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

In vitro 2-deoxy-2-[18F]fluoro-D-glucose uptake: practical considerations

In oncology 2-deoxy-2-[F-18]fluoro-D-glucose ([F-18]-FDG), a glucose analogue, is the most used positron emission tomography (PET) tracer. There are however some limitations due to low metabolic activity or high surrounding physiological uptake in several tumors or regions. Investigating new tracers or methods is expensive and elaborative when animal experiments or phase I clinical trials are used. In vitro experiments can overcome these limitations. We analyzed the influence of incubation time, cell medium conditions, administered activity, and cell density on [F-18]-FDG uptake in six different cell cultures. Glucose transporter 1 (GLUT1)- and hexokinase 2 (HK2)-expression at high and low cell density was analyzed using immunocytochemistry. FDG-uptake increases over time and absence of glucose in the incubation medium increases uptake. By increasing the administered activity, uptake per protein also increases and tracer uptake per protein is lower at higher cell densities. Immunocytochemical analysis reveals a lower expression of both GLUT1 and HK2 at higher cell concentrations. All investigated parameters influenced FDG uptake and therefore we can conclude it is of utmost importance to keep administered activity, incubation medium, and time constant and to correct uptake when cell density changes due to environmental conditions, such as therapy

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