Nested cell strainers: An alternative method of preparing palynomorphs and charcoal

Centrifugation and sieving are essential techniques used in standard preparations of pollen and other palynological material. However, multiple centrifugation steps can potentially damage delicate palynomorphs and other microfossils, and the process of decanting after centrifugation can lead to loss of material. Traditional sieves often have a large surface area which makes manipulating smaller samples difficult and creates the need for potentially damaging techniques (e.g., sonication) to facilitate material through the sieve. We propose using stackable cell strainers as an alternative method for the preparation of pollen and charcoal samples. These sieves fit firmly on standard plastic 50 ml centrifuge tubes and special rings allow the attachment of disposable syringes for suction. We demonstrate that the results of using cell sieves are comparable or better than those of traditional methods. Pollen counts from nine Holocene sites using the cell strainers showed similar concentrations of major palynomorphs in comparison to counts of samples processed following traditional methods. Visual comparison and counts of delicate pollen morphotypes, such as Pinaceae and Poaceae grains, indicated that fewer grains were damaged when cell strainers were used. Macrocharcoal preparations using cell strainers showed consistently lower counts than samples prepared using traditional methods, which may reflect lower rates of fragmentation of fossil charcoal during preparation. Finally, we demonstrate that nested cell strainers are also effective in processing lithified material and isolating and staining pollen from herbarium samples.