European regional assessment: Vulnerable (VU)
EU 27 regional assessment: Vulnerable (VU)

Sympetrum depressiusculum is generally rare, has a patchy distribution and has shown a strong decline throughout most of its European range. It is estimated that this decline has been over 30% in the last ten years. The species is therefore assessed as Vulnerable on a European scale, even if climate predictions for the near future are absolutely not favourable (increased desiccation of ponds in late spring and early summer), and changing practices in aquaculture (fish breeding and stocking) and agriculture may lead to a further decrease and loss of suitable habitat. The species is assessed as Vulnerable (A2ac+3c+4c) for both Europe and for the EU27 Member States.

Sympetrum depressiusculum ranges from the Atlantic coast in Europe to the Urals in European Russia (Boudot et al. 2021). The European range covers central, eastern and southeastern Europe. The species has a patchy distribution and there are large areas within its main range where it is rare or absent (Kalkman and Conze 2015). A strong decline has taken place nearly everywhere from the second half of the 20th century onwards. Strong declines and even regional extinctions have resulted in the species becoming very rare and is assessed as threatened on several national Red Lists (Austria, Belgium, Croatia, Czechia, Germany, France, Italy, the Netherlands, Slovenia, Slovakia and Switzerland). The global range extends eastwards from Europe to the Pacific coast of Asia but is uncommon in large parts of its range (Boudot et al. 2021).

The Spotted Darter is scarce throughout its European range and population numbers have dropped in many areas in Europe. In the past the species was locally very abundant. In Belgium, France, Germany, and Italy, the number of sites and populations has decreased by more than 50% over the last decade (Ott et al. 2015, UICN France et al. 2016, De Knijf et al. 2021). Lesser declines have also been observed in the Balkans and other countries in Central Europe such as Austria and Switzerland. The species is assessed as threatened on several national Red Lists (Austria, Belgium, Croatia, Czechia, Germany, France, Italy, the Netherlands, Slovenia, Slovakia and Switzerland). An overall population decline of at least 30% in Europe during the last decade is suspected to have taken place.

The species shows strong regional differences in habitat preferences. The key factor seems to be that it needs unshaded, shallow waters that can heat up very fast. Typically the waters become dry towards the end of the summer and are flooded again next spring. Those situations can be found at the borders of large lakes and in marshes. These kinds of situations are also found in fishponds where the water level is manipulated for fish harvest. Although S. depressiusculum did lay eggs in abundance in rice fields, it seems that they do not reproduce there successfully, at least not in their current conditions.

Major threats to this species are changes in fish aquaculture (especially carp rearing) and the increased stocking of ponds for angling in northern and central Europe, which has led to changes and the destruction of its habitat. As a consequence of this habitat loss, there is higher larval competition with other dragonfly species and predation by fish. A second major cause is the drying up of marshlands and wetlands in central and eastern Europe due to climate change. This is especially the case if desiccation occurs in late spring (May and June) before the larvae are able to emerge.

This species is not used.

Considering the relatively low number of strong subpopulations in most countries it is advisable that for each of these, their conservation status is determined and, if necessary, management plans are developed and implemented. Protection of reproduction sites is absolutely needed, preventing the intensive use of ponds for angling. A thorough regulation of water management regimes should be in place at those localities where populations occur. The species merits to be listed on the Annexes of the European Habitats Directive. A monitoring programme across European countries is needed to obtain an accurate overview of population trends for S. depressiusculum.