Floating marine species and objects can drift from one area in the surface ocean to any other spot across the globe in less than a decade, finds a new study published in Nature Communicationsby Nereus Program alumnus James Watson, currently a research scientist at Stockholm Resilience Centre.

“Looking at the average quickest time it takes to go from any place in the ocean to any other place in the ocean, it’s about ten years,” says Watson. “For us, that was incredibly surprising. If you’re an oceanographer, you get taught during your first oceanography course that it takes about a thousand years for water to travel around all the oceans. So this ten year time scale was incredibly surprising and very short.”

The researchers used a computer model to specifically look at phytoplankton – microscopic organisms that live on the surface layer of water, obtaining energy through photosynthesis. Unlike other marine species, phytoplankton do not swim or self propel, so their movement is entirely reliant on ocean currents.

“We quantified how quickly things can go from one place in the surface ocean to another. We did this by going to particular places in the ocean and essentially dumping in tennis balls, which float and get moved around by ocean currents, and then tracking where they went,” says Watson. “Now we didn’t just go to a few places and dump in a few tennis balls, we dumped in 50 billion tennis balls. And we didn’t do this in the real ocean, because that would have been an environmental catastrophe, we did it in a simulated ocean, one that I ran on my computer.”