Impact assessment of alien macroinvertebrates in Flanders (Belgium)

Besides habitat fragmentation, the introduction of invasive species is considered to be one of the greatest threats to global biodiversity. Due to increased global trade, habitat degradation and climate change the number of species introductions has increased spectacularly during the last decades. This has led to changes in structure and functioning of ecosystems worldwide. In this study, the impact and spread of alien macroinvertebrates in surface waters in Flanders was investigated. To this end, a large database consisting of biological and physical-chemical data was used, which was collected by the Flemish Environment Agency and supplemented with own sampling campaigns. An integrated approach was aimed for, where the results from laboratory studies, long-term field data analysis and data-driven modelling were combined in order to gain insight in the ecology of alien macroinvertebrate species and the drivers that cause changes in macroinvertebrate community composition. A detailed study on the distribution of alien macroinvertebrates in Flanders revealed that in total, 65 alien macroinvertebrates are established of which 40 are regularly encountered in fresh and slightly brackish inland waters. Most alien taxa belonged to the crustaceans and molluscs originating from North America and the Ponto-Caspian region. Many alien species were first discovered in the east of Flanders from where they started the colonisation of the central and western parts of Flanders. Changes in the macroinvertebrate composition were discovered during the last two decades as a result of changing environmental conditions and the introduction of alien species. When analysing the factors that favoured the establishment and spread of alien macroinvertebrates it was found that shipping, hydro-morphological and physical-chemical factors were detrimental for the success of alien macroinvertebrates. Canals, harbours and the polder waters were hot spots for alien species introductions. Small streams were less invaded by alien macroinvertebrates probably because of a higher biotic resistance and the lack of proper vectors. Case studies of different aquatic ecosystems helped understanding the different factors contributing to successful invasions. The case study on the harbour of Ghent indicated that previously degraded ecosystems are favourable for the early establishment by alien macroinvertebrates. With improving chemical water quality due to the installation of wastewater treatment plants and a stricter environmental legislation not only indigenous, but also alien macroinvertebrates colonised the harbour of Ghent. In the polder waters the indigenous brackish water species decreased in abundance, whereas the American amphipod Gammarus tiginus quickly took in a dominant position after its establishment. These observed changes are probably caused by a decrease in salinity which coincided with an increase of freshwater asselids and the euryhaline species G. tigrinus. It was not only the introduction of the invasive amphipod, but the combination with changing environmental conditions that caused the changes in macroinvertebrate composition. The case study on the Belgian coastal harbours confirmed earlier findings that brackish waters are characterised by a low natural species diversity and a relatively high number of alien species. The harbour of Zeebrugge, which received most international ships, had the highest diversity of alien macroinvertebrates and was also characterised by a high site specific biocontamination index. The knowledge gathered during the case studies was used when making predictions on the future distribution of alien macrocrustaceans in Flanders. Based on data-driven classification and regressions trees it was found that alien macrocrustaceans prefer large rivers and canals with a good chemical water quality and that with increasing conductivity the abundance and species richness of alien macrocrustaceans increases in the brackish water environment. When incorporating the improvements in water quality, it was found that the number of alien species (alien species diversity) will increase in the future, but that the fraction of alien species (alien species abundance) will remain stable. In the last step, an integrated model coupling a habitat suitability model, a water quality model and a migration model was developed to predict the future distribution of a highly invasive alien amphipod species, Dikerogammarus villosus. It was found that D. villosus will invade more large watercourses in Flanders during the next fifteen years as a result of decreases in COD, nitrogen and phosphorous loads and an increase in oxygen concentration. It was calculated that D. villosus spreads with an average speed of five km per year and that given the relatively small size of Flanders, migration speed will not limit its maximal dispersal. The here developed model could be applied as an efficient tool by decision makers to perform risk analysis for (potential) invasive macroinvertebrate species to determine the future distribution range as this could help to reduce the number of species introductions and the impact they have on ecosystem functioning. Besides performing risk assessment several management measures, such as ballast water control, regulations regarding the trade of aquatic alien species and further insight in invaded ecosystems are necessary to reduce the further spread and minimise the impact of invasive alien species

