Genomic evidence for global ocean plankton biogeography shaped by large-scale current systems.

Biogeographical studies have traditionally focused on readily visible organisms, but recent technological advances are enabling analyses of the large-scale distribution of microscopic organisms, whose biogeographical patterns have long been debated. Here we assessed the global structure of plankton geography and its relation to the biological, chemical, and physical context of the ocean (the 'seascape') by analyzing metagenomes of plankton communities sampled across oceans during the Oceans expedition, in light of environmental data and ocean current transport. Using a consistent approach across organismal sizes that provides unprecedented resolution to measure changes in genomic composition between communities, we report a pan-ocean, size-dependent plankton biogeography overlying regional heterogeneity.

Global drivers of eukaryotic plankton biogeography in the sunlit ocean.

Eukaryotic plankton are a core component of marine ecosystems with exceptional taxonomic and ecological diversity, yet how their ecology interacts with the environment to drive global distribution patterns is poorly understood. In this work, we use Oceans metabarcoding data, which cover all major ocean basins, combined with a probabilistic model of taxon co-occurrence to compare the biogeography of 70 major groups of eukaryotic plankton. We uncover two main axes of biogeographic variation.

Insights on the drivers of genetic divergence in the European anchovy.

Anchovies represent the largest world's marine fish catches and the current threats on their populations impose a sustainable exploitment based on sound scientific information. In the European anchovy (Engraulis encrasicolus), the existence of several populations has been proposed but a global view is missing. Using a multidisciplinary approach, here we assessed the divergence among different ecotypes and its possible causes.

TURBOGEN: Computer-controlled vertically oscillating grid system for small-scale turbulence studies on plankton.

In recent years, there has been a renewed interest in the impact of turbulence on aquatic organisms. In response to this interest, a novel instrument has been constructed, TURBOGEN, that generates turbulence in water volumes up to 13 l. TURBOGEN is fully computer controlled, thus, allowing for a high level of reproducibility and for variations of the intensity and characteristics of turbulence during the experiment.

Sensitivity of the rate of nutrient uptake by chemotactic bacteria to physical and biological parameters in a turbulent environment.

In this study, we use direct numerical simulations (DNS) to investigate the response of chemotactic bacteria to an isolated patch of chemoattractant in a turbulent environment. Previous work has shown that by stirring nutrients that are chemoattractants into a network of thin, elongated filaments, turbulence directly influences the rate at which chemotactic bacteria consume nutrients. However, the quantitative outcome of this process is influenced by a host of physical and biological factors, and many of these remain unexplored.