Search

The spread rates of alien species of Amphipoda and Mysida were calculated for the Dnieper, Pripyat and Neman rivers in the territory of Belarus. The maximal values of spread rate were obtained for Dikerogammarus villosus (in the Pripyat River - 37.8 km/year, in the Dnieper River - 17 km/year) and Dikerogammarus haemobaphes (in the Pripyat River - 53.6 km/year, in the Dnieper River - 17 km/year), while the minimal values of spread rate were calculated for mysids Paramysis lacustris (in the Dnieper River - 0.4 km/year) and Limnomysis benedeni (in the Dnieper River - 0.6 km/year), also for amphipods Chelicorophium robustum (in the Dnieper River - 0.5 km/year) and Echinogammarus trichiatus (in the Dnieper River - 1.3 km/year). The differences in the spread rates of species connected with the time of their first records at the monitoring points and the intensity of economic activities in the studied rivers.

The regions of the Black, Caspian, and Azov seas are known for being both (i) the place of extensive crustacean radiation dated to the times of Paratethys and Sarmatian basins, and (ii) present donors of alien and invasive taxa to many areas worldwide. One amphipod morphospecies,Dikerogammarus haemobaphes, is known both as native to rivers draining to the Black and Caspian seas as well as a successful invader (nicknamed demon shrimp) in Central and Western European rivers. Based on mitochondrial (COI and 16S) and nuclear (28S) datasets and 41 sampling sites, representing both the native (19) and the invaded (22) range, we assessed cryptic diversity, phylogeography and population genetics of this taxon. First, we revealed the presence of two divergent lineages supported by all markers and all species delimitation methods. The divergence between the lineages was high (18.3% Kimura 2-parameter distance for COI) and old (ca. 5.1 Ma), suggesting the presence of two cryptic species withinD. haemobaphes. Lineage A was found only in a few localities in the native range, while lineage B was widespread both in the native and in the invaded range. Although genetic divergence within lineage B was shallow, geographic distribution of 16S and COI haplotypes was highly heterogeneous, leading us to the definition of four Geo-Demographic Units (GDUs). Two GDUs were restricted to the native range: GDU-B1 was endemic for the Durugöl (aka Duruşu) Liman in Turkey, whereas GDU-B2 occurred only in the Dniester River. GDU-B3 was both present in several localities in the native range in the Black Sea drainage area and widespread in Central and Western Europe. The GDU-B4 was found exclusively in the Moskva River in Russia. Extended Bayesian Skyline Plot indicated steady growth of GDU-B3 population size since 30 ka, pointing to the rather old history of its expansion, first in the late Pleistocene in the native range and nowadays in Central and Western Europe. The analysis of haplotype distribution across the present distribution range clearly showed two invasion routes to Central and Western Europe. The first one, originating from the lower Dnieper, allowed the demon shrimp to colonize Polish rivers and the Mittellandkanal in Germany. The second one, originating from the Danube delta, allowed to colonize the water bodies in the upper Danube basin. The UK population has originated from the Central Corridor, as only a haplotype found exclusively along this route was recorded in the UK. Population genetics analysis showed that the invasion of the demon shrimp along the Central Corridor was not associated with the loss of genetic diversity, which might contribute to the success of this invader in the newly colonized areas.

We report a considerable range expansion of four Ponto-Caspian amphipod species in transitional waters along the southeastern Baltic Sea coast. Chaetogammarus warpachowskyi and Dikerogammarus haemobaphes were found for the first time in Latvia, the former being common along the coast, while the latter was encountered only in the port of Riga. This indicates a 400 to 600 km expansion along the coast, assuming an origin from the Curonian or Vistula lagoons. We also officially document an expansion for Chelicorophium curvispinum in Latvia of ca. 300 km until Riga, confirming recent unpublished records. Moreover, we document a second invasion route of Pontogammarus robustoides into Estonia from nearby Latvian waters by uncovering a population at the port of Parnu. This species was previously known in Estonia only from the Gulf of Finland (>500 km from Parnu). With the exception of D. haemobaphes, all newly recorded species were represented by various life-stages and ovigerous females, indicating viable populations. Overall, our findings reveal that Ponto-Caspian amphipods are much more widespread in the Baltic area than previously known and highlight the need for more stringent monitoring.

The amphipod Dikerogammarus haemobaphes is a high-risk carrier of parasites that impact wildlife in its non-native range. Studies using the mitochondrial genes, Cytochrome Oxidase Sub-Unit 1 (cox1) and small-subunit ribosomal RNA gene (16S), provide some nucleotide detail for understanding the evolution and phylogeography of this species. Despite this, the origins of the invasion remain unknown, as do the origins of its parasites. This study provides the full annotated mitochondrial genome (15,460 bp) of D. haemobaphes, consisting of 2 rRNAs, 24 tRNAs and 14 protein coding genes. Mitochondrial genes from the UK isolate are compared to existing data on NCBI and are used in a concatenated phylogenetic approach and identify D. haemobaphes as an early member of the Gammaridae (Amphipoda). Viral, bacterial, protistan and microsporidian parasites are present across the Gammaridae, including D. haemobaphes, suggesting the ancestor of the Gammaridae harboured related diseases, and that further screening of amphipods is likely to reveal further microparasite diversity. This correlation suggests that other gammarid invaders have the potential to harbour a range of microparasites. The mitochondrial genome of this species will act a resource to facilitate our understanding of geneflow, disease epidemiology and evolutionary history in this invasion-disease model.

