Abstract
Semi-natural wet meadows are threatened by drainage, the abandonment of traditional management and climate change. The large blue butterflies Maculinea teleius and M. nausithous are flagship species associated with wet meadows and are the targets of many conservation programmes. However, there is little knowledge on the impact of natural catastrophes, such as floods, on the persistence of these butterflies. In our study we tested how a flood that resulted in the temporary inundation of meadows affected populations of M. teleius and M. nausithous. Studies were conducted in two consecutive seasons of 2009 (with ‘normal’ weather) and 2010 (with extreme rainfall and a consequent flood in May) in a wet meadow complex located in the Vistula River valley in southern Poland. In both years the abundance of adults was estimated for each local habitat patch (n = 55) within sympatric metapopulations of both species. Additionally, in June 2010, i.e. directly after the flood and shortly before the flight period, a total of 754 Myrmica ant nests in 10 habitat patches (6 inundated vs. 4 not inundated) were checked for the presence of Maculinea larvae and pupae. We found no impact of inundation on year-to-year changes in adult population sizes. The probability of occurrence of Maculinea larvae and pupae in ant nests was higher in temporarily inundated meadows. Our results indicate that temporary inundation occurring after long-term downpours does not negatively affect the investigated species even during the larval period in ant nests at ground level. This provides an argument against drainage works in wet meadows with Maculinea butterflies.
Highlights
Most recent climate change models predict that extreme weather events such as flooding or long periods of drought will become more frequent in the near future (Cowie 2007; Fronzek et al 2012)
Our results indicate that temporary inundation occurring after long-term downpours does not negatively affect the investigated species even during the larval period in ant nests at ground level
Our results suggest that there was no negative impact of the flood in the spring 2010 on the investigated local populations of Maculinea butterflies
Summary
Most recent climate change models predict that extreme weather events such as flooding or long periods of drought will become more frequent in the near future (Cowie 2007; Fronzek et al 2012). Wet meadows are an example of semi-natural habitats characterised by high biotic diversity, including rare butterfly species, and are vulnerable to environmental changes (Maes and Van Dyck 2001; Robinson and Sutherland 2002; Saarinen et al 2003; Van Buskirk and Willi 2004). Butterflies, with their typically specialised and rather sedentary larval stages, are sensitive to the condition of their habitats and this makes them good indicators of ecosystem changes. Studies on several wet meadow species revealed differing responses to floods. The immature life stage of overwintering butterflies may be key to survival during flooding: while non-mobile Lycaena xanthoides eggs (Severns et al 2006) or Neptis rivularis hibernacula (Konvicka et al 2002) experience relatively high mortality during flooding, Lycaena dispar batavus second instar larvae do not (Webb and Pullin 1998)
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