Monkey Goby Neogobius Fluviatilis Research Articles

Non-native Ponto-Caspian Gobies in the mouths of the Vistula River tributaries

At present, four non-native gobiid species (racer goby Babka gymnotrachelus, monkey goby Neogobius fluviatilis, round goby Neogobius melanostomus and western tubenose goby Proterorhinus semilunaris) are listed as occurring in the Vistula River of Poland. In this work, the distribution and densities of gobiids in the river-mouth stretches of the Vistula tributaries flowing downstream from the Włocławek Reservoir in the Baltic Sea direction are presented. The fish were collected by electrofishing from a boat or while wading. Non-native gobiids were noted in 15 of the 18 tributaries studied. Among the 1,075 gobies caught, the western tubenose goby was the most common and occurred in 15 of the sites examined. The racer goby was registered in seven of the tributaries, while the monkey goby was recorded in only three. No round goby was caught. The highest densities of the western tubenose goby and racer goby were noted in the small stream located directly downstream from the Włocławek Reservoir. Among the species identified, the western tubenose goby seems to be more eurytopic because it was the last of these species to invade the Vistula River, but it is now the most widespread. In addition to a morphological identification of the fish, samples of each species were confirmed by an analysis of subunit I of the cytochrome oxidase (COI) barcode sequences. The genetic analysis of the COI subunit revealed that this sequence is effective for the taxonomic differentiation of the Ponto-Caspian gobies occurring in Poland. The results showed that gobiids have become a permanent element of the ichthyofauna of the Vistula and its tributaries that are available for migration Key words: invasive species, Gobiidae, Neogobius fluviatilis, Babka gymnotrachelus, Proterorhinus

Differences in predator-avoidance behavior between two invasive gobies and their native competitors.

Globally, fish are frequently introduced beyond their native range. Some, like Ponto-Caspian gobies, are becoming invasive, achieving high colonization rates and constituting frequent prey for native predators. However, little is known about the effectiveness of antipredator behaviors of the invaders, which may shape their role in the invaded community and contribute to the invasion success. We compared antipredator behaviors of invasive gobies and native fish species after their detection by the predator, when the danger becomes direct. We studied 2 fish pairs, each consisting of an invasive and native species co-occurring in the environment and belonging to the same prey guild: (1) the racer goby Babka gymnotrachelus versus European bullhead Cottus gobio, (2) the monkey goby Neogobius fluviatilis versus gudgeon Gobio gobio, facing a naïve predator (the Eurasian perch Perca fluviatilis). We analyzed behaviors of single prey individuals (escaping, staying in shelter, and activity) and single predators (activity, searching, following, capturing, and latency to prey consumption). In the predator presence, the bullhead was less active and more often managed to escape after capture than the racer goby. The gudgeon escaped before the capture more often than the monkey goby. The predator succeeded later with the bullhead compared to racer goby, whereas no differences in ingestion time occurred between the gudgeon and monkey goby. The results suggest that, in terms of hunting effort of native predators, the invasive gobies are equivalent to or more profitable prey than their native analogs, which can facilitate the integration of the gobies into local food webs.

Daily and seasonal dynamics of littoral zone fish communities in the lowland Włocławek Reservoir (central Poland), with a special emphasis on alien invasive gobies

The aim of the study was to examine the daily and seasonal dynamics of changes in fish communities in two environmentally different littoral zones of the Włocławek Reservoir (central Poland), i.e., the floodplain (limnic Dobiegniewo site) and lotic area (Murzynowo site). During seasonal catches using trawl nets, in the daily cycle (at 00.00, 06.00, 12.00, and 18.00 hours), the presence of 18 fish species representing 4 families (Cyprinidae, Percidae, Gasterosteidae, Gobiidae) was confirmed. In both localities, the domination of native taxa, such as roach Rutilus rutilus (L.) and Eurasian perch Perca fluviatilis L., in Dobiegniewo (26.6 and 26.6%, respectively) and Murzynowo (13.6 and 22.7%, respectively) of all caught specimens was noted. The quantitative share of three alien invasive gobies, racer goby Neogobius gymnotrachelus (Kessler, 1857), monkey goby Neogobius fluviatilis (Pallas, 1814), and western tubenose goby Proterorhinus semilunaris (Heckel, 1837), varied in the range between 2.7 and 35.3% in samples throughout the season. The results indicate the significant role of gobies in the structure of the sublittoral fish communities of Włocławek Reservoir and the necessity of expansion process studies, as well as the observation of the interactions with native fish species in invaded areas.

