The use of flow cytometric applications to measure the effects of PAHs on growth, membrane integrity, and relative lipid content of the benthic diatom, Nitzschia brevirostris

This laboratory study measured the direct effects of three polycyclic aromatic hydrocarbon (PAH) compounds (naphthalene, pyrene, and benzo(a)pyrene) upon cell growth, membrane integrity, and BODIPY-stained lipid fluorescence intensity of the benthic diatom Nitzschia brevirostris using flow cytometry as an analysis tool. Previous field and laboratory studies have reported reductions in algal populations following PAH exposure, but specific, functional responses of the microalgae to these pollutants could not be revealed by cell numbers alone. Using flow-cytometric measurements, we confirmed that maximal cell densities in PAH-exposed diatom cultures were significantly lower compared to controls; however, we also discovered increases in lipids and cells with compromised membranes in PAH-exposed cultures. These results highlight new tools for measuring the direct effects of organic pollutants upon the physiology of taxa comprising microphytobenthic communities important in estuarine food webs.