Marine microbes are the most abundant organisms in the oceans and play a critical role in fixing carbon dioxide and in nutrient cycling which serves as the bedrock to the food web. Despite this fundamental role, surveying microbial communities throughout the world’s oceans has long been an extremely expensive discipline, requiring ship time for sample collection and thereby economically constraining the number of samples collected. Large scale modeling of global biogeochemical cycles requires the collection of high-density data, both temporally and spatially in a cost-effective way.

With a combination of new technologies, appropriate laboratory protocols and strategic operational partnerships we have shown that it is possible to significantly broaden our knowledge base of the ocean by engaging thousands of private ocean-going vessels that are cruising around the world’s oceans every day. This can be achieved by equipping sailing vessels with small automated sampling devices that take a variety of biological and chemical measurements.

We established the basic protocol  during the Indigo V Indian Ocean Concept Expedition, sailing from Cape Town to Singapore, highlighting opportunities of this approach and developing yacht-adapted instrumentation (1).

The analysis of the metagenomic and metatranscriptomic datasets from our pilot expedition and the first wave of ‘citizen oceanographers’ has identified biogeographic patterns in microbial community composition consistent with long studied Longhurst ocean provinces, which are defined by primary productivity and thermohaline properties of ocean currents.

I will present insights gleamed from our work thus far, including mechanisms of top-down (grazing and predation) and bottom-up (resource availability) factors affecting the structure and function of microbial communities in diverse marine habitats. For example, biogeographically unique samples from within a pristine coral atoll showed an increase in the expression of genes related to photosynthesis and nutrient cycling associated with the bottom-up control of bacterial populations, but a five-fold increase in the expression of viral proteins within the lagoon, indicated a concomitant top-down control of bacterial dynamics by phages.