Biological invasions could have major implications for the management and conservation of freshwater systems if they lead to a misclassification of waterbodies. However, there is limited understanding of the sensitivity of existing biomonitoring tools to invasive species in rivers; and even less known regarding how they influence community taxonomic and functional measures. This research explores the response of freshwater macroinvertebrate communities to biological invasion using taxonomic and functional indices. Utilising a long-term dataset (spanning 2000–2019, 5,988 samples) from rivers in England, the performance of four biomonitoring tools (WHPT, WHPT-ASPT, LIFE and PSI) and two community functional indices (functional richness and redundancy) was examined before and after the colonisation of the invasive species, Dikerogammarus haemobaphes (Eichwald, 1841; Crustacea: Gammaridae). This species represents a recent (first record 2012) and highly successful invader, allowing its range expansion within waterbodies to be examined in detail. Spatial (national and basin level) and seasonal (spring and autumn) effects were investigated using a before–after control–impact (BACI) experimental framework and linear mixed effects models. Results indicated that invasion by D. haemobaphes resulted in significant reductions to the WHPT index and functional diversity metrics (richness and redundancy) while more subtle patterns were observed for other metrics. Analysis of seasonal and individual river basins (River Trent and R. Thames) identified largely consistent responses. The establishment of D. haemobaphes also resulted in some modifications to the functional composition of aquatic communities primarily associated with voltinism and resistance features. Synthesis and applications. Our findings indicate that Dikerogammarus haemobaphes should be considered a significant pressure to riverine communities. These results have implications for biomonitoring, which informs managerial actions as effects may not be detected using a single taxonomic index. Community functional measures are useful in characterising the effects of invasive species and may form a valuable part of the ‘toolbox’ used for studying biological invasions in rivers. The research illustrates the need to consider the wider threats posed by invasive species on the long-term integrity of freshwaters and the efficacy of freshwater biomonitoring tools.

Two Ponto-Caspian amphipods, Dikerogammarus villosus and Dikerogammarus haemobaphes, have expanded their geographical ranges from eastern Europe into Great Britain in recent years. This study represents one of the first examining the distribution and habitat preferences of coexisting populations of D. haemobaphes and D. villosus via field and laboratory experiments in the UK. Field surveys of a recently invaded lowland reservoir in the UK are complimented with ex situ laboratory mesocosm experiments examining the substrate preferences of coexisting populations of D. villosus and D. haemobaphes. Results from the field study indicated that D. haemobaphes dominated the macroinvertebrate community within the reservoir and demonstrated a strong affinity for large cobble and artificial substrates. D. villosus occurred at lower abundances but displayed a strong preference for coarse cobble substrates. A third invasive amphipod, Crangonyx pseudogracilis, was largely confined to sand/silt habitats. Laboratory mesocosm experiments clearly supported the field observations of D. villosus and D. haemobaphes with both species demonstrating a preference for cobble substrates. Results from the study highlight the importance of characterising physical habitat when investigating biological invasions and suggest that habitat availability may influence the extent and speed at which range expansion of new amphipod invaders occurs.

The native area of gammarids from the so-called ‘Caspian complex’, Pontogammarus robustoides (G.O. Sars, 1894), Obesogammarus crassus (G.O. Sars, 1894), Dikerogammarus haemobaphes (Eichwald, 1841) ...

The year-to-year and seasonal dynamics of the diversity and distribution of alien species in benthic communities of the Saratov Reservoir is given on the basis of the results of studies in 2009–2012. The dependence of alien species distribution on environmental factors, such as oxygen content, ion composition, temperature, and pH, is presented. It is shown that the highest invasive activity among alien species is inherent in mussels Dreissena rostriformis bugensis, polychaetes Hypania invalida, and amphipods Dikerogammarus haemobaphes and Chaetogammarus warpachowskyi in the deep water of the reservoir and gastropods Lithoglyphus naticoides in the near-shore area.

Ponto-Caspian gammarids have invaded European waters, affecting local communities by predation and competition. Their ranges and dispersal rates vary across Europe, which may result from their interspecific interactions, accelerating or reducing migrations. We checked this hypothesis by testing interference competition among co-occurring invaders: Dikerogammarus villosus, D. haemobaphes and Pontogammarus robustoides. We used 140-cm long tanks (gravel substratum), divided into seven compartments. We introduced 25 “residents” into the outermost compartment, separated with a barrier. After 1 h, we introduced 25 “intruders”. After the next 1 h, we removed the barrier and the gammarids dispersed in the tank. After 4 or 20 h, we counted the gammarids in the compartments. We tested all pairwise species combinations and single-species controls. Dikerogammarus villosus displaced other species (P. robustoides only after 4 h) and reduced its own motility after 20 h in their presence. Pontogammarus robustoides stimulated the short-time migrations of D. villosus intruders and of D. haemobaphes. As P. robustoides migrated spontaneously much more than Dikerogammarus spp., its impact decreased after longer time. Dikerogammarus haemobaphes stimulated the short-time movement of P. robustoides intruders but reduced the long-time relocation of this species. In general, gammarid dispersal increased in the presence of stronger competitors (D. villosus and P. robustoides, especially residents) and decreased in response to weaker competitors (D. haemobaphes). Thus, competitive interactions may affect dispersal of invasive gammarids and contribute to the fastest spread of the weakest competitor, D. haemobaphes observed in the field, whereas the strongest species, D. villosus was the latest newcomer in many novel areas.

