The UK / Ireland diatom ring test
Bowburn Consultancy administers an annual intercalibration exercise for freshwater diatom analysts in the UK and Ireland. Members of statutory agencies in both countries who are involved in ecological assessments participate, along with consultants, contractors and university researchers. The scheme involves five slides per year, sent out at roughly two month intervals for participants to analyse.
A group of experienced diatomists also analyse each slide and the mean TDI / LTDI value from their analyses provides the ‘target’. Other participants should achieve a result within 7 TDI units or 6 LTDI units (values derived from research during the DARES and DALES projects). The most abundant taxa on each slide are then photographed by a member of the expert panel and the images compiled into a report that is sent to all participants. This means that the ring test does not just give a quantitative measure of ‘performance’, but the slides plus reports build, over time, into a useful laboratory reference collection.
More details of the exercise are given in this paper: