The trophic function of Dikerogammarus villosus (Sowinsky, 1894) in invaded rivers: a case study in the Elbe and Rhine

Abstract

Taking into account the continuous increase in freshwater introductions, and to support the recent European legislation on invasive alien species, the identification of priority pathways and gateways of introductions is of utmost importance to develop adequate control strategies. The aim of this paper was to analyse the main pathways and gateways of introductions of freshwater alien species in Europe. Based on a thorough review of the scientific and grey literature, information on pathways, country and year of initial introduction of all freshwater alien species in Europe, was retrieved. The spatial and temporal patterns and trends of biological invasions in freshwater ecosystems in Europe, in relation to different pathways, were assessed. Our results pinpoint the major importance of aquaculture, pet/aquarium trade and stocking activities as pathways of introduction of freshwater alien species in Europe. For species native to some European countries, shipping and inland canals were the most important pathways, highly responsible for the entry of many harmful species. Germany, the United Kingdom and Italy were the main entry gateways of freshwater alien species in Europe. We found a geographical pattern related to some pathways of introduction in Europe: introductions through inland canals were concentrated in Central/North-eastern Europe, while introductions through pet/terrarium/aquarium trade were mainly observed in Central/Western Europe. While Chordata species entered Europe mainly through the three major above mentioned pathways, many harmful Arthropoda and Mollusca entered through shipping and inland canals. The information gathered in this study clearly indicates the entry routes that should be prioritised by Member States, for which stronger control and management actions should be implemented and prevention efforts concentrated under the scope of the related new EU Regulation.

Fish but Not Macroinvertebrates Promote Trophic Cascading Effects in High Density Submersed Plant Experimental Lake Food Webs in Two Contrasting Climate Regions

“…Besides, in temperate systems, the lack of effects promoted by G. lacustris can also be explained by differences between experimental designs, as we used bottomless mesocosms, allowing the presence of alternative food resources. As an opportunistic feeder, G. lacustris tend to use the most easily available food resources [76][77][78], which was probably not the case for zooplankton in our design where other food items could become available.…”

Is Dikerogammarus villosus (Crustacea, Gammaridae) a ‘killer shrimp’ in the River Rhine system?

“…periphyton, leaves, macrophytes), dependence of the mean carbon signature of D. villosus and periphyton was tested using a linear regression model (lm) for all microhabitats from which samples of the periphyton could be obtained. We also checked for individual differences in the reliance on periphyton within microhabitats taking into account the trophic enrichment factor (TEF; for change in isotopic signature between diet and consumer) for carbon isotopes in tissue of D. villosus (plant diet: 3.56%), determined by Hellmann et al (2015).…”

Predator diet, origin or both? Factors determining responses of omnivorous amphipods to predation cues

“…On the other hand, some field studies demonstrated its low trophic position, with a large share of plant food in its diet (Hellmann et al, 2015;Koester et al, 2016). Thus, the feeding habits of D. villosus clearly depend on a number of factors, such as the community structure (Hellmann et al, 2015) or temperature (van der Velde et al, 2009). Notwithstanding these discrepancies, it can perceive the presence of a fish not only as a danger, but also as information about potential food resources (Paterson et al, 2013), especially if the fish consumed chironomids-an important part of the diet of invasive amphipods (Bacela-Spychalska & van der Velde, 2013).…”

“…This species is often regarded as an omnivore with a strong tendency to predation on macroinvertebrates (Dick & Platvoet, 2000;Dick et al, 2002;MacNeil & Platvoet, 2005). On the other hand, some field studies demonstrated its low trophic position, with a large share of plant food in its diet (Hellmann et al, 2015;Koester et al, 2016). Thus, the feeding habits of D. villosus clearly depend on a number of factors, such as the community structure (Hellmann et al, 2015) or temperature (van der Velde et al, 2009).…”