The impact of invasive gammaridean species on native biodiversity is well documented, but the potential for them to disrupt ecosystem functioning is less well understood. Native freshwater amphipods are considered to be archetypal leaf shredders and are considered key to leaf litter processing within rivers. It is possible that invasions may interfere with key ecosystem processes such as leaf litter breakdown, due to behavioural traits displayed by the invasive species. In two laboratory experiments, we compared the leaf shredding efficiency of the native Gammarus pulex and Dikerogammarus haemobaphes, a recently established Ponto–Caspian invader in the UK. We hypothesised that in isolation G. pulex would have a greater shredding efficiency than D. haemobaphes and that, in the presence of the invasive, leaf shredding and survival of G. pulex would be reduced. The results supported our hypothesis that, in isolated conditions, G. pulex consumed significantly more leaves than D. haemobaphes. Under mixed treatments, G. pulex leaf consumption and survival, although not statistically significant, appeared to be reduced. The implications of our findings suggest that the potential displacement of G. pulex from its native range, by D. haemobaphes, could lead to a decline in leaf litter processing and recycling in rivers within the UK.

Dikerogammarus haemobaphes, the 'demon shrimp', is an amphipod native to the Ponto-Caspian region. This species invaded the UK in 2012 and has become widely established. Dikerogammarus haemobaphes has the potential to introduce non-native pathogens into the UK, creating a potential threat to native fauna. This study describes a novel species of microsporidian parasite infecting 72.8% of invasive D. haemobaphes located in the River Trent, UK. The microsporidium infection was systemic throughout the host; mainly targeting the sarcolemma of muscle tissues. Electron microscopy revealed this parasite to be diplokaryotic and have 7-9 turns of the polar filament. The microsporidium is placed into the 'Cucumispora' genus based on host histopathology, fine detail parasite ultrastructure, a highly similar life-cycle and SSU rDNA sequence phylogeny. Using this data this novel microsporidian species is named Cucumispora ornata, where 'ornata' refers to the external beading present on the mature spore stage of this organism. Alongside a taxonomic discussion, the presence of a novel Cucumispora sp. in the United Kingdom is discussed and related to the potential control of invasive Dikerogammarus spp. in the UK and the health of native species which may come into contact with this parasite.

Amphipods are very successful invaders in European inland waters including lakes. There are several vectors identified as responsible for amphipod species introductions and spread, with overland transport increasingly recognized as particularly important, especially in conjunction with transport between sites of sailing and/or angling activity. In this study two species of invasive gammarids with a wide distribution range in Europe, Dikerogammarus haemobaphes and Pontogammarus robustoides, were tested for their ability to attach and remain adhered to sailing rope. The results of the experiment show that both species may have high potential to be transported with sailing/angling equipment, as the percentage of individuals remaining attached to the rope after 30 s of ‘holding’ followed by 30 s of ‘shaking’ was very high (24% and 17%, for D. haemobaphes and P. robustoides, respectively). The necessity for preventative measures to stop translocation of these species between European water bodies is emphasized and discussed. Copyright © 2015 John Wiley & Sons, Ltd.

The spread of alien crustaceans has significantly contributed to the homogenization of macroinvertebrate fauna of European freshwaters. However, little is known about alien Peracarida crustaceans of the Sava River, which represents the most important corridor for the spread of invasive species into Dinaric rivers with highly endemic fauna. In this study, we investigated Peracarida (Amphipoda, Isopoda and Mysida) collected during three years (2011, 2012 and 2015) from a total of 61 sites along the entire course of the Sava River. Besides describing the longitudinal pattern of Peracarida assemblages, we tested the hypothesis that bank reinforcement structures facilitate peracarid invasions by comparing densities and assemblages on natural and artificial substrate at 15 sites. In a total, 14 peracarid crustacean species (5 native and 9 alien) were recorded. The Upper third of Sava was inhabited by native peracarids only, while the Middle and Lower Sava were dominated by alien species. The invasive amphipods Dikerogammarus haemobaphes, Chelicorophium sowinskyi and Chelicorophium curvispinum, and invasive isopod, Jaera istri, were the most abundant species along the middle course. Densities of alien peracarids in the Middle Sava were the highest and their share in macroinvertebrate assemblages was very variable, while the Lower Sava had the highest number of alien species in low densities. The densities of alien amphipods and isopods were in most cases significantly higher on bank reinforcement structures than on natural substrate. Therefore, artificial stony substrates act as stepping stones of invasion for alien peracarids and largely contribute to their success in large lowland rivers.

Increasing colonization of non-native amphipod species in the River Thames, United Kingdom, has altered aquatic ecology and called existing management practices into question. We studied the distribution patterns of recent non-native (Dikerogammarus haemobaphes (Eichwald, 1841)), established non-native (Crangonyx pseudogracilis (Bousfield, 1958)), and native amphipod (Gammarus pulex (Linnaeus, 1758)) species, as well as habitat and human influences across 84 sites in the upper Thames catchment. Our findings showed widespread distribution and density of G. pulex relative to D. haemobaphes, suggesting that the full impact of the current spread has yet to be felt since its 2012 introduction. Different habitat utilization patterns are explained through habitat partitioning: both D. haemobaphes and C. pseudogracilis occupied vegetative habitats, not pebble/gravel habitats where the native G. pulex was most often found. The association between D. haemobaphes and boating presence implies that effective biosecurity would be best focused on boat traffic in the Thames and Cherwell rivers.

