Distribution and ecology of the stoneflies (Plecoptera) of Flanders (Belgium)

Based on a literature survey and the identification of all available collection material from Flanders, a checklist is presented, distribution maps are plotted and the relationship between the occurrence of the different species and water characteristics is analysed. Of the sixteen stonefly species that have been recorded, three are now extinct in Flanders (Isogenus nubecida, Taeniopteryx nebulosa and T. schoenemundi), while the remaining species are rare. The occurence of stoneflies is almost restricted to small brooks, while observations in larger watercourses are almost lacking. Although a few records may indicate that some larger watercourses have recently been recolonised, these observations consisted of single specimens and might be due to drift. Most stonefly population are strongly isolated and therefore extremely vulnerable. Small brooks in the Campine region (northeast Flanders), which are characterised by a lower pH and a lower conductivity, contained a different stonefly community than the small brooks in the rest of Flanders. Leuctra pseudosignifera, Nemoura marginata and Protonemura intricata are mainly found in small brooks in the loamy region, Amphinemura staandfussi, Isoperla grammatica, Leuctra fusca, L.hippopus, N. avicularis and P. meyeri mainly occur in small Campine brooks, while L. nigra, N. cinerea and Nemurella pictetii can be found in both types. Nemoura dubitans can typically be found in stagnant water fed with freatic water. Sustainable populations of these stonefly species can only be achieved when their present habitats are adequately protected and in addition, measures should be taken to connect and enlarge the remaining populations

Application of decision trees to analyze the ecological impact of invasive species in Polder lakes in Belgium

Polder lakes in Belgium are stagnant waters that were flooded by the sea in the past. Over the years, the salinity of these systems decreased. Several of these systems are colonized by invasive species (often related to fish stocking). The aim of this study was to analyze the ecological impact of invasive macroinvertebrates on native species and to assess to what extend physical-chemical variables affected the presence of invasive species. For this, decision trees were constructed, relating the abiotic lake characteristics to the presence of macroinvertebrates (both invasive and non-invasive). The major advantages of the use of single-target decision trees are the transparency of the rule sets and the possibility to use relatively small databases, since these specific systems were hardly monitored until present

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

Alien macro-crustaceans in freshwater ecosystems in Flanders

During the last decades, the spread of aquatic alien species has increased enormously. Range extensions of exotic species have been facilitated by the interconnection of river basins and increased shipping. Invasive species are considered as an important component in the decline of diversity of communities and the abundance of other species in freshwater ecosystems. Besides their ecological impact, alien species are considered to cause worldwide economical damage. Currently, eighteen alien macro-crustaceans have been found in freshwater ecosystems in Flanders. One of these invasive species is the Ponto-Caspian invader Dikerogammarus villosus, which has invaded most of Europe since the beginning of the 1990s, mainly as result of the opening of the Main-Danube canal. This species was recorded for the first time in the east of Flanders in 1997. In order to assess the potential effect of this species on other macroinvertebrates, laboratory experiments as well as field observations were conducted. All types of prey that were used in predator-prey experiments were consumed by D. villosus, especially species that were less mobile such as Chironomidae. Substrate preference experiments indicated that D. villosus preferred a stony substrate. Using decisions trees to model field observations, it could be concluded that D. villosus could mainly be found in habitats with an artificial bank structure, a high oxygen concentration and a low conductivity, which corresponds with the canals where it has been observed mostly in Flanders

Effects of metal contamination on the activity and diversity of carabid beetles in an ancient Pb-Zn mining area at Plombières (Belgium)

Carabid beetles were monthly sampled with pitfall traps in the ancient Pb-Zn mining area of Plombieres during one year. Based on the total soil concentrations of lead, zinc, cadmium and copper, it was expected that zinc would probably have the most adverse effects on the populations. Activity and species richness of carabid beetles were, however, not significantly correlated with total zinc concentration nor with the water soluble and the calciumchloride extractable concentration. In fact, despite the high soil concentrations, carabid beetles did not seem to be affected in the study area. The apparent lack of effects at the high observed zinc concentrations is probably caused by the low bioavailability of zinc to the beetles in the litter of the study sites which was also reflected in the low observed water soluble zinc concentrations

First occurrence of the Ponto-Caspian amphipod Echinogammarus trichiatus (Martynov, 1932) (Crustacea: Gammaridae) in Belgium

The Ponto-Caspian amphipod species Echinogammarus trichiatus (Martynov, 1932) was found in Belgium for the first time in June 2009 at two different locations in an artificial lake bordered by two large canals. Adults as well as juveniles were found in small numbers and occurred together with several other Ponto-Caspian species such as Dikerogammarus villosus (Sowinsky, 1894) and Dreissena polymorpha (Pallas, 1771). An identification key to the genus Echinogammarus of inland waters in Western Europe is provided. This first record of yet another new amphipod invader in Belgium demonstrates the continuous introduction of alien species into West European waters

Drivers of benthic macroinvertebrate assemblages in equatorial alpine rivers of the Rwenzoris (Uganda)

The Sub-Saharan alpine freshwater biodiversity is currently impacted by human settlements, climate change, agriculture, and mining activities. Because of the limited biodiversity studies in the region, a better understanding is needed of the important environmental variables affecting macroinvertebrate assemblages. In this paper, macroinvertebrate diversity responses to 18 environmental variables were studied at 30 sites along unique Rwenzori rivers at the equator in Uganda. We hypothesized that anthropogenic disturbance and local environmental variables affect macroinvertebrate diversity, irrespective of altitudinal gradients. Based on altitude and climate, the sites were subdivided into three altitude groups consisting of 10 sites each: upstream (US) 1400–1600 m.a.s.l.; midstream (MS) 1091–1399 m.a.s.l., and downstream (DS) 900–1090 m.a.s.l. A total of 44 macroinvertebrate families and 1623 individuals were identified. The macroinvertebrate diversity patterns were influenced by temperature, altitude, and latitude. Regression analysis revealed that temperature and nickel, were negative predictors of taxa richness. Nickel, which is released by mining activity, is detrimental to aquatic communities in Sub-Saharan alpine ecosystems. Significant longitudinal variation in macroinvertebrate diversity was observed between the sites, which were also affected by mineral and temperature gradients. Our study highlights the need for long-term monitoring in this region to detect and reduce the threats to river biodiversity from anthropogenic activity

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

Development and assessment of an integrated ecological modelling framework to assess the effect of investments in wastewater treatment on water quality

xxxxxWorldwide, large investments in wastewater treatment are made to improve water quality. However, the impacts of these investments on river water quality are often not quantified. To assess water quality, the European Water Framework Directive (WFD) requires an integrated approach. The aim of this study was to develop an integrated ecological modelling framework for the River Drava (Croatia) that includes physical-chemical and hydromorphological characteristics as well as the ecological river water quality status. The developed submodels and the integrated model showed accurate predictions when comparing the modelled results to the observations. Dissolved oxygen and nitrogen concentrations (ammonium and organic nitrogen) were the most important variables in determining the ecological water quality (EWQ). The result of three potential investment scenarios of the wastewater treatment infrastructure in the city of Varaždin on the EWQ of the River Drava was assessed. From this scenario-based analysis, it was concluded that upgrading the existing wastewater treatment plant with nitrogen and phosphorus removal will be insufficient to reach a good EWQ. Therefore, other point and diffuse pollution sources in the area should also be monitored and remediated to meet the European WFD standar