Who is MarCy?

MarCy™ is a world-wide collaboration of researchers with a focus on standardizing and improving flow cytometry for microbes and phyoplankton in the marine environment. The consortium works on new technological solutions that are evaluated in field trials across the globe. The group aims at standard protocols for the use of this technology and develops software that facilitates the comparison of data from different surveys. The group promotes this work by making it's designs and protocols available to the marine research community.

Why the special effort?

Flow cytometry is an exceptionally powerful technology for identifying and counting particles in suspension. The technique is mainly applied to mammalian cells in biomedical research. Mammalian cells are large, bright and can be labelled with well known chromatic agents. In contrast, the particles that matter in the ocean (microbes, phyto-plankton, organic debris, inert particles) are often very small and may have very dim, unusual and unexplored optical properties. While biomedical tests are carefully adjusted to render the measurements proportional to some biological characteristics, more often than not, results with marine organisms are not readily interpreted. To make sense out of real world samples, we need equipment that is better tuned and we need to improve our understanding of the non-linear optical properties of small biological particles.

The questions we work on:

• How best to quantify chlorophyll in individual particles?

• How many cells are in a known volume? What is the size distribution?

• What accessory pigments are present?

• How much DNA is present?

• How to interpret scatter and polarization signals from particles smaller than the wavelength of light.

Why are quantitative particle counts important for oceanography?

Phytoplankton harvests the energy that feeds the pyramid of life in the ocean. The large majority of photosynthetic organisms are too small to study with any technique except for flow cytometry. Quantitative flow cytometry allows us to collect a census of marine organisms and follow their behaviour and dynamics in response to environmental challenges.