Інвазивні види риб у річках басейну Західного Бугу в межах України

Purpose. To determine the occurrence of invasive fish species in ichthyofauna of rivers of the Western Bug basin in Ukraine. Methodology. Ichthiological studies were carried out during 2019-2021 in the Western Bug River and on its tributaries - Rata, Bushkov, Poltva and Mlynivka. Fish species identification was carried out in situ and was performed according to the identification keys of Yu.V. Movchan and A.F. Koblytska, incomplete biological analysis of invasive species was performed in the laboratory according to the methods of I.F. Pravdin, G.V. Nikolsky and I.I. Chugunova. Findings. The obtained data showed that invasive species in the composition of ichthyofauna in the studied rivers of the Western Bug basin were represented by five species: Prussian carp Carassius gibelio (Bloch, 1782), Stone moroko Pseudorasbora parva (Temminck & Schlegel, 1846), Pumkinseed Lepomis gibbosus (Linnaeus, 1758), Chinese sleeper Perccottus glenii Dybowski, 1877, Monkey goby Neogobius fluviatilis (Pallas, 1814). These species entered the ecosystem due to human activities through deliberate or accidental introduction into rivers of the Western Bug basin, where conditions are quite favorable for their vital activity and growth, due to a fairly warm climate and changes in hydrological regime of many rivers as a result of human impact. Originality. The article presents for the first time a list of invasive fish species of rivers of the Western Bug basin in Ukraine and provides a description of their habitats. Practical value. The obtained results can be used to regulate recreation fishery, for planning of conservation measures for rare fish species and for planning prevention of negative consequences from the spread of invasive fish species. Key words: ichthyofauna, the Western Bug River, invasive alien species, Prussian carp, Stone moroco, Pumkinseed, Chinese sleeper, Monkey goby.

Behavioural responses to con- and heterospecific alarm cues by an alien and a coexisting native fish

The monkey goby Neogobius fluviatilis is an invasive Ponto-Caspian fish that enters habitats of the native gudgeon Gobio gobio in European freshwaters, likely belonging to the same prey guild. Their abilities to detect and avoid predation have been poorly understood, although these traits may contribute to the competitive advantage and drive the invasion success of the goby. We tested intra- and interspecific responses of fish from sympatric populations to damage-released alarm cues (skin extract) in laboratory. Both species of fish responded to conspecific and heterospecific cues, but their responses to conspecifics were more diverse (changed social distancing among individuals, reduced vertical and horizontal movement) than those elicited by heterospecifics (changed social distancing only). Moreover, the fish differed in their anti-predation behaviour: the gudgeon increased whilst the monkey goby decreased inter-individual distances and only the gudgeon exhibited thigmotaxis and reduced mobility in response to the conspecific cues. Interspecific differences show that the species exhibit distant anti-predation strategies. This might be associated with their phylogenetic distance and/or higher differentiation of their ecological niches than commonly assumed. Besides, our results suggest that alien species be included in the interspecific exchange of information in local fish assemblages.

The First Data on Parasites of Monkey Goby Neogobius fluviatilis (Perciformes, Gobiidae) in the Saratov Reservoir

The parasite fauna of the monkey goby Neogobius fluviatilis has been studied from the lower part of the Saratov Reservoir. Six species of parasites are recorded, for one of which (the goby-specific plerocercoid Triaenophorus crassus) the monkey goby is recorded as an additional host for the first time. The 100% invasion of the goby by the alien fluke Nicolla skrjabini makes it possible to attribute it to the main definitive hosts of the parasite in the water body.