Summary 1. Biological invasions are regarded as one of the greatest threats to biological diversity. One of the macroinvertebrate groups with the largest number of invasive species in fresh water are gammarid amphipods. Their omnivorous (including predatory) feeding behaviour may facilitate their spread and establishment in new areas. 2. Dikerogammarus villosus, the ‘killer shrimp’, is a well-known example of a Ponto-Caspian gammarid that is a very effective predator and successful coloniser in Europe. There are, however, other invasive Ponto-Caspian amphipods, which have spread successfully in Northern, Central and Western Europe. Our aim here was to test whether two of such invaders (Pontogammarus robustoides and Dikerogammarus haemobaphes) are also more predacious than a native species (Gammarus fossarum). 3. Stable isotope analysis (δ15N and δ13C) of Ponto-Caspian amphipods coexisting in a reservoir demonstrated that the trophic positions of P. robustoides and D. haemobaphes were similar to that of D. villosus. Echinogammarus ischnus and Chelicorophium curvispinum occupied the lowest position in the food web, while the native Gammarus fossarum (collected from another waterbody) had an intermediate trophic position. 4. Stomach content analysis of P. robustoides, D. haemobaphes and G. fossarum collected in the field, as well as laboratory feeding experiments, was used to compare diet and feeding preferences among the two invasive and one native species. All three species were omnivorous and predacious. However, the two invasive species (P. robustoides and D. haemobaphes) were more effective predators than G. fossarum and showed a clear preference for animal prey and tissue. 5. Pontogammarus robustoides and D. haemobaphes may, like D. villosus, also be called ‘killer shrimps’ and could have a similar impact as invaders of European freshwater and brackish waterbodies.

Organisms inhabiting shallow near-shore waters are at risk of desiccation during water level fluctuations. Using laboratory experiments, we investigated the survival and behavioural defences of four freshwater amphipod species during substratum drying: three Ponto-Caspian invaders (Pontogammarus robustoides, Dikerogammarus haemobaphes and Dikerogammarus villosus) and the native Gammarus fossarum. We hypothesized that they would be able to survive air exposure events as well as to adjust their behaviour by following the decreasing water level and/or burying in the sediments. To test these hypotheses, we examined survival of each species on gradually drying sandy substratum as well as their horizontal and vertical migration behaviours. P. robustoides was most resistant to substratum drying and was the only species burying into the substratum. On the other hand, G. fossarum exhibited distinct horizontal migrations following the retreating waterline. These two species seem to be particularly well adapted to the drying environment. Defence mechanisms of D. haemobaphes and D. villosus were less efficient, though the former species also followed the retreating waterline to some extent. Our study demonstrates that exotic and native gammarids have several adaptations that enable them to invade and persist in habitats experiencing common water level fluctuations.

WOS: 000299017200011, To date, 13 amphipod species [Dikerogammarus haemobaphes (Eichwald, 1841); D. istanbulensis Ozbek & Ozkan, 2011; D. gruberi Mateus & Mateus, 1990; Echinogammarus ischnus Stebbing, 1899; Pontogammarus robustoides (Sars, 1894); P. maeoticus (Sowinsky, 1894); P. aestuarius (Derzhavin, 1924); Obesogammarus turcarum Stock, 1974; Amathillina cristata Sars, 1894; Chelicorophium curvispinum Sars, 1895; C. maeoticum (Sowinsky, 1898); C. robustum Sars, 1895 and Orchestra cavimana Heller, 1865] were reported from Turkey as the representatives of Ponto-Caspian amphipod fauna. Previous records and current distributional patterns of Ponto-Caspian amphipod crustaceans in Turkish inland waters were investigated. Three new localities were revealed as one of the southernmost points in distributional area of Pontogammarus robustoides (Sars, 1894).

Based on original data (450 samples from 115 streams of European Russian middle latitudes—from Pskov to Kostroma regions), an attempt is made to describe the diversity of rheophilic communities inhabiting stream bottoms and macrophytes. A total of 39 community types are identified by the Braun-Blanquet method. Their taxonomical and structural characteristics are described, the associations with biotopes are outlined, and a biotopical nomenclature is proposed. All communities are subdivided into four biotopical classes: crenal (springs and springbrooks with mixed substrates), rhitral (stony and woody substrates), phythal (macrophytes), and pelal (soft ground). It is shown that all communities can be divided by their organization into P-type or M-type communities. Thirty-six out of 39 studied communities belong to the P-type and are characterized mainly by the prevalence of insects, unstable dominance, and rather distinct association with the biotope. In M-type communities (3 out of 39 studied communities), the eurybiontic mollusk Viviparus viviparus and amphipod Dikerogammarus haemobaphes predominate; these communities are interbiotopic, with a stable species structure and high total abundance. The effect of the study’s spatial scale on the definition of communities is discussed along with problems of the communities’ dynamics.

