Macroinvertebrate frequency data for the RIVPACS III sites in Northern Ireland and some comparisons with equivalent data for Great Britain

Abstract

1. A total of 313 macroinvertebrate taxa were recorded from the 70 running-water sites in the River InVertebrate Prediction And Classification System (RIVPACS III) dataset for Northern Ireland, after the application of a standardization procedure to ensure that all samples were identified to the same taxonomic level. The listing includes a small number of oligochaetes not previously reported from Ireland. The frequency of occurrence of the 313 taxa within the Northern Ireland dataset is also presented. 2. The taxonomic composition and frequency of occurrence of taxa in the Northern Ireland dataset were then compared with the 614 site dataset for Great Britain, which included 637 taxa, and a 75 site subset within Britain at a similar latitude to Northern Ireland with 333 taxa. 3. The macroinvertebrate fauna of Northern Ireland is dominated by taxa recorded at the highest frequencies of occurrence in Britain. Some notable absences are highlighted and, in particular, a small number of lotic mayflies and stoneflies which are common in Great Britain. There is documentary evidence of the introduction by man of a number of non-insect taxa, either deliberately or by accident. 4. A detailed knowledge of the present composition of the macroinvertebrate fauna of running-water sites in Northern Ireland, and an active research programme on the potential for new colonists to pose a threat to native species, are important factors in the future conservation of the freshwater fauna. Copyright © 2000 John Wiley & Sons, Ltd.