Environmental factors associated with the occurrence of the Ponto–Caspian gobies in a lowland river belonging to the central European invasion corridor

AbstractPonto–Caspian goby fish belong to the most successful invaders in freshwater ecosystems of Europe and North America. So far, three alien goby species have been present in the Polish section of the Dnieper–Rhine River corridor: the monkey goby Neogobius fluviatilis, the racer goby Babka gymnotrachelus, and the western tubenose goby Proterorhinus semilunaris. Their assemblages in this region are unique because, in contrast to their native region or the Danube–Rhine corridor, they are unaffected by other gobiid species. We conducted electrofishing and habitat quality surveys to gather information on key environmental factors associated with the distribution of these fish in the lower river Vistula, which constitutes a vast middle part of the corridor used by the Ponto–Caspian species to migrate westward in Europe. We showed that the sandy bottom was beneficial for the monkey goby allowing the species to attain the highest abundance among the gobies in the river. Habitat complexity generated by artificial bank structures, as well as dense macrophyte coverage in the main channel, favoured mostly the expansion of the racer goby. Off‐channel areas with vegetation and a muddy bottom (old river beds and pools) were the most suitable habitats for the western tubenose goby. We did not find any negative spatial relationships among gobies of various species and sizes except the avoidance of the monkey goby by small western tubenose goby. Thus, our study demonstrates substantial habitat partitioning, suggesting a low level of interspecific competition among the three species in a lowland river.

Plasticity in the feeding ecology of native Ponto‐Caspian gobies suggests establishment success in their nonnative range

AbstractThe feeding ecology of the two gobiid species monkey goby Neogobius fluviatilis and western tubenose goby Proterorhinus semilunaris was studied in four natural lakes of the Marmara Region (NW Turkey), with special emphasis on seasonal and ontogenetic shifts in diet. Both species had similar food composition consisting of zooplankton and detritus. However, diet composition of both species significantly varied amongst lakes, and particularly so for P. semilunaris with seasonal and ontogenetic differences. Diet composition and seasonal/ontogenetic differences were overall similar to other populations of these gobiid species from both their native and nonnative ranges. The present findings suggest high plasticity in the diet of these two gobies, which can opportunistically utilize available food resources.

Plasticity in habitat use of two native Ponto-Caspian gobies, Proterorhinus semilunaris and Neogobius fluviatilis: implications for invasive populations

The Ponto-Caspian region is an important source area for some invasive gobiid fishes. These fishes have colonised several freshwater ecosystems in Europe, as well as in North America. As knowledge on their habitat utilisation in their native range remains limited, the seasonal habitat uses of Western tubenose goby, Proterorhinus semilunaris and monkey goby Neogobius fluviatilis were studied in four natural lakes in the Marmara Region (NW Turkey). Habitat use of both species was highly variable between the lakes and seasons, with P. semilunaris showing higher plasticity. In general, the main habitats used by P. semilunaris were shallow waters in littoral areas that had vegetation cover, whereas N. fluviatilis consistently used sandy substratum in deeper waters that lacked vegetation. These results suggested there was high plasticity in the habitat utilisation of these two gobiids, especially in P. semilunaris, which potentially facilitates their ability to establish and invade novel environments. The habitats that are especially vulnerable to P. semilunaris invasion are medium size substrates which provide individuals with sufficient interstitial space for refuge. Waters providing differing habitats, such as sandy substrata, might inhibit their colonisation, but are potentially more vulnerable to N. fluviatilis invasion.

