An alternative workflow for the extraction and study of testate amoebae (protist: Amoebozoa, Rhizaria, Stramenopiles) through vacuum filtering and grid-based low-vacuum scanning electron microscopy (SEM): Illustrated from scottish leaf litter

The extraction and study of testate amoebae from peat, leaf litter, soils and water samples, typically involves wet-sieving, followed by hand picking of material for examination by optical and scanning electron microscopy (SEM). Herein, an alternative workflow is described for the extraction of testate amoebae, that has successfully been applied for a range of sample substrates (leaf litter, mosses, liverworts, lichens, sands and gravels), as well as water samples, which involves vacuum filtration of testate amoebae suspended in water and the methodical analysis of the dried filter paper in a grid-like search pattern using SEM. Leaf litter from the Riccarton Campus of Heriot-Watt University is used here to illustrate the workflow. The method benefits from its ease of use and speed, observation of all size ranges of testate amoebae present, including partial samples, and the placing of the recorded material within the context of other mineralised micro-organisms, micro invertebrates, as well as the size and composition of any detrital grains present. The method is unlikely to introduce user bias, is of relatively low cost, ensures a lack of contamination, and facilitates the study of testate amoebae within their larger environmental context. Comparison with wet-sieved material gives comparable results, with differences controlled by the size of the final sieve mesh size.