Development of a scanning confocal laser microscopic technique to examine the structure and composition of marine snow

A technique was developed to image marine snow particles by scanning confocal laser microscopy (SCLM). This method allows structural and compositional characterization of fully hydrated marine snow particles with minimal disruption of the particle structure. High specificity fluorescent stains petmitted sequential imaging of selected polysaccharides (concanavalin A: specific for mannose and glucose polymers), proteins [5‐(4,6‐dichlorotriazin‐2‐yl) aminofluorescein], and DNA (propidium iodide). Chl a autofluorescence can also be imaged. SCLM produced optical slices of marine snow particles that were suited for a number of image‐processing applications. These applications include high‐resolution fluorescently derived optical slices and composite images produced from combined optical slices. Initial observations suggest that marine snow particles found in the oligotrophic Pacific Ocean vary in composition and structure. Variations in polysaccharide and protein composition of marine snow particles may be related to particle morphology. When combined with other conventional analysis, such as epifluorescent and electron microscopy, LSCM can provide important contributions to characterizing composition and structure of marine snow.