МЕТОДИКА ОЦЕНКИ КАЧЕСТВА ВОДЫ С ПОМОЩЬЮ ПОВЕДЕНЧЕСКИХ РЕАКЦИЙ РЫБ

The proposed technique of water quality assessment is intended for monitoring and measuring the behavioral responses of fishes in minimally structured environment, and further evaluating the reactivity of the fish nervous system. Tests were conducted in the period from 11 May to 7 June, 2016 at the sea coast station of the Southern Scientific Center of the Russian Academy of Sciences (Kagalnik village, the Rostov region). As test-objects (bioindicators), there were selected three species of gobies: round goby ( Neogobius melanostomus ), monkey goby ( Neogobius fluviatilis ) and goby Shearman ( Neogobius syrman ). Fish behavior was assessed by response to external stimuli, which is manifested by increased or decreased locomotor activity. Expected and phone activity has been defined. As the test stimuli there were used: a low-frequency sonic boom, a sinusoidal audio signal, a high-frequency sonic boom, an electrical stimulus. Testing water samples were taken from three stations in the water area of the Gulf of Taganrog (estuary of the Don, middle section of the bay and section of the river close to the coastal base). The results showed that the developed method is sensitive to changes of natural water pollutants and can be used in the monitoring system, as a component for coastal stations on the test areas of the Azov Sea in terms of bioindication data matching techniques to identify natural and anthropogenic sources of pollution.

Proteolytic activity in some freshwater animals and associated microflora in a wide pH range.

Proteolytic activity in some freshwater animals (crustacean plankton, sandhopper Amphipoda sp., larvae of chironomids Chironomus sp., oligochaetes Oligohaeta sp., dreissena Dreissena polymorpha, roach Rutilus rutilus heckelii, rudd Scardinius erythrophthalmus, ruff Acerina cernua, and monkey goby Neogobius fluviatilis) prevailing within the food of fishes of various ecological groups as well as in their associated microflora in a wide pH range was investigated. It has been shown that the optimum pH of proteases in the animals' whole organism varies: 6.0 for sandhopper; 8.0 for chironomid larvae, oligochaetes, monkey goby, and ruff; 8.0-9.0 for zooplankton; and 10.0 for roach and rudd. The optimum pH of associated microflora proteases is 6.0 for monkey goby; 7.0 for sandhopper and roach and ruff ; 8.0-9.0 for oligochaetes; 9.0 for zooplankton; and 10.0 for chironomid larvae and rudd. The compensatory role of food items and enteric microbiota proteases in digestive processes in fish of different ecological groups at low pH is discussed.

The Review of Ecological and Genetic Research of Ponto-Caspian Gobies (Pisces, Gobiidae) in Europe

Abstract Invasive Ponto-Caspian gobies (monkey goby Neogobius fluviatilis, round goby Neogobius melanostomus and bighead goby Ponticola kessleri) have recently caused dramatic changes in fish assemblage structure throughout European river systems. This review provides summary of recent research on their dietary habits, age and growth, phylogenetic lineages and gene diversity. The principal food of all three species is invertebrates, and more rarely fish, which depends on the type of habitat, part of the year, as well as the morphological characteristics of species. According to the von Bertalanffy growth model, size at age is specific for the region, but due to its disadvantages it is necessary to test other growth models. Phylogenetic analysis of monkey goby and round goby indicates separation between the Black Sea and the Caspian Sea haplotypes. The greatest genetic diversity is found among populations of the Black Sea, and the lowest among European invaders. The lack of molecular research on bighead goby requires further studies.

The parasite community of gobiid fishes (Actinopterygii: Gobiidae) from the Lower Volga River region

AbstractThe parasitic fauna in the lower Volga River basin was investigated for four gobiid species: the nonindigenous monkey goby Neogobius fluviatilis (Pallas, 1814), the round goby N. melanostomus (Pallas, 1814), the Caspian bighead goby Ponticola gorlap (Iljin, 1949), and the tubenose goby Proterorhinus cf. semipellucidus (Kessler, 1877). In total, 19 species of goby parasites were identified, of which two - Bothriocephalus opsariichthydis Yamaguti, 1934 and Nicolla skrjabini (Iwanitzki, 1928) - appeared to have been introduced from other geographic regions. The monkey goby had significantly fewer parasitic species (6), but relatively high levels of infection, in comparison to the native species. Parasitism of the Caspian bighead goby, which is the only predatory fish among the studied gobies, differed from the others according to the results of discriminant analysis. The parasitic fauna of the tubenose goby more closely resembled those of Caspian Sea gobiids, rather than the Black Sea monkey goby.