Do my emotions show or not? Problems with transparency estimation in women with borderline personality disorder features

Transparency estimation, that is, estimating the extent to which one’s mental states are observable to others, requires the simultaneous representation of the self and of others’ perspective on the self. Individuals with borderline personality disorder (BPD) have difficulty integrating multiple perspectives when mentalizing, which may be reflected in impaired transparency estimation. A total of 62 participants high and low in BPD features watched emotionally evocative video clips and estimated the transparency of their emotional experience while facial expression coding software (FaceReader) quantified their objective transparency. Individuals high in BPD features showed a larger discrepancy between estimated and objective transparency than individuals low in BPD features, showing that they both over- and underestimated their transparency. Indeed, estimated transparency positively predicted objective transparency in individuals low in BPD features, but not in individuals high in BPD features. Moreover, the ability to estimate intraindividual variability in one’s own objective transparency was moderated by self-reported arousal in the participants high in BPD features. Impairments in transparency estimation were correlated with self-report measures of borderline features, attachment, and mentalizing. In conclusion, we found that borderline features relate to a reduced capacity to estimate the extent to which one’s own emotional states are observable to others. Although replication in clinical samples of BPD patients is needed, the present study provides evidence for problems in mentalizing the (embodied) self from another person’s perspective in BPD

Alien macrocrustaceans in freshwater ecosystems in the eastern part of Flanders (Belgium)

Biological invasions of freshwater macroinvertebrates are gaining more and more interest because the ecological and economical impact of some of these species is high. Since crustacean taxa appear to be successful groups invading new areas, an inventory of the macrocrustaceans in Flanders was made. At least 22 freshwater macrocrustacean species have been reported from Flemish water bodies. A detailed study of six canals, one small artificial watercourse and one natural river in the eastern part of Flanders revealed that invaders such as Dikerogammarus villosus, Gammarus tigrinus and Chelicorophium curvispinum are already quite common. Especially D. villosus is currently rapidly expanding and has a serious impact on native and other exotic gammarid species. Based on observations in neighbouring countries, several additional species are expected to arrive in the near future. A follow-up of the alien species together with a monitoring scheme to detect new incoming species is valuable to estimate the size of the problem and to be able to closely follow their ecological and economical impact

Tackling invasive alien species in Europe: The top 20 issues

Globally, Invasive Alien Species (IAS) are considered to be one of the major threats to native biodiversity, with the World Conservation Union (IUCN) citing their impacts as ‘immense, insidious, and usually irreversible’. It is estimated that 11% of the c. 12,000 alien species in Europe are invasive, causing environmental, economic and social damage; and it is reasonable to expect that the rate of biological invasions into Europe will increase in the coming years. In order to assess the current position regarding IAS in Europe and to determine the issues that were deemed to be most important or critical regarding these damaging species, the international Freshwater Invasives - Networking for Strategy (FINS) conference was convened in Ireland in April 2013. Delegates from throughout Europe and invited speakers from around the world were brought together for the conference. These comprised academics, applied scientists, policy makers, politicians, practitioners and representative stakeholder groups. A horizon scanning and issue prioritization approach was used by in excess of 100 expert delegates in a workshop setting to elucidate the Top 20 IAS issues in Europe. These issues do not focus solely on freshwater habitats and taxa but relate also to marine and terrestrial situations. The Top 20 issues that resulted represent a tool for IAS management and should also be used to support policy makers as they prepare European IAS legislation. © 2014 The Author(s)

Sensory theories of developmental dyslexia: three challenges for research.

Recent years have seen the publication of a range of new theories suggesting that the basis of dyslexia might be sensory dysfunction. In this Opinion article, the evidence for and against several prominent sensory theories of dyslexia is closely scrutinized. Contrary to the causal claims being made, my analysis suggests that many proposed sensory deficits might result from the effects of reduced reading experience on the dyslexic brain. I therefore suggest that longitudinal studies of sensory processing, beginning in infancy, are required to successfully identify the neural basis of developmental dyslexia. Such studies could have a powerful impact on remediation.This is the accepted manuscript. The final version is available from NPG at http://www.nature.com/nrn/journal/v16/n1/abs/nrn3836.html