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Lights, camera and action - all in one instrument: The FlowCAM

Wednesday, May 11th, 2016

Are the laborious days of sitting behind a microscope gone? Perhaps for plankton ecologists they are….

Last week we talked about microplankton and the experiment being conducted by Dr. Krause and his team on the impacts of oil and dispersant exposure on the microplankton community of the northern Gulf of Mexico. You may recall that microplankton are between 20 and 200 µm in size – that is 20 one thousandth of a millimeter or one millionth of a meter. Pretty small! Organisms this small are difficult to see and study using standard microscopes. They have to be prepared using a special fixative and slide mounting techniques, making it time consuming and difficult to study many organisms and samples. There are electron microscopes, but they too require special preparation methods that are costly, again making it difficult to study many samples.

An alternative approach would be to study and measure what the microplankton are doing. For example, scientists could measure the rate of metabolism of a community by isolating it for a short period of time and measuring the production of a metabolic product or the rate of disappearance of a metabolic resource (a good example would be oxygen evolution or consumption). While this approach may tell you how the whole community is functioning, it does not identify who (i.e. what species) is contributing to that rate. This approach has been called the black box approach and has been successful in many ecological studies.

Obviously, a better understanding would involve measuring both who is present in the sample and what they are doing (or how much they are contributing to the rate, from the example above). What we know, especially about the ocean, is determined in part by how we know it. The development of new technologies, such as the light (aka. standard) microscope followed by the electron microscope or the sounding (aka. lead) line followed by sonar, has given us new insight in science. In the study of microplankton, the FlowCAM is that new tool giving novel insight to plankton ecologists.

The FlowCAM is a patented digital imaging system that couples particle imaging with automatic pattern recognition for a stream of fluid moving through the instrument. As the fluid moves through the FlowCAM system, individual particles in the fluid are photographed. The pictures are then compared to known particle images in the database of the instrument, from which species and abundance of those species can be determined.

FlowCAM images
Example of a typical output from a sample passed through the FlowCAM. Photo credit: J. Krause

Various characteristics of particles, such as size and volume, can also be measured from the image. And the FlowCam system can do all of this rapidly – up to 10,000 images per minute! This remarkable system has proven to be versatile as it has been used to study climate change using pollen grains, to look for larvae of invasive mussels and crabs, to investigate harmful algal blooms and even used to find contamination of pharmaceutical products. In the video below Dr. Krause explains the use of the FlowCAM as one of the ways he and his colleagues are studying the effects of oil and dispersant on microplankton diversity and resilience. Keep up with us on our News and Research pages for results of his team’s current experiment.