In recent years, policy-makers have sought the development of appropriate tools to prevent and manage introductions of invasive species. However, these tools are not well suited for introductions of non-target species that are unknowingly released alongside intentionally-introduced species. The most compelling example of such invasion is arguably the topmouth gudgeon Pseudorasbora parva, a small cyprinid species originating from East Asia. A combination of sociological, economical and biological factors has fuelled their rapid invasion since the 1960s; 32 countries (from Central Asia to North Africa) have been invaded in less than 50 years. Based on a combination of monitoring surveys (2535 populations sampled) and literature reviews, this paper aims to quantify and characterise important invasion parameters, such as pathways of introduction, time between introduction and detection, lag phase and plasticity of life history traits. Every decade, five new countries have reported

Aim To analyse the patterns in species richness and endemism of the native European riverine fish fauna, in the light of the Messinian salinity crisis and the Last Glacial Maximum (LGM). Location European continent.Methods After gathering native fish faunistic lists of 406 hydrographical networks, we defined large biogeographical regions with homogenous fish fauna, based on a hierarchical cluster analysis. Then we analysed and compared the patterns in species richness and endemism among these regions, as well as species-area relationships.

Aim To analyse the patterns in species richness and endemism of the native European riverine fish fauna, in the light of the Messinian salinity crisis and the Last Glacial Maximum (LGM). Location European continent.Methods After gathering native fish faunistic lists of 406 hydrographical networks, we defined large biogeographical regions with homogenous fish fauna, based on a hierarchical cluster analysis. Then we analysed and compared the patterns in species richness and endemism among these regions, as well as species-area relationships.

Summary Interactions between adult individuals of the introduced Eastern mosquitofish Gambusia holbrooki and two native fish species to the Iberian Peninsula, the Iberian toothcarp Aphanius iberus and the Valencia toothcarp Valencia hispanica, were studied in mesocosm and laboratory experiments. Eastern mosquitofish always excluded both Valencia and Iberian toothcarp when the ratio introduced‐to‐native was at unity or favourable to the non‐native species. Food availability did not decrease significantly in the mesocosm experimental units. However, specimens of native species had a greater number of empty guts than those of Eastern mosquitofish at the end of the mesocosm experiment. Ethograms were constructed based on qualitative observations in aquaria, with a special emphasis on social behaviours, in particular agonistic (which ultimately were not observed between the species). Satiety (maximum prey number) and voracity (number of prey consumed per unit of time) of the three species were measured in aquaria. The Eastern mosquitofish achieved the highest foraging values (maximum prey = 11, at 11–12 prey min−1), whereas Valencia toothcarp achieved the lowest values (maximum prey = 7, at 5–6 prey min−1). The observed interactions between Eastern mosquitofish and the two native species are discussed.

Mediterranean river systems are characterised by more diverse fish assemblages and regional ecological processes compared with the rest of Europe. A data set from Mediterranean France, Iberia and Greece ( 2000 sites) was used to describe the characteristics of fish assemblages, explore their responses to anthropogenic disturbance and analyse the implications for river quality assessment. There was a southwards decline in species richness per site, but endemicity and proportion of alien species increased. Sites in the eastern Mediterranean had higher endemicity, lower site richness and lower number of alien species than sites in western Mediterranean Europe. Assemblage composition differed between Mediterranean sub-regions, but was dominated by three major fish types: a salmonid fish type common throughout the study area and two cyprinid-dominated fish types (in some sub-regions, Salmo trutta L. is present but not numerically dominant), corresponding to a gradient in hydrological and temperature regimes. Metric responses to perturbation were compared with those found at the European (larger scale) and basin (smaller scale) levels. Overall metric response was weaker in this Mediterranean application. The best responses to human pressure were usually obtained with abundance-based metrics and included the contribution of naturalised alien species. Some widespread alien species contributed to the response to anthropogenic alteration (notably Cyprinus carpio L. and Lepomis gibbosus (L.)). K E Y W O R D S :alien species, fish metrics, fish types, guilds, human impacts, Mediterranean streams.

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