The data below has been gathered during school visits. A typical collecting day consists of 4 sessions. 6 groups of children in each session collect from the water using nets with 1 mm mesh. These are sorted through in white trays and a selection of animals taken from the trays and put into smaller pots. Animals from all trays are used to compile a list for the day. Towards the end of the session, each group estimates the numbers of  particular animal types in their tray. The numbers shown below are intended to show  the contents of a typical tray from the sampling effort of  all visits for the years 2003 - 2005 and for each day visit for 2007 - 2008. No quantitative data was recorded in 2006.

 

Although there is considerable variation in the collecting effort and accuracy of each group, the number of repetitions does provide a degree of validity to the data, at least with respect to observing trends, and this is the main reason for gathering the data.