Enter the Unseen World of Microbes [ICESCAPE]

Dr. Kevin Arrigo is a Professor in the Department of Environmental Earth System Science at Stanford University. He is the Chief Scientist for NASA’s ICESCAPE (Impact of Climate change on the Eco-Systems and Chemistry of the Arctic Pacific Environment) mission this summer onboard US Coast Guard Cutter HEALY.

“What on earth is that?” I ask as the pictures flash by on the video screen (the fearsome little creature I had seen on the screen turned out to be some kind of ciliated protozoan – more correctly called a “protist”). I’m gazing at the business end of the Imaging FlowCytobot, an instrument that not only counts all of the microbe cells in a small sample of water, it takes pictures of every one.

“This is the first time an Imaging Flow Cytometer has been taken out on a ship like this on a long, comprehensive survey,” says Dr. Sam Laney (Woods Hole Oceanographic Institution).

Many biologists gauge the abundance of single celled organisms such as phytoplankton and protists there are in a piece of ocean by filtering a half-gallon or so of water onto little white filters. Then we put those filters into an instrument like an elemental analyzer and measure the amount of carbon, nitrogen, chlorophyll, or whatever interests us. But we never get a good look at what that green or brown goo that collects on our filter is really made of.

With the Imaging FlowCytobot, Sam can not only get a clear picture of what kinds of bugs are in our sample, he can see how healthy they are and how biologically rich the ecosystem is. The FlowCytobot sips a sample of water and pushes that water through a little tube. When a laser detects a particle, the instrument counts it and a camera takes its picture. Usually the particle is a microbe but occasionally it’s a minuscule particle of dead stuff, much like the dust that drifts slowly in the breeze.

If the sample has lots of big, fat phytoplankton, you can be sure that the ecosystem is healthy and “blooming”, much like your garden blooms in springtime. If most of the cells in the sample are small and round, conditions are probably not quite right for a bona fide phytoplankton bloom. But if the sample is filled with dead particles or empty phytoplankton cells, it’s a sure sign that the bloom has run out of gas.

Each tiny sample of seawater has an important story to tell, and the Imaging FlowCytobot can translate that story into a language we can easily understand. And it’s really cool to watch!