miércoles, 26 de noviembre de 2014

Ireland Red List No. 6: Damselflies & Dragonflies (Odonata)

Ireland Red List No. 6: Damselflies & Dragonflies (Odonata)
Brian Nelson, Colm Ronayne and Robert Thompson

Nelson, B., Ronayne, C. & Thompson, R. (2011) Ireland Red List No.6: Damselflies & Dragonflies (Odonata). National Parks and Wildlife Service, Department of the Environment, Heritage and Local Government, Dublin, Ireland.

Based on almost 32,000 records for Ireland, the 24 species of resident damselfly and dragonfly (Odonata) are evaluated for their conservation status using International Union for the Conservation of Nature (IUCN) criteria (IUCN, 2001, 2003). Four (17%) of the Irish species are assessed as threatened, and one species as near threatened. The populations of all five species need to be thoroughly surveyed and monitoring programmes for each initiated. Causes of the decline in each species need to be determined, existing and possible threats identified, and protective measures introduced. The remaining species are all assessed as least concern.
The Irish odonate fauna is a limited one, reflecting the recent geological history of the island; its location off the western edge of the European continent; the climate, and the range of habitats present. Despite this, the fauna is not without interest and in particular when compared to that of Great Britain. The most interesting species of the Irish fauna is the Crescent or Irish Bluet Coenagrion lunulatum which is mainly a northern Eurasian species that is absent from Great Britain. The Irish population of the Robust Spreadwing Lestes dryas is also of interest because of its association with the turloughs of the western limestone.
Three of the threatened odonates, Northern Emerald Somatochlora arctica, Downy Emerald Cordulia aenea and Crescent Bluet Coenagrion lunulatum, are found in low nutrient status wetlands and the change brought about by enrichment of these habitats is regarded as the primary threat to these species. The decline of these should act as a warning of the negative trend in the state of these wetlands which are a distinctive feature of many Irish counties. These three are also predominantly northern species and the Irish populations lie at the southern edge of their ranges. In the long‐term the impact of climate change may be significant. Climate change may actually benefit the remaining threatened species, Small Bluetail Ischnura pumilio, and the near threatened Robust Spreadwing Lestes dryas, but the immediate threat to these species is habitat loss. Both these damselflies are dependent on specific hydrological conditions which are easily damaged and altered.

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