Dietary habits of invasive Ponto-Caspian gobies in the Croatian part of the Danube River basin and their potential impact on benthic fish communities

Invasive Ponto-Caspian (P-C11P-C=Ponto-Caspian; NF=Neogobius fluviatilis; NM=Neogobius melanostomus; PK=Ponticola kessleri; CCA=canonical correspondence analysis; GLM=generalized linear model; n.d.=not determined.) gobies have recently caused dramatic changes in fish assemblage structures throughout the Danube basin. While their presence in the Croatian part of the basin has been noted and distribution studied, their dietary habits and impacts on native fish communities have, until now, been unknown. In 2011, 17 locations in the Sava River Basin were sampled for fish and 15 for benthic invertebrates. Fish population monitoring data, available for nine seasons (2003–2006 and 2010–2014) and 12 locations, were used to analyse the impacts of P-C gobies on benthic fish abundance. Gut content analysis indicates that the monkey goby Neogobius fluviatilis diet is very diverse, but dominated by Trichoptera, Chironomidae, Bivalvia and Odonata. The diet overlaps considerably with the round goby Neogobius melanostomus diet, although Gastropoda are dominant in the latter's diet. Small fish and Gammarus sp. dominate the bighead goby Ponticola kessleri diet. Comparison of gut content with the prey available in the environment indicates that monkey and round gobies exhibit preference for Trichoptera, Megaloptera and Coleoptera, and bighead goby for Trichoptera, Gammarus sp. and Pisces. P-C gobies in the Sava River are spreading upstream, towards the reaches with lower fish diversity. Analyses indicate potentially positive impacts of P-C gobies' presence on some fish populations: round and bighead goby on Balkan golden loach Sabanejewia balcanica and monkey goby on common carp Cyprinus carpio, crucian carp Carassius carassius, burbot Lota lota and Balkan loach Cobitis elongata. However, there are also indications that bighead and round goby could adversely impact the native chub Squalius cephalus and zingel Zingel zingel populations, respectively. As P-C gobies are still in the expansionary period of invasion and the ecosystem still adapting to new circumstances, continued monitoring of fish population dynamics in the Sava basin is needed to determine the outcome and impacts of this invasion.

Environment not ‘nativeness’ dictates reproductive trait shifts in Ponto‐Caspian gobies

