On the use of instar information in the analysis of subfossil chironomid data

Head capsules of chironomids of the genera Chironomus, Glyptotendipes and M icrotendipes in two cores from Lough Neagh, Northern Ireland, were identifi ed to instar. The proportions of 3rd and 4th instars did not stay constant throughout the lengths of the cores and it is possible there was differenti al preservation of the instars. Plotting diagrams using only one instar cou ld give misleading information about the occurrence of a genus, while plott ing total number of head capsules may result in individuals being counted t wice. Counting the most numerous taxon at each level in the sediment avoids the latter problem while retaining maximum information about the fauna. No n-metric Multi-Dimensional Scaling ordination diagrams calculated using the different methods illustrate the similarity of plot obtained.