciences Meeting, Aquatic Sciences: Global And Regional Perspectives - North Meets South, 22-27 February 2015, Granada, Spain

Peer Reviewed