Temperature is a crucial factor determining biology and ecology of poikilothermic animals. It often constitutes an important barrier for invasive species originating from different climate zones but, on the other hand, may facilitate the invasion process of animals with wide thermal preferences and high resistance to extreme temperatures. In our experimental study, we investigated the thermal behaviour of two Ponto-Caspian amphipod crustaceans—Dikerogammarus villosusandDikerogammarus haemobaphes. Both species are known to live under a wide range of thermal conditions which may promote their invasion. Moreover, both these amphipods are hosts for microsporidian parasites which co-evolved with them within the Ponto-Caspian region and spread in European waters. As the presence of a parasite may influence the thermal preferences of its host, we expected to observe behavioural changes in infected individuals of the studied amphipods leading to (1) behavioural fever (selecting a warmer habitat) or (2) anapyrexia (selecting a colder habitat). The experiment (N = 20) was carried out for 30 min in a 100 cm. 20 cm from boths sides were not avaliable for amphipods long thermal gradient (0–40 °C), using 30 randomly selected adult amphipod individuals of one species. At the end of each trial, we checked the position of amphipods along the gradient and determined their sex and infection status (uninfected or infected by one of microsporidium species).D. villosuswas infected withCucumispora dikerogammariwhereasD. haemobapheswas a host forC. dikerogammari,Dictyocoela muelleriorD. berillonum. Thermal preferences of amphipods depended on their species and sex. Females ofD. villosuspreferred warmer microhabitats (often much above 30 °C) than conspecific males and females ofD. haemobaphes, whereas no significant differences were found among males of both species and both sexes ofD. haemobaphes. Moreover, infected males ofD. villosusstayed in warmer water more often than uninfected males of this species, selecting temperatures higher than 30 °C, which may be explained either as a behavioural fever constituting a defence mechanism of a host against the infection, or as a parasite manipulation of the host behaviour increasing the parasite fitness. On the other hand, none of the parasite species affected the thermal preferences ofD. haemobaphes, including alsoC. dikerogammari, changing the behaviour ofD. villosus. Our research presents the complexity of the thermal behaviour of studied amphipods and the evidence that microsporidia may trigger a change in temperature preferendum of their host species and those observations may be the result of different host-parasite coevolution time which may vary for the two host species (Poulin, 2010).

A Ponto-Caspian amphipod Dikerogammarus haemobaphes has recently invaded European waters. In the recipient area, it encountered Dreissena polymorpha, a habitat-forming bivalve, co-occurring with the gammarids in their native range. We assumed that interspecific interactions between these two species, which could develop during their long-term co-evolution, may affect the gammarid behaviour in novel areas. We examined the gammarid ability to select a habitat containing living mussels and searched for cues used in that selection. We hypothesized that they may respond to such traits of a living mussel as byssal threads, activity (e.g. valve movements, filtration) and/or shell surface properties. We conducted the pairwise habitat-choice experiments in which we offered various objects to single gammarids in the following combinations: (1) living mussels versus empty shells (the general effect of living Dreissena); (2) living mussels versus shells with added byssal threads and shells with byssus versus shells without it (the effect of byssus); (3) living mussels versus shells, both coated with nail varnish to neutralize the shell surface (the effect of mussel activity); (4) varnished versus clean living mussels (the effect of shell surface); (5) varnished versus clean stones (the effect of varnish). We checked the gammarid positions in the experimental tanks after 24 h. The gammarids preferred clean living mussels over clean shells, regardless of the presence of byssal threads under the latter. They responded to the shell surface, exhibiting preferences for clean mussels over varnished individuals. They were neither affected by the presence of byssus nor by mussel activity. The ability to detect and actively select zebra mussel habitats may be beneficial for D. haemobaphes and help it establish stable populations in newly invaded areas.

Dikerogammarus haemobaphes is a Ponto-Caspian gammarid that has invaded vast areas in Central and Western Europe. Our paper is a first presentation of its life history features in an invaded region. The study was conducted in the Vistula River in Poland from autumn 2003 to autumn 2005 in two sites differing in hydrological conditions with one being water reservoir. The results showed that the reproductive period lasted 8 months from April till October in both sites. Three generations per 1 year were observed: autumn (overwintering), spring and summer. Ten cohorts per year were distinguished. The individuals from the reservoir were much bigger than those from the other site. The fecundity of those specimens was also higher and they laid 52 eggs per clutch in average in comparison with 37 eggs in the river itself. The strong relationship between the number of embryos (in developmental stage 2) per clutch and the length of females was noticed. The overall mean egg size of stage 2 of D. haemobaphes was 0.430 ± 0.029 mm which is smaller than noted for native species such as Gammarus fossarum. A potentially high reproductive capacity, comparatively small eggs, short time of eggs’ development, fast reaching sexual maturation, short life span, tolerance to a wide range of environmental conditions, all promote the invasion of this Ponto-Caspian gammarid in freshwater ecosystems of the temperate climate zone.

The Wloclawek Dam Reservoir located on the lower Vistula River (central Poland) is part of the central corridor used by Ponto-Caspian species to migrate in Europe. It provides a number of habitats suitable for sustaining populations of several non-indigenous taxa. Four Ponto-Caspian amphipod species were recorded in the reservoir: Chaetogammarus ischnus, Chelicorophium curvispinum, Dikerogammarus haemobaphes and Pontogammarus robustoides. We found significant differences in amphipod densities and species composition among various microhabitats in off-channel areas. P. robustoides was the only amphipod species that occurred on very shallow (< 1 m) sandy bottom near the shore. It inhabited also other sites but its share in the total number of amphipods and abundance decreased with the distance from the shore. Furthermore, at sites more distant from shore its affinity for plant substratum was higher. D. haemobaphes, C. ischnus and C. curvispinum clearly preferred sites distant from shore, overgrown by macrophytes or covered by mussel shells. Furthermore, the abundance of C. ischnus was negatively correlated with the presence of P. robustoides.

