European regional assessment: Least Concern (LC)
EU 27 regional assessment: Least Concern (LC)

Caliaeschna microstigma is still to some extent common in most of its range. On a European scale, it is fairly locally common in the southern parts of the Balkan Peninsula, but becomes more rare and scarce further north. The species inhabits fast-flowing and shaded waters, a habitat type more and more threatened by droughts, water captures, forest destruction and climate change, at a lesser degree also by human settlements and forest fires. Due to these threats, a species decline might occur in the future, however, it will probably be less than 30% in a period of next ten years. It is therefore assessed as Least Concern in both Europe and the EU27 as it is not close to meeting the thresholds for a threatened category (apart from B2 as the AOO for EU27 is 1,948 km²). However, the development of the species' population trends should be monitored, and if a change in a more negative direction occurs, a different assessment in the future may possibly be relevant. More fieldwork is needed also to obtain information on its distribution, conservation status and the effects of climate change.

This species, which is a good indicator of the quality of streams and small rivers, should be included in the Annexes of the European Habitats Directive and also special areas of conservation delineated.

Caliaeschna microstigma is a largely Southwest Asian species that occurs from south-eastern Europe through Türkiye, the Levant, the southern Caucasus to north-western Iran near the border of Afghanistan (Boudot et al. 2021).

In Europe, its distribution is restricted to the Balkans, the Aegean islands and Cyprus (Kalkman and Jović 2015). In Greece, it is fairly common and widespread with the exception of some islands, including Crete, but occurs on Rhodes, Corfu and Lefkada in the Ionian Sea, North Aegean Islands (e.g. Thasos) and West Aegean Islands (e.g. Evia). It is also fairly common in Cyprus and Albania. In Bulgaria, it is widespread, but does not reach Romania. Along the eastern Adriatic, it is found as far north as Croatia, where it is confined to the southernmost part of the country. The species seems to be more widely distributed and also occurs in higher densities in Bosnia and Herzegovina, and especially in Montenegro (Vilenica et al. 2021) as well as in Greece. As dragonfly studies in southeastern Europe are still scarce, a further increase in the number of C. microstigma localities are predicted as the species is under-recorded in the Balkans at least. Its current extent of occurrence (EOO) covers an area of 886,398 km². Its area of occupancy (AOO) is 2,828 km² and in the EU27 its AOO is 1,948 km².

Even though there is not enough data to calculate population trends and no specific studies are dealing with local or regional population trends, C. microstigma is most likely under-recorded in southeastern Europe, where the species can often be fairly abundant. However, its populations are expected to decrease because of habitat degradation and climate change, although not severely in the next 10 years. Additional research on its distribution and population dynamics is needed.

Caliaeschna microstigma has a clear preference for unpolluted, swift flowing streams and small rivers with stony, pebble or gravel substrate that are at least partly shaded and where pools of calm water provide refuges for the larvae (Kalkman and Jović 2015, Kovács and Murányi 2013). Therefore, it is considered a good indicator of the quality of streams and small rivers. Larvae can be found among moss, leaf litter, submerged tree roots, but also under big boulders, stones and rocks in the stream bed or in cascades or waterfalls (Kovács and Murányi 2013, Breuer and Douma-Petridou 2000, Vilenica et al. 2021). In the western Balkans the species prefers karst springs, followed by fast-flowing, partially shaded streams, rivers, and sometimes even channels and waterfalls (Vilenica et al. 2021). Most of these habitats are characterised by well-oxygenated cold running water. Although C. microstigma was observed along a wide altitudinal gradient, from lowlands to mountainous areas, most European populations are found below 500 m a.s.l. In the western Balkans it is considered predominantly a lowland species, most often recorded at elevations below 200 m, with the highest confirmed reproduction at 925 m (Vilenica et al. 2021, Vinko et al. 2017). It is often found together with Cordulegaster species. Suitable habitats for C. microstigma do exist also in areas north of the species' presently known distribution. The species’ current absence and/or rarity in such areas is most probably caused by cold, harsh winters (Vilenica et al. 2021). Hence, climate change could lead to rising winter temperatures in northern latitudes and higher altitudes and may lead to an expansion of the species' range.

The main threats for habitat destruction are regulation of water flow, including spring capitation, dam and reservoir construction, and pollution from nearby settlements and agricultural areas. Removal of trees or forests on the banks of brooks and rivers can also lead to local extinction of the species. In the future, the increased demand for water and the increase of prolonged dry periods due to climate change will be an important threat. Due to rising temperatures, decreased precipitation and hydrologic alterations, in combination with an increase in frequency and intensity of extreme events (e.g., droughts), the species' habitat is facing drastic changes. Moreover, a series of ongoing and planned hydropower stations throughout the Balkans will create further habitat degradation. Threats are also caused by alterations of stream morphology through canalisation, changing substrate, gravel extraction, or concreting the riparian banks (Vilenica et al. 2021).

There is no trade or use of this species.

C. microstigma was proposed in the past to be included in the EU Habitats Directive as it is considered a good indicator of the quality of streams and small rivers (Kalkman et al. 2018). The species' habitat is threatened, although the species' current trend is suspected to be stable. However, its populations are expected to decrease in the future because of habitat degradation and climate change, hence species conservation is needed as C. microstigma is still potentially threatened both on European and EU27 level. Conservation measures should include the expansion of water treatment plants, improved watercourse management (less removal of vegetation and disturbance of sediments) as well as the preservation of good quality water resources. In areas that are embedded in the Natura 2000 network, changes in management plans should be made regarding the use of water. Catchment management plans should be drawn up, with particular attention to ecological flows, in accordance with the European Water Framework Directive (WFD CIS, 2015). This should mitigate or even prevent water abstraction for agricultural or domestic use from streams and rivers. Legislation for the sustainable use of water from springs and brooks needs to be made or fully implemented.

Monitoring is needed to better understand the ecology of this species and the potential impacts of climate change and to obtain relevant data for conservation management. Further research on the species' distribution is in need, also in order to assess population trends and to obtain a better overview of populations in protected areas, This would provide important information if additional protected areas or management plans are in need.

This species, which is a good indicator of the quality of streams and small rivers, should be included in the Annexes of the European Habitats Directive and also special areas of conservation should be delineated.