A Detailed Atlas of the Dragonflies of the Brussels-Capital Region

Beautiful Demoiselle Calopteryx virgo, Auderghem - Parc Seny, 23 May 2018 © Bernard Pasau
10/05/2019
A Detailed Atlas of the Dragonflies of the Brussels-Capital Region
post by
Kelle Moreau

Because of their specific life cycle, dragonflies are very good indicators of the quality of humid environments. The study of changes in the odonatofauna can therefore be of use when monitoring the quality of ponds and watercourses. Such information can also be used to formulate management advice. The Royal Belgian Institute of Natural Sciences and Gomphus (working group of Les Naturalistes belges) therefore joined forces to obtain an overview of the distribution and number evolution of the dragonflies of the Brussels-Capital Region, using data collected by civil scientists.

The clearly visible identification characteristics of the adult individuals (size, colour, etc.), their general attractiveness, and the limited number of species (currently about 45-50 in the Brussels-Capital Region), make dragonflies a species group that can be recognised relatively easily with the naked eye or binoculars, without having to catch them in the process. Consequently, a large number of observations of this group, collected by volunteers and provided with very precise locations, can be found in the database of waarnemingen.be/observations.be. These data could also be valorised for use by managers and scientists.

Quality Indicators

"Among other things, their long life span in the larval stage, high position in the food web and sensitivity to chemical water quality, make dragonflies good bioindicators of the state of aquatic systems and the semi-natural zones that surround them. René-Marie Lafontaine, researcher at the Conservation Biology Unit of our institute, explains. « The odonatofauna (all of the dragonflies in a given area) is therefore an important tool for the bioevaluation of wetlands, and the study of changes in the odonatofauna can be very useful for the monitoring of the biological, physicochemical and hydromorphological quality of water bodies and watercourses. »

By putting the collected data in a management context, they can be used to define general management measures and to evaluate the impact of the management of wetlands on the odonatofauna, and indirectly on the state of ecosystems. And thus to orient and improve future management work in the longer term.

Distribution Maps

Although the Brussels-Capital Region was treated (5x5 km² quadrants) in 'The dragonflies of Belgium (2006)', an update and refinement of the geographical resolution (1x1 km² quadrants) was desirable in order to be more useful to evaluate the current management. For this reason, this atlas project was launched at the beginning of 2016. In order to be sufficiently complete, the data from waarnemingen.be/observations.be were supplemented with data collected within a coordinated data collection over four field seasons (2016-2019), following a standardised protocol. In this way, between 95 (regular suppliers of observations) and 200 observers (occasional suppliers) were involved in the work. All data were aggregated and processed in order to produce 1x1 km² distribution maps for all identified types of distribution. « The main purpose of these preliminary maps is to identify areas that were little or not visited so that a higher inventory effort can be planned there, but they are also powerful visual tools that help to persuade civil scientists to complete the observation network. » explains Sophie Marée, 2nd year Master of Biology student (UCL- UNamur) and intern at the Conservation Biology Unit.

The last inventory season has just begun. The collaborators visit their areas from the end of April (beginning of the flight period of the earliest species) to the end of October. The ultimate goal of this project is the publication of an updated atlas that is as accurate as possible, and the formulation of advice for an optimal management of the wetlands. In the meantime, the preliminary maps (situation until the end of 2018) can be consulted here.

 

The 'Atlas of the dragonflies of the Brussels-Capital Region' project is the result of a collaboration between the Royal Belgian Institute of Natural Sciences and the Gomphus working group (Naturalistes belges, asbl), and significantly relies on all the observers who contribute to the waarnemingen.be/observations.be database, with financial support from Leefmilieu Brussel/Bruxelles Environnement.

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