About six life history and two ecological traits of gammarid species occurring in Central European waters were compared in order to identify the characters of successful invader. The species were (1) natives: Gammarus fossarum, G. pulex, G. lacustris, G. varsoviensis, G. balcanicus, G. leopoliensis, G. roeselii, and (2) aliens: Gammarus tigrinus, Chaetogammarus ischnus (=Echinogammarus ischnus), Pontogammarus robustoides, Obesogammarus crassus, Dikerogammarus haemobaphes, D. villosus. Generally the alien species were characterised by a combination of large brood size, high partial fecundity, early maturation and by appearance of higher number of generations per year. Also, these species presented higher tolerance towards severe environmental conditions, i.e. elevated salinity and human degradation of the environment. The above features seem to facilitate the colonisation of new areas and competition with native species -- a phenomenon that has been currently observed in various parts of Europe.

Since the middle of the 20th century, six species of Ponto-Caspian amphipods (Chaetogammarus ischnus, C. warpachowskyi, Chelicorophium curvispinum, Dikerogammarus haemobaphes, Obesogammarus crassus, Pontogammarus robustoides), one Baikalian amphipod Gmelinoides fasciatus and one amphipod of Atlantic origin Gammarus tigrinus have expanded in Russia and adjacent regions. A wide variety of human mediated vectors such as deliberate and accidental introductions, natural migration via constructed inland waterways and high rates of spread, survival and reproduction in these species have facilitated rapid dispersal and successful establishment of these alien species. Causes of successful establishment of these invaders and potential consequences of the invasions including extinctions of native species in rivers, lakes and estuaries of north-western Russia are discussed.

Among ca. 750 species of Crustacea recorded from Poland, 18 representatives of 5 orders of macro-crustaceans have been identified as alien species that have invaded or have been introduced to Polish waters. Out of 44 freshwater, brackishwater and semiterrestrial species of Amphipoda occurring in Poland (not counting several stygobiotic species), 8 species from three families may be included in this group. They are Corophiidae: Chelicorophium curvispinum (=Corophium curvispinum), Gammaridae: Gammarus roeselii, G. tigrinus, Chaetogammarus ischnus (=Echinogammarus ischnus), Pontogammaridae: Dikerogammarus haemobaphes, D. villosus, Pontogammarus robustoides and Obesogammarus crassus. It is noticeable that most of them (C. curvispinum, C. ischnus, D. haemobaphes, D. villosus, P. robustoides, O. crassus) are of Ponto-Caspian origin, one species was introduced from North America (G. tigrinus), and one from south-eastern Europe (G. roeselii). All the species listed above have spread widely in Poland, in large rivers and artifical reservoirs (Chelicorophium curvispinum, Dikerogammarus villosus, D. haemobaphes, Pontogammarus robustoides, Gammarus tigrinus) or in medium sized rivers (Gammarus roeselii), in brackish coastal waters (Obesogammarus crassus) or both in fresh and brackish waters (Gammarus tigrinus, Pontogammarus robustoides). In most places they successfully outnumber or even completely replace native amphipod species. This paper presents data on biogeography, history, biology and ecology of alien species, as well as the consequences of their invasion in Poland with an extended bibliography and references to other European countries.

During a survey of the Belarusian part of the Dnieper River conducted on 19-22 July 2006, we revealed five invasive Ponto-Caspian amphipod species in its benthos community: Chaetogammarus ischnus, Chelicorophium curvispinum, Dikerogammarus haemobaphes, Dikerogammarus villosus and Pontogammarus robustoides. All of them except C. curvispinum are reported in Belarus for the first time. The number of alien amphipod species and their abundance were found to decrease gradually in the upper sections of the river.

The gammarid composition at 25 sites in the rivers Danube, Main and the southern reaches of the Rhine were studied during the years 2002–2004. Dikerogammarus villosus and Echinogammarus ischnus were the most frequent species prevailing at 17 sites. Sympatric occurrence of D. villosus and E. ischnus was observed at 12 sites. Dikerogammarus haemobaphes was recorded at 7 sites; this species prevailed in the Danube, west of the Weltenburger Enge and in the Isar mouth where it co-existed with native species (Gammarus pulex and/or G. roeseli) at 6 sites. Dikerogammarus bispinosus and E. berilloni were found at only 1 site, where they co-existed with D. villosus and E. ischnus, and with D. villosus and native species, respectively. Investigation of reproductive characteristics at 3 sites showed that females of D. villosus and D. haemobaphes produced the biggest clutches with more than 100 eggs. Females of E. ischnus produced much smaller clutches (10–35 eggs on an average), but very big eggs. Clutch sizes and egg volumes of D. bispinosus and E. berilloni resembled those of native species. Our results suggest that the most successful invaders (D. villosus, D. haemobaphes and E. ischnus) display reproductive traits that facilitate their success. Both Dikerogammarus sp. allocate energy into production of many but small eggs, thus maximizing offspring number, while E. ischnus allocates its energy into production of fewer but large eggs which could be beneficial at sites where food is scarce.

This study has shown that Pontogammarus robustoides has a multivoltine life cycle in central Poland, with three generations per year (spring, summer, and autumn). Reproduction lasts from March/April until October, when the last breeding females are found. The first juveniles appear in May and are present in the population until the end of October. Spring and summer generations mature in a very short time (4–5 weeks). Females born in May and July start breeding at a body length of 8.5 mm, whereas the length of overwintering females breeding in spring ranges 11–18 mm. The number of eggs laid is exponentially correlated with the size of a female (r2= 0.89).

