Stoneflies (Plecoptera)

Abstract

Executive Summary: Based on just over 12,000 records for the island of Ireland, the 20 species of stonefly (Plecoptera) on the Irish checklist were evaluated against the Red List criteria produced by the International Union for the Conservation of Nature (IUCN). This is the first time the threat status of the Irish Plecoptera has been assessed. Two species are deemed under threat of extinction. Protonemura praecox, was assessed as Critically Endangered and Capnia atraas Vulnerable. A third species, Perlodes mortoni, was deemed Regionally Extinct in Ireland as it has not been recorded for over 100 years. The remaining 17 species were all evaluated as Least Concern. The records used in this assessment cover the period 1890 to 2018 and have largely been derived from collections of nymphs, although many adult records are included. The threat status of two Red Listed species quite likely reflects increasing average temperatures associated with climate change.Other species confined to higher altitudes may become threatened in the near future as temperatures continue to rise. The threats that climate change, continuing organic pollution, habitat change and sedimentation pose to the Plecopterain Ireland should not be underestimated, with most species highly susceptible to one or more of these pressures. Habitat destruction and hydromorphological change (e.g. flood protection schemes) are likely to have had a significant influence on the present distribution of the Irish stoneflies and the impact of these pose continuing and significant threats. Lastly, the future recording of Plecoptera, and other aquatic insects, to species level must remain a priority. Reliable data are a pre-requisite for Red List assessments and atlases. However, it is of concern that fewer freshwater studies and surveys are producing species-level data. Unless this deficit is addressed, our ability to assess and understand trends in species distributions, and of Ireland’s freshwater biodiversity, will be much diminished.