Amongst the many theories explaining success of introduced species (e.g., the ‘enemy release theory’, ‘invasional meltdown’ theory), that of ‘alternative ontogenies and invasive potential’ (henceforth AOIP) has recently been put forward as regards invasional success of, amongst others, fish. The theory of alternative ontogenies (Balon 2004) suggests that environmental cues, acting mostly during early ontogeny, can shift an individual (or cohort, as members of each cohort often encounter identical conditions) along a generalised-specialised r-K (or altricial-precocial) gradient of life-history strategies. Several recent studies have widened this theory in relation to invasive biology, resulting in the AOIP theory (e.g., Z ahorsk a et al. 2013; Horkov a & Kov a c 2014). This predicts that (i) the invasive potential of a species is supported by its life-history plasticity, and (ii) that individuals in a recently established invasive population will shift to more altricial strategies (Z ahorsk a et al. 2013). The latter hypothesis predicts higher fecundity, lower size-at-maturity and smaller oocytes in non-native populations (Horkov a & Kov a c 2014). Data from both native and non-native ranges are needed to verify this hypothesis. Such comparative data are still lacking for most invasive species (Parker et al. 2013), however, despite the huge benefits of such comparisons to fundamental hypotheses and principles of invasion biology. One such ‘blank spot’ relates to reproductive traits in invasive Ponto-Caspian gobiids. Five PontoCaspian gobiid species (monkey goby Neogobius fluviatilis, racer goby Neogobius gymnotrachelus, bighead goby Neogobius kessleri, western tubenose goby Proterorhinus semilunaris and the round goby Neogobius melanostomus (Pallas, 1814)) have greatly increased their ranges over recent decades, having spread across several major European river basins, including those of the Danube (beyond their original range), Rhine and Vistula (see Roche et al. 2013 for a review). The aim of this study is to provide missing comparative reproduction data for invasive Ponto-Caspian gobies and to interpret this data in the context of AOIP. The two most commonly used reproductive trait measurements [i.e., absolute fecundity (FA), sizeat-maturity] were compared between native and nonnative populations to test whether gobies in recently invaded areas do indeed shift to a more altricial strategy. To avoid bias connected with using native-area data from published literature [which frequently describe fish sampled from marine environments where growth of gobies is accelerated (Corkum et al. 2004)], we sampled both native and non-native freshwater populations of three goby species (monkey, round and bighead goby). In each case, samples were taken from a single population. Furthermore, a single analyst determined the reproductive traits using identical methodology. Native goby populations were sampled from the Bulgarian stretch of the Danube near the town of Vidin in April 2005 (round and bighead gobies at river km 780–781 and monkey gobies at rkm 790; Table S1, Fig. 1). Non-native populations were sampled from the German Rhine near the town of Rees in April 2011 (rkm 831 for monkey gobies and rkm 844–845 for round and bighead gobies; Table S1, Fig. 1). All non-native populations were at an early stage of settlement; that is, less than five generations from first record in the Rhine (Roche et al. 2013), and both native and non-native populations were sampled before their spawning seasons. Estimated relative abundance at native and non-native sites was 0.3 and 0.58 fish m 1 of shoreline surveyed for round goby,

Correlation between body size and fatty acid and essential amino acid composition of round goby (Neogobius melanostomus) and monkey goby (Neogobius fluviatilis) from the Rhine River (Germany)

In this study correlations between body size and muscle fatty and amino acid content of two species of goby, round goby (Neogobius melanostomus) and monkey goby (Neogobius fluviatilis) caught from river Rhine (Germany) were investigated. Among saturated fatty acids (SFAs), mono- (MUFA) and polyunsaturated fatty acids (PUFAs) only SFAs were significantly higher in round goby than monkey goby (P < 0.05). In general, the correlation between body size of both gobies and the content of most of the individual fatty acids was not significant. In monkey goby, the content of palmitic acid (C16:0) and oleic acid (C18:1 n-9) was positively correlated with weight (r = 0.43) and total length (r = −0.58), respectively, and the content of docosahexaenoic acid (DHA) increased with condition factor (r = 0.50). The content of threonine, arginine, valine, phenylalanine and isoleucine in monkey goby was higher than those of round goby (P < 0.05). In round goby the three essential amino acids arginine, valine and leucine were positively (P < 0.05) correlated with body length, which indicates that longer round gobies are of higher nutritional value.

Parasites of non-native gobies in the Włocławek Reservoir on the lower Vistula River, first comprehensive study in Poland