During the last decade of 20th century, the nonindigenous gammarid species Gammarus tigrinus, Dikerogammarus haemobaphes, Pontogammarus robustoides and Obesogammarus crassus invaded the lower Vistula River and its deltaic, partly brackish regions. G. tigrinus, an oligohaline North-American species, was introduced to western Europe in the 1950s; the remaining three species are oligohaline/freshwater Ponto-Caspian species. All these species are now invading central and western Europe using the network of man-made canals connecting different European river systems. In the Vistula River, the native European freshwater gammarid species Gammarus pulex and G. varsoviensis were replaced in the 1920s by the Ponto-Caspian Chaetogammarus ischnus (syn. Echinogammarus ischnus), which in turn has been outnumbered by the more recent invasions of D. haemobaphes and P. robustoides. In brackish waters, the native Atlantic-boreal species Gammarus zaddachi and Gammarus duebeni are replaced or at least outnumbered by G. tigrinus, P. robustoides and O. crassus. Possible invasion routes are discussed.

A Ponto-Caspian gammarid – Dikerogammarus haemobaphes – a recent invader of the Vistula and Oder rivers, appeared also in Great Masurian Lakes. Possible routes of its invasion are discussed.

SUMMARY 1. Biological invasions often involve close taxonomic relatives either as native/invader pairs or as invader/invader pairs. Precise identification and differentiation of species is therefore of paramount importance to reconstruct the invasion history. Genetic studies are indispensable in the case of morphologically conservative taxonomic groups. 2. We analysed the Pontocaspian freshwater amphipods Dikerogammarus that have successfully invaded the benthos of large Central European rivers. Taxonomic uncertainties were clarified by phylogenetic analyses of mitochondrial 16S and COI genes. The three-way partitioning of allozyme genotypes in a syntopic population further corroborated the taxonomic status of the three species Dikerogammarus haemobaphes, D. villosus and D. bispinosus. Dikerogammarus bispinosus had been prior misidentified as a subspecies of D. villosus. The conspicuous colour types of D. villosus, however, appeared to be conspecific. 3. The genetic identification of the previously more abundant D. haemobaphes individuals in old samples supported the ‘successive invasion wave’ hypothesis with D. haemobaphes as the first invader displaced by the second invader D. villosus. Dikerogammarus bispinosus could be a potential future invader. 4. Haplotype differentiation was apparent between two invasion lines of D. haemobaphes, but the occurrence of a single widespread haplotype indicates genetic impoverishment during rapid colonisation.

As the tempo of biological invasions increases, explanations and predictions of their impacts become more crucial. Particularly with regard to biodiversity, we require elucidation of interspecific behavioural interactions among invaders and natives. In freshwaters in The Netherlands, we show that the invasive Ponto-Caspian crustacean amphipod Dikerogammarus villosus is rapidly eliminating Gammarus duebeni, a native European amphipod, and Gammarus tigrinus, until now a spectacularly successful invader from North America. In the laboratory, survival of single (unguarded) female G. duebeni was significantly lower when male D. villosus were free to roam as compared with isolated within microcosms. In addition, survival of paired (guarded) female G. duebeni was significantly lower when male D. villosus as compared with male G. duebeni were present. D. villosus killed and consumed both recently moulted and, unusually, intermoult victims. Survival of G. tigrinus was significantly lower when D. villosus were free to roam as compared with isolated within microcosms and, again, both moulted and intermoult victims were preyed upon. Male D. villosus were significantly more predatory than were females, while female G. tigrinus were significantly more often preyed upon than were males. Predation by D. villosus on both species occurred over a range of water conductivities, an environmental feature previously shown to promote amphipod coexistence. This predatory invader is predicted to reduce further the amphipod diversity in a range of freshwater habitats in Europe and North America.

The river Odra estuary belongs to those water bodies in the Baltic Sea area which are most exposed to immigration of alien species. Non-indigenous species that have appeared in the Szczecin Lagoon (i.a. Dreissena polymorpha, Potamopyrgus antipodarum, Corophium curvispinum) and in the Pomeranian Bay (Cordylophora caspia, Mya arenaria, Balanus improvisus, Acartia tonsa) in historical time and which now are dominant components of animal communities there as well as other and less abundant (or less common) alien species in the estuary (e.g. Branchiura sowerbyi, Eriocheir sinensis, Orconectes limosus) are presented. In addition, other newcomers - Marenzelleria viridis, Gammarus tigrinus, and Pontogammarus robustoides - found in the estuary in the recent ten years are described, The significance ofthe sea and inland water transport in the region for introduction of non-indigenous species is discussed against the background of the distribution pattern of these recently introduced polychaete and gammarid species.

Since the first finding in 1853 (Frivaldszky, 1865), 27 Amphipoda have been reported from Hungary, half of them being Niphargus species. The other amphipod species belong to the genera Gammarus, Dikerogammarus, Echinogammarus, Corophium, Synurella, Orchestia, and Talitrus. The most detailed data are available from Lake Balaton where altogether 8 species were found in different habitats, only a few species occurring together. In the 1930s Corophium curvispinum invaded Lake Balaton. This species was reported from Hungary for the first time in 1916 (from the Danube). In the 1950s Dikerogammarus species replaced Gammarus roeselii in the lake. We investigated the ecology of the Amphipoda fauna in Lake Balaton from 1983 to 1987. Both on the submerged macrophytes and in the stony littoral zone of Lake Balaton Corophium curvispinum, Dikerogammarus haemobaphes, and Dikerogammarus villosus occur, with dominancy of Corophium curvispinum. C. curvispinum and D. haemobaphes, living on the submerged macrophyte Myriophyllum spicatum near Tihany peninsula, reproduce in late spring, summer, and early autumn. They produce two generations a year. The biomass of C. curvispinum and D. haemobaphes was roughly 11 and 0.1 g animal dry wt.m -2 , respectively, in mid-July 1986, in areas covered by Myriophyllum spicatum.

