Senior research scientist and director of the Center for Aquatic Cytometry at Bigelow Laboratory for Ocean Sciences, Nicole Poulton, gave a riveting lecture at the Opera House in Boothbay Harbor on the hidden wonders of the ocean as viewed through the window of flow cytometry. On July 23, before an audience of about 130, Poulton presented “Flow Cytometry – FC: The Microscopic Wonders in a Drop of Sea Water,” offering a glimpse into the microscopic life teeming within our oceans.
Poulton joined Bigelow in 2001 after completing her Ph.D. in biological oceanography from MIT and Woods Hole Oceanographic Institution Joint Program and shared her lifelong fascination with aquatic ecosystems. She spoke about how her interest was first piqued by her childhood experiences next to Lake Michigan and how moving to the South Pacific opened her eyes further to its enormity. “A single drop of ocean water on a slide is full of life,” she said, explaining that in just one droplet, there can be 50,000 to 500,000 bacteria and viruses, 500 to 5,000 pieces of phytoplankton, and one to five small zooplankton.
One of these techniques is flow cytometry, which involves the process of laser light detection and analysis of microscopic particles in water. Truly speaking, this revolutionized the study of these tiny organisms. BLOS was a pioneer for the use of FC to examine and count phytoplankton, thanks to the works of co-founder Clarice Yentsch. This opened a huge array of research and created the first center devoted to FC in aquatic sciences.
FC can also be used to identify and characterize phytoplankton with pigments by adding DNA-binding dyes and probes. This rapid method, possibly analyzing 1,000 to 100,000 particles per second, is very useful in environmental and biomedical research applications. Bigelow’s innovation continued to push FC to new heights by developing FlowCAM, an imaging-in-flow system that enables the automatic analysis of marine phytoplankton—hitherto a very time-consuming process done manually.
Poulton presented a video showing the speed at which the laser prompts the camera to take pictures, set for fluorescence and size detection. She said she hopes 50 years from now, using machine learning algorithms with AI, all microbes will be indexed and identified in real-time, which will create a better understanding of their density and distribution.
Speaking of the future, Poulton paid much attention to the continuous development of FC and its growing potential. One remarkable discovery given the benefit of FC is Prochlorococcus, Earth’s smallest and most common photosynthetic organism, accounting for about 20% of the oxygen we breathe. This marine cyanobacterium was discovered by Penny Chisholm at MIT in 1988 and is estimated to number in the billions of billions in the ocean.
Since it acquired its first FC device in the early 1980s, BLOS has hosted dozens of FC workshops for scientists. Poulton herself has sampled seawater weekly or bi-weekly at McKown Point since 2001 and represents the time series that scientists had leveraged in putting in changes within the food web of the Gulf of Maine, predator-prey dynamics, and phenology shifts.
Also, nutrient flux from the lower ocean to the upper 200 meters is being measured with the help of a NASA satellite launched in February, for which the FC would play a significant role in validating the satellite data that would be produced. Poulton collaborates with colleagues in using FC for imaging, sorting, and isolating aquatic organisms for further analyses, and also for developing tools for counting and measuring microplastics.
Poulton’s lecture will be live-streamed on BLOS’s YouTube channel and is part of a series sponsored by HM Payson. It continues on July 30 with senior research scientist Ramunas Stepanauskas presenting “Single Cell Genomics: Understanding the Ocean’s Potential, One Cell at a Time,” and concludes on August 6 with “Satellite Oceanography: Unlocking Insights by Analyzing the Big Picture,” by senior research scientist Catherine Mitchell. Space is limited and free registration is required.
The ocean acts as the breath of life in the form of oxygen and biodiversity and is itself an emerging frontier of science. It was captured from Poulton’s lecture that in the microscopic wonders within a drop of seawater lies much to learn and save our planet from challenges to its health and future.