Taxonomic Notes
Gomphus vulgatissimus is rather similar to G. schneiderii and the latter is sometimes considered as a subspecies of the former, with which it can be easily confused. Both taxa either overlap and hybridise or are connected through clinal variation by intermediate forms, so that the geographic limit between them cannot be traced with certainty. Some intermediates have even been described under G. schneideri helladicus Buchholz, 1954. Due to this complexity, information on distribution in parts of the Balkan Peninsula is unclear and genetic studies will be needed to clarify the situation in this area.
Justification
European regional assessment: Least Concern (LC)
EU 27 regional assessment: Least Concern (LC)
Gomphus vulgatissimus have recovered since the 1990s, probably because of increased water quality and more natural management of river systems. It was expected to increase further due to ongoing climate change, but the current situation is somewhat difficult to interpret as it can be regionally or locally abundant, while elsewhere show an ongoing reduction. It is threatened in Austria, Belgium, the Czech Republic, Denmark, France, Germany, Luxembourg, Slovenia, Spain, Switzerland, and the UK. Distribution trends indicate a decline in some areas, but they are positive in others, and it is expanding northwards. Some of the historical threats to the species have ceased or lessened, especially water pollution, but it is now threatened by several factors in combination such as drought, water extraction and canalisation that all are amplified by climate change. Although it is declining in some regions, the negative trend is more modest than the positive one. The species is therefore still assessed as Least Concern. However, the species' situation could quickly change for the worse if the threats do not cease, so the development should be monitored, and if a change in a more negative direction occurs, a different assessment in the future may be relevant.
Geographic Range Information
G. vulgatissimus is a western Palaearctic species with a main distribution in Europe, from Wales in the west to the Ural Mountains in the east. Beyond the Urals, the range extends further into Asia as far as the Altai. The species is absent from Ireland and Scotland, large parts of the Iberian Peninsula and most of the islands in the Mediterranean but is otherwise widespread in Europe. It overlaps with Gomphus schneiderii in the Balkan Peninsula and in the Caucasus, which means that the distribution limit of both species is currently poorly defined. Where the species meet, it is next to impossible to tell them apart morphologically, so more studies are required to gain definitive knowledge of their distribution and situation. G. vulgatissimus has during the last decades extended its range in the British Isles and in Sweden, which is attributed to global warming (Billqvist et al. 2019, Bodout and Jović 2015, Boudot et al. 2015).
Population Information
G. vulgatissimus is widespread over large parts of western, central, and eastern Europe. In some regions it recovered during the 2000s’ from a long decline in step with better water quality and a more natural management of river systems. It re-appeared in some areas and regionally expanded its distribution. The current situation is somewhat difficult to interpret. It was expected to increase further due to ongoing climate change, but the expansion now seems to be more or less limited to its northern range where it is expanding in the UK and Sweden (Billqvist et al. 2019, Boudot et al. 2015). It also shows positive trends in countries such as the Czech Republic and the Netherlands, but tends to decline in others, such as in France and Lithuania. In the south, the species has a more fragmented presence and is expected to decline due to habitat degradation through climate change.
Habitat and Ecology Information
G. vulgatissimus is found in small to large slow-flowing watercourses with good water quality and sandy to silty bottoms. It can sometimes also be found in lakes and gravel pits, especially those with shallow sandy beaches. The species is most common in a varied semi-open landscape. It is often completely absent along watercourses in large, open agricultural landscapes, which may be due to poorer water quality rather than an unsuitable environment in general. It also appears to be absent or rare in watercourses that mostly flow through closed forests (Billqvist et al. 2019).
G. vulgatissimus is found at and along watercourses, where the male is often easy to see. He patrols low over water surfaces and makes short excursions to chase away males that come too close. The male often returns to the same resting places with a view of the territory. Favourite spots consist of rocks, branches, exposed sandbanks, and piers in and along the water. Females and young males are often seen very far, up to several kilometres, from water, but they are more often seen adjacent to watercourses in clearings, shrubbery, or edge zones. Mating also takes place there. Like other Gomphids, it likes to perch directly on the ground in gaps between tufts of grass, but also high up in trees where it can be very difficult to see. The eggs are laid in calm parts of watercourses where the larvae live in shallow silt bottoms. Larval development lasts two to four years, occasionally only one year, depending on latitude and type of habitat. They leave the water in sync, which means that virtually an entire population leaves the aquatic life at the same time. The exuviae are found on plants or rocks close to the watercourses or a bit higher on adjacent trees (Billqvist et al. 2019, Richter et al. 2008).
Threats Information
G. vulgatissimus is threatened in Austria, Belgium, the Czech Republic, Denmark, France, Germany, Luxembourg, Slovenia, Spain, Switzerland, and the UK. Some of the historical threats have ceased or lessened, especially water pollution, but locally a general degradation of water quality might still be an issue for riverine species (Boudot & Dommanget 2015). Canalisation of water systems still poses a threat, as it causes high fluctuations of water levels and seasonal droughts. Restoration of canalised streams can however make them suitable again and these can quickly be recolonised. In some river systems waves caused by large boats might lead to an increased mortality of emerging adults and damage to riverbanks (Kalkman and Ambrus 2015).
Introduction of invasive crayfish may also be a threat as they have on some other riverine species (Boudot and Dommanget 2015). As shown during the last couple of years even large rivers can be subject to drought during increasingly hot summers. Recurring and increasingly severe and longer droughts are a major reason why riverine species are decreasing. The drought is partly due to climate change but is often worsened by an ever-increasing withdrawal of water for human use and irrigation. Lower water levels mean higher water temperatures, which changes pH values, nutrient content, and species composition. Higher water temperatures lead to a lower oxygen availability for the larvae which leads to higher mortality and changes in larval development and flight period. In the past, species has been able to re-immigrate to places that have dried out during certain years, but as droughts return more and more often and more severely, there are fewer suitable sites to disperse to and from (Boudot 2010, Kalkman and Ambrus 2015).
Use and Trade Information
There is no trade or use of this species.
Conservation Actions Information
Local conservation measures should include 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 can be made regarding 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. Control of river structures and perhaps of invasive species throughout the species' range are needed.