Rijeka Sava je najduža rijeka u Hrvatskoj (duljine 940 km). Nastaje spajanjem Save Dolinke i Save Bohinjke u blizini Lancova u Sloveniji te pripada slivu Crnoga mora. U ovome radu prikazani su rezultati ribarskoga istraživanja rijeke Save u svome toku kroz Hrvatsku u 2010. godini. Istraživanjima koja su provedena u srpnju i listopadu praćene su fizikalno-kemijske osobine, kvalitativan i kvantitativan sastav te biološka raznolikost makrobentosa rijeke Save. Bentos označava stanovnike dna, organizme koji naseljavaju različite supstrate dna voda barem dijelom svoga života.Biološka raznolikost makrobentosnih zajednica određena je pomoću Simpsonovog, Margalefovog i Shannon-Weaveovog indeksa.Temeljem analize otopljenog kisika u vodi, utvrđeno je da rijeka Sava ima polioksitipsko obilježje. Prema vrijednostima otopljenog kisika, lokacije Medsave i Zagreb sa vrijednostima većim od 7 mg/l pripadaju vodama I vrste. Na većini lokacija voda pripada III vrsti. Izuzetak su Lijevi Dubrovčak gdje voda pripada IV vrsti te lokacije Ivanja Reka i Županja gdje je zabilježen režim kisika značajan za vode V vrste. Uzorkovanje makrobentosa provedeno je na deset lokacija. Najveća raznolikost vrsta prema Margalefovom indeksu bila je na lokaciji Zagreb, a indeks je iznosio 2, 37. Najmanja raznolikost vrsta zabilježena je u listopadu također na području Zagreba, gdje su Margalefov indeks raznolikosti i Shannon-Weaverov indeks iznosili 0, a Simpsonov indeks je iznosio 1. Prema razvijenosti makrobentosa u rijeci Savi najviše se razvilo pripadnika skupine Gammarus sp., Trichoptera, Gastropodas vrstama Viviparus viviparus i Lithoglyphus naticoides, Chironomidae, Oligochaeta, Hirudinea. Na području Radatović pronađeni su invazivni Amphipoda Dikerogammarushaemobaphes koji su tek nedavno naselili ovo područje.

International audience; In Europe, the number of establishment of non-native species, especially from Ponto-Caspian area, has dramatically increased over the past decades and induced important changes in macroinvertebrate assemblages, mainly in large rivers. However, although many Ponto-Caspian species were established in adjacent countries, only two Ponto-Caspian amphipods were formally observed in French hydrosystems since 1996. To update our knowledge on the present distribution of the Ponto-Caspian species in France, we collected amphipods from 203 sites in the Rhine, Meuse and Seine River basins in 2008 and again in 2009. Thirteen amphipod species were found in the study area. Among them, four were first formally recorded in France (Dikerogammarus haemobaphes, Dikerogammarus bispinosus, Echinogammarus ischnus, and Echinogammarus trichiatus). Our study revealed three different corridors used by these species to arrive in France. We also observed a different pattern of colonization for each species, which might indicate some between-species differences in their preferences for environmental conditions. The snapshot of the early distributions of these recently established species may hence be used to study the invasion pattern in France in order to manage their potential impact in and outside France.

Samples issued from intensive sampling in the Netherlands (1992–2001) and from extensive sampling carried out in the context of international campaigns (1998, 2000 and 2001) were revisited. Additional samples from artificial substrates (1992–2003) and other techniques (various periods) were analysed. The combined data provide a global and dynamic view on the Peracarida community of the River Meuse, with the focus on the Amphipoda. Among the recent exotic species found, Crangonyx pseudogracilis is regressing, Dikerogammarus haemobaphes is restricted to the Condroz course of the river, Gammarus tigrinus is restricted to the lowlands and seems to regress, Jaera istri is restricted to the ‘tidal’ Meuse, Chelicorophium curvispinum is still migrating upstream into the Lorraine course without any strong impact on the other amphipod species. After a rapid expansion Dikerogammarus villosus has continued its upstream invasion between 1998 and 2002 at a rate of 30–40 km per year, but no further progression was noticed in 2003. Locally and temporarily the native species (Gammarus fossarum and G. pulex) and naturalized species (G. roeseli and Echinogammarus berilloni) may have been excluded by the most recent invaders (mainly D. villosus), but none of the native and naturalized species has disappeared completely. Therefore, the number of amphipod species found in the River Meuse has increased. Moreover, the native and naturalized species keep on dominating the tributaries from which the recent invaders seem to be excluded. A changing Peracarida community structure is observed along the course of the River Meuse: four native or naturalized species inhabit the upstream (Lorraine) course, three invasive species dominate in the middle reach (Ardenne-Condroz zone), one exotic species is housed in the Border Meuse and three or four invasive species dominate the assemblages in the lowlands.