Laboratory preparation
2) Removal of excess water and macro remains
The most straightforward way to remove excess water and macro remains is by sieving and filtering. Sieve first through an ordinary kitchen sieve, at the same time, removing any small rodents, frogs and insects, and then through a 0.25 mm mesh, rinsing any animals and plant macros with distilled water. A semi-quantitative record should be kept of the number and identity of the animals and plant macros. Ideally the plant macros should be stored and fully identified for possible related research. After sieving, filter the whole of the trap contents, including any rinsing water, using a suction funnel and a filter paper (e.g. 11cm q aschefreie Rundfilter MN 640 w, Art. - Nr. 202 011 from Macherey-Nagel Gmblt & Co. KG ) which will dissolve in acetolysis mixture (Bonny 1976). This procedure is particularly efficient where large quantaties of liquid are involved and/or where saccate pollen grains, which show a tendancy to float on the surface of the water, are abundant (Hicks and Hyvärinen, 1986).
In a few cases the contents of the trap may be suffiently dirty to clog up the pores in the filter paper. In such cases an alternative method is to centrifuge. It is then also advisable to let the trap contents stand for at least two months in a cool room so that saccate grains become saturated and the pollen as a whole sinks to the bottom of the container. After this it is often possible to siphon off excess water leaving only 0.5 l for centrifugation (checking first that the surface water is indeed pollen free by looking at a sub-sample under the microscope).
Whichever method is employed it is essential to avoid losing any pollen.