Bacteria, cyanobacteria, protozoa and small eukaryotic phytoplankton are now known to be fundamental components of marine planktonic ecosystems (Azam et al., 1983; Sieburth, 1984). These organisms have high potential growth rates, are efficient converters of material and energy, and usually constitute most of the plankton biomass (Davis et al., 1985; Fuhrman et al., 1989). Their different trophic levels are often closely coupled. These characteristics require that experimental and sampling designs for studying the microbial populations incorporate appropriate (i.e., small) temporal and spatial scales. The corollary to this is that large numbers of samples must be taken. If these can be processed rapidly, sampling designs can be modified to existing conditions. Quantifying the abundance and biovolume of these microbial cells is difficult because these organisms are extremely small and cell biovolume is a cubic function of linear dimensions. These difficulties are major obstacles to developing realistic trophodynamic models.

Sieracki, M.E., and C.L. Viles. 1990. Color image-analyzed fluorescence microscopy: A new tool for marine microbial ecology. Oceanography 3(2):30–36, https://doi.org/10.5670/oceanog.1990.05.

This is an open access article made available under the terms of the Creative Commons Attribution 4.0 International License (https://creativecommons.org/licenses/by/4.0/), which permits use, sharing, adaptation, distribution, and reproduction in any medium or format as long as users cite the materials appropriately, provide a link to the Creative Commons license, and indicate the changes that were made to the original content. Images, animations, videos, or other third-party material used in articles are included in the Creative Commons license unless indicated otherwise in a credit line to the material. If the material is not included in the article’s Creative Commons license, users will need to obtain permission directly from the license holder to reproduce the material.