Effect of water quality on waterbugs (Hemiptera: Gerromorpha & Nepomorpha) in Flanders (Belgium) : results from a large-scale field survey

Macroinvertebrates have been collected in Flanders since 1989 by the Flemish Environment Agency to assess ecological water quality. During the present study, the collected waterbugs were identified to species level. In total, more than 90 000 waterbugs were identified, belonging to 45 species. Two of these are recent additions to Flemish fauna: Sigara iactans was found to be a common species in 1989, the first year of monitoring, which is earlier than the first records reported so far, whereas Cymatia rogenhoferi remains a very rare species. Five different communities could be recognized: (1) species occurring in alkaline waters with a high pH, (2) species occurring in colder waters that can tolerate slightly brackish and nutrient rich water, (3) species from running waters, (4) species from acidic waters and (5) ubiquist species that occurred in all types of water. Owing to the general improvement of chemical water quality during the last decade, most species increased, however, three pollution tolerant species declined significantly: Callicorixa praeusta, Corixa punctata and Sigara striata

Occurrence cubes : a new paradigm for aggregating species occurrence data

In this paper we describe a method of aggregating species occurrence data into what we coined “occurrence cubes”. The aggregated data can be perceived as a cube with three dimensions - taxonomic, temporal and geographic - and takes into account the spatial uncertainty of each occurrence. The aggregation level of each of the three dimensions can be adapted to the scope. Built on Open Science principles, the method is easily automated and reproducible, and can be used for species trend indicators, maps and distribution models. We are using the method to aggregate species occurrence data for Europe per taxon, year and 1km2 European reference grid, to feed indicators and risk mapping/modelling for the Tracking Invasive Alien Species (TrIAS) project

A preliminary field trial to compare control techniques for invasive Berberis aquifolium in Belgian coastal dunes

Non-native Berberis aquifolium is an invasive species in Belgian coastal dunes. With its strong clonal growth through suckers, this evergreen shrub outcompetes native species and affects dune succession. To prevent further secondary spread and mitigate its impact, there was an urgent need for knowledge on the effectiveness of control measures, both at the plant and habitat level. Here, we report on a first control experiment. Individual B. aquifolium clones were subjected to one of four treatments (manual uprooting, foliar herbicide application, stem cutting followed by herbicide or salt application), with regrowth being measured up to one year after treatment. We analyzed the relationship between kill rate, treatment, dune area, plant volume and number of plant stems using a generalized linear model. Berberis aquifolium plants proved most susceptible to foliar herbicide application (5% glyphosate solution), resulting in 88% (64%-97%) of the clones dying after treatment. The predicted kill rate decreased with an increasing number of stems under all treatments. We discuss the limitations of our experiment and the potential for actual field application of the different treatments. We present some guidelines for future control that may become further refined as experience builds up and we provide some recommendations for tackling invasive alien species in Atlantic dune ecosystems

Increasing understanding of alien species through citizen science (Alien-CSI)

There is no sign of saturation in accumulation of alien species (AS) introductions worldwide, additionally the rate of spread for some species has also been shown to be increasing. However, the challenges of gathering information on AS are recognized. Recent developments in citizen science (CS) provide an opportunity to improve data flow and knowledge on AS while ensuring effective and high quality societal engagement with the issue of IAS (Invasive Alien Species). Advances in technology, particularly on-line recording and smartphone apps, along with the development of social media, have revolutionized CS and increased connectivity while new and innovative analysis techniques are emerging to ensure appropriate management, visualization, interpretation and use and sharing of the data. In early July 2018 we launched a European CO-operation in Science and Technology (COST) Action to address multidisciplinary research questions in relation to developing and implementing CS, advancing scientific understanding of AS dynamics while informing decision-making specifically implementation of technical requirements of relevant legislation such as the EU Regulation 1143/2014 on IAS. It will also support the EU biodiversity goals and embedding science within society. The Action will explore and document approaches to establishing a European-wide CS AS network. It will embrace relevant innovations for data gathering and reporting to support the implementation of monitoring and surveillance measures, while ensuring benefits for society and citizens, through an AS CS European network. The Action will, therefore, increase levels of participation and quality of engagement with current CS initiatives, ensuring and evaluating educational value, and improve the value outcomes for potential users including citizens, scientists, alien species managers, policy-makers, local authorities, industry and other stakeholders

Alien macroinvertebrates in Flanders (Belgium)

Biological invasions of aquatic macroinvertebrates are gaining interest because of their potential for significant ecological and socio-economic impacts (positive and negative). In the present study, an inventory was made of the alien macroinvertebrates occurring in Flanders (northern Belgium) based on extensive existing collections of biological samples and supplemented with our additional sampling programs. Fresh and brackish waters as well as the Belgian coastal harbours, situated at the interface of the marine environment, were investigated. Over 2,500 samples containing alien macroinvertebrates were identified to species level, which allowed us to accurately map their distribution in Flanders. Alien macroinvertebrates are widespread and abundant in many watercourses in Flanders. Four new macroinvertebrate species for Flanders were discovered: Procambarus clarkii (Girard, 1852), Echinogammarus trichiatus (Martynov, 1932), Synurella ambulans (F. Müller, 1846) and Laonome calida Capa, 2007. Fifty-two alien macroinvertebrates were encountered in fresh and slightly brackish surface waters, and 21 alien species were reported for the Belgian part of the North Sea and its adjacent estuaries. Most alien macroinvertebrates collected were crustaceans and molluscs. Alien species found in fresh and brackish water mainly originate from the Ponto-Caspian area and North America; fewer species originated from Asia and South- and East-Europe. The major pathways were probably shipping and dispersal through canals. Based on observations in neighbouring countries, several additional species are expected to arrive in the near future. Follow-up work is needed to assess the ecological and economic impacts of existing alien macroinvertebrates, and a monitoring program is needed to detect new incoming species

Reproduction of Crassula helmsii by seed in western Europe

The amphibious plant species Crassula helmsii is a widely established and still-spreading alien in various parts of Europe, where it is considered invasive as its dense swards stress the viability of local biota. The species was considered to exclusively reproduce through vegetative means, until ex situ germination was recorded from a single locality in Belgium. We assessed whether this seed viability holds on a wider scale, by testing 16 populations from The Netherlands, Belgium, northern France, eastern England and northern Germany in a greenhouse germination experiment. Seedlings were observed from all populations but two, and from each of the five countries. Although most fruits were lacking seeds and the inferred germination percentages were overall low, germinable seed numbers are considerable given the high density of flowering stems. An in situ test revealed seeds to make it through normal winter conditions without signs of physical damage and with retention of germinability. Our results suggest that reproduction by seed is a relatively cryptic but widespread phenomenon throughout western Europe. The persistency of seed banks requires further investigation. Nonetheless, these findings already challenge the efficacy of techniques currently applied in C. helmsii control