Key-words: alien species, goby fish, parasite community, Vistula River A parasitological study of Ponto-Caspian gobies, including the monkey goby Neogobius fluviatilis, racer goby Babka gymnotrachelus and tubenose goby Proterorhinus semilunaris, carried out over four years in the lower Vistula River is described. These fish species represent one of the most impressive invasions of European inland waters, connected with the spontaneous, east-to-west intracontinental movement observed in the last two decades. The parasite community consisted of 24 taxa. Typical for racer goby were: Trichodina domerguei, Diplostomum pseudospathaceum, Gyrodactylus proterorhini and glochidia of unionids. The list of parasites typical for monkey goby is supplemented with: Tylodelphys clavata (met.) and Eimeria sp., while the glochidia were rarely detected in this fish host. Holostephanus spp., Apatemon gracilis, Diplostomum gobiorum and glochidia predominated in parasite fauna of tubenose goby. Unlike the other species tested, P. semilunaris was poorly infected with T. domerguei and G. proterorhini. Parasites commonly distributed through native fishes in the observed area prevailed in gobies. Species rare in natives were also numerously represented. In this way, alien fish reinforce populations of those parasites in invaded waters. Parasites dragged to the colonized area (G. proterorhini, Holostephanus spp., A. gracilis and D. gobiorum) complement the community. Larval stages were typical for parasite fauna of all studied gobies.

What's in a name? Taxonomy and nomenclature of invasive gobies in the Great Lakes and beyond

The species identities, scientific names, and relationships of Eurasian gobies that invaded the Laurentian Great Lakes – and other species that are predicted to invade in the future – are evaluated here using recently resolved DNA characters. The Round Goby and the Freshwater Tubenose Goby entered the Great Lakes ca. 1990 via ballast water originating from Black Sea ports. The Round Goby spread extensively throughout the Great Lakes and adjacent rivers, whereas the Freshwater Tubenose Goby recently began to expand its range. Both species also are widely invasive in Eurasia, dispersing via canals and shipping. Several of their relatives – the Monkey, Racer, and Bighead gobies – also are invasive in Eurasia, and are predicted to invade the Great Lakes. We discuss results from phylogenetic analyses of DNA sequences from 4 mitochondrial and nuclear gene regions, and provide a revision of their scientific nomenclature. The Freshwater Tubenose Goby was redefined as Proterorhinus semilunaris, which is markedly different and distinctive from the Marine Tubenose Goby Proterorhinus marmoratus. The genus Neogobius, as formerly defined, contained multiple evolutionary lineages and incorrect scientific names. We thus restricted Neogobius to just 4 species—including the Round Goby Neogobius melanostomus and the Black Sea Monkey Goby Neogobius fluviatilis. Several previously recognized subgenera, which were incorrectly grouped in Neogobius, were elevated to the level of genera. Notably, the Racer Goby became Babka gymnocephalus and the Bighead Goby now is Ponticola kessleri. These changes made the names consistent with their true relationships and species characters, which are essential for identifying and characterizing these gobies in invasive and native habitats.

Discrimination between invasive Ponto-Caspian gobies using a PCR-RFLP method

Summary Accurate identification of invaders, and especially their juveniles and eggs, is a difficult task if several morphologically similar species co-occur. The aim of the study was to develop and test a rapid and cost-effective procedure for identification of five species of invasive gobies occurring in the middle Danube basin, namely round goby Neogobius melanostomus, bighead goby Ponticola kessleri, monkey goby Neogobius fluviatilis, racer goby Babka gymnotrachelus and tubenose goby Proterorhinus semilunaris. First, a 708 bp fragment of the cytochrome oxidase I gene was amplified and sequenced for representative samples of these five species. Appropriate sequences of the five species available in public databases were used for in silico analysis. A digestion of the amplified fragment with the BfaI enzyme was found to be suitable for the species identification, as it showed unique restriction patterns for each species. The technique was also successfully applied for fish remains from burbot Lota lota stomachs. Thus the technique could be a useful tool in monitoring biological invasions, especially by identifying specimens that could not be determined on the basis of morphological features. The results demonstrate that the PCR-RFLP method may in some cases be more reliable for species identification than a standard DNA sequencing.

First evidence for interspecific hybridization between invasive goby speciesNeogobius fluviatilisandNeogobius melanostomus(Teleostei: Gobiidae: Benthophilinae)

Two hybrids between the monkey goby Neogobius fluviatilis and the round goby Neogobius melanostomus from the Rhine River were identified by genotyping and morphological comparison. These are the first records of goby-hybrids outside the parent species' native ranges worldwide.