Influence of the twilight period and different sampling methods on catch of Gobiids (Gobiidae) at four locations in the inshore parts of the Danube River (original) (raw)
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Journal of Applied Ichthyology, 2009
In the years 2000–2001, specimens of two Ponto-Caspian gobiids (racer goby Neogobius gymnotrachelus and monkey goby Apollonia fluviatilis) were recorded for the first time in the lower Vistula River, which is a part of the central inland corridor used by Ponto-Caspian species to migrate in Europe. In 2004, seine net surveys were made in the river course to examine relative abundance of the non-indigenous gobiids in the local small-fish community. Altogether 4420 specimens with total lengths ranging from 10 to 340 mm (mostly <100 mm) belonging to 18 species were recorded in 70 hauls. Monkey goby was one of the subdominant species (18.1% of total number of fish captured; 64.3% frequency of occurrence in hauls) together with bleak Alburnus alburnus (21.0, 54.3), roach Rutilus rutilus (18.2, 67.1) and three-spined stickleback Gasterosteus aculaetus (17.3, 37.1). Racer goby was less abundant but quite common (2.5, 32.9), similar to common bream/white bream Abramis brama/Blicca bjoerkn...
Invasive Ponto-Caspian (P-C1) 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 Basinwere 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.
New record of Neogobius fluviatilis (Pallas, 1814) (Gobiidae) in the Danube river basin (Serbia)
Archives of Biological Sciences, 2013
Recently, the growing colonization of allochthonous organisms in the Serbian section of the Danube River and interconnected ecosystems was observed. Hydro-morphological changes, such as regulations of the watercourse, have made this sector suitable for bio-invasions. Two specimens of Neogobius fluviatilis (Pallas, 1814) (Piscea: Gobidae) were collected on 10 August 2012 from the Zapadna Morava River, below the first dam on the river course. This is the first record of the sand goby in the watercourse in the central part of Serbia, as a tributary of the Danube River. Our findings show that the sand goby has thus far reached not only the main course of the Danube River but its tributary as well. This freshwater fish was observed for the first time in the Serbian part of the Danube River in 1986 in Begej locality (1.276 km). There are five Ponto-Caspian goby species in the waters of Serbia.
Aquatic Invasions, 2008
Dietary breadth and diet overlap were examined in two native fish species (Eurasian perch Perca fluviatilis, Balon's ruffe Gymnocephalus baloni) and two invading species (round goby Neogobius melanostomus, bighead goby Neogobius kessleri) in the Middle Danube (Slovakia) at dawn and dusk over two consecutive 24-h periods in late summer 2004. Dietary breadth was narrow in all species/age classes except perch of ages 4 and 5. Dietary overlap between native fishes and the invading gobies was very high, except for age 3 perch. This high overlap was due to a preference, high in some cases, for gammarids. Our preliminary results suggest the potential for competition between the invading and native fishes, which requires further study.
International Review of Hydrobiology, 2007
Since 1997, three new Neogobius species (Neogobius kessleri, N. fluviatilis and N. melanostomus) have been regularly recorded in the Slovak part of the Danube River, formerly inhabited only by one native gobiid species (Proterorhinus marmoratus). The study of their food habits proved that the amphipod Corophium curvispinum, chironomid larvae and pupae, caddis fly larvae (Hydropsyche sp.) and mayfly nymphs (Ephoron virgo, Potamanthus luteus) were the most important food items contributing to the similarity of the diets of the gobiid species. Fish (0+ Zingel zingel and Sander lucioperca) appeared in the diet of N. kessleri only.
The first report of round goby, Neogobius melanostomus (Pisces, Gobiidae) in the waters of Slovakia
2004
After Neogobius kessleri, Neogobius gymnotrachelus, and Neogobius fluviatilis, Neogobius melanostomus is the fourth species of Gobiidae to find its way up the River Danube to Slovakia, occurring in our samples near Štúrovo (river km 1720) and in the River Hron (river km 0.82). The fish (male, females, juvenile) were captured along weakly sloped sandy riverbanks with large stones. The mensural and meristic characters of the specimens were similar to those reported elsewhere for the species.
Cybium: international journal of ichthyology
Prior to the present study, the gobiid biodiversity of the Adriatic Sea varied significantly between the north ern (98% of the known Adriatic gobiid biodiversity) and central (89%) as compared to the southern Adriatic Sea (39%). Thirteen species are newly recorded for the southern Adriatic area and one for the central Adriatic. The relatively small col lecting effort in this survey produced a large increase in the known gobiid biodiversity, which suggests that the low number of known Adriatic gobiid species in the southern Adriatic mirrors only sampling intensity and not the real species richness of the area. The gobiid zoogeography in the Adriatic is compared with that of the Mediterranean.
Distribution of Gobiid Species (Gobiidae, Pisces) in the Yantra River (Danube Basin, Bulgaria)
2008
Recently, a rapid spread of some species of family Gobiidae upstream the Danube River and its tributaries has been observed. The distribution of gobiid species in the Yantra River (Danube tributary in Bulgaria) was studied. Four gobiid species (out of six species occurring in the Danube) were recorded: Neogobius fluviatilis, N. gymnotrachelus, N. melanostomus, and Proterorhinus marmoratus. Most frequently occurred
Journal of Great Lakes Research, 2001
The round goby Neogobius melanostomus was the last Ponto-Caspian goby species to enter in the Danube River bordered by Serbia and Yugoslavia. There are five Ponto-Caspian goby species in the waters of Serbia including the sand goby Neogobius fluviatilis, the round goby Neogobius melanostomus, the racer goby Neogobius gymnotrachelus, the bighead goby Neogobius kessleri, and the tubenose goby Proterorhinus marmoratus. The sand, bighead, and tubenose gobies occur along the Yugoslav Danube and in the lower reach of the Danube's tributaries; the racer goby is found both upstream and downstream of the Djerdap II dam; and, the round goby has been collected only downstream of the Djerdap II dam. Investigations on the continuous morphological characters of the round goby revealed neither sexual dimorphism, nor significant differences in adult size-classes, although some suggestions of sexual dimorphism were found in cranial skeletal analyses. Analysis of external continuous characters revealed a west-east cline along the distribution range of the round goby in the Black Sea basin. Molluscivory for the round goby was corroborated along the Danube. Standard length of each age class for the round goby in the Danube was less than populations in the Caspian and Azov seas.