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All of the non-indigenous amphipods occurring in the main course of the middle Danube are of Ponto-Caspian origin. Ponto-Caspian amphipod species in the main course of the Slovak section of Danube include
Dikerogammarus haemobaphes (Eichwald, 1842),
D. bispinosus Martynov, 1925,
D. villosus (Sowinskij, 1849),
Echinogammarus ischnus (Stebbing, 1898),
E. trichiatus (Martynov, 1932),
Obesogammarus obesus (Sars, 1894),
Corophium curvispinum Sars, 1895),
C. sowinskyi (Martynov, 1924) and
C. robustum (Sars, 1895).
Echinogammarus trichiatus (Martynov, 1932) recorded in 2007 near Bratislava was until now the newest element of this water region (Borza 2009). Further study of
Borza et al. (2010a) and
Borza (2011) indicated the possible occurrence of another Ponto-Caspian species in the Slovak section of Danube, the
C. robustum recording it on the Hungarian side of the river.
Corophium robustum was found for the first time for Hungary in 2007 (occurring at one site) and then later in 2009 (found at several sites) (Borza et al. 2010b and
Borza 2011). Despite, the species was overlooked in middle section of Danube River in “Joint Danube Survey 2” (Borza et al. 2011). Until now the species was found occurring only on the right side of the river from Nyergesújfalu (rkm 1843) to Nagymaros (rkm 1694) showing strong dominance (618 individuals of
C. robustum in contrast to six individuals of
C. sowinskyi and three records of
C. curvispinum at Komárom site) over other species of the genus (Borza 2011). The species is known to be present in the Main River, Germany, where it was discovered in 2002 (Bernerth & Stein 2003). Few years later the species occurred in the Rhine River at harbour in Karlsruhe and Mannheim (Bernauer & Jansen 2006). In 2007
C. robustum was recorded in the upper Danube at the Geisling power plant, Germany and at Greifenstein and Klosterneuburg, Austria (Borza et al. 2010a). Further spreading of this species is also recorded in the Dnieper River, Belorussia (Semenchenko et al. 2009).
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Material was sampled by kick and sweep method in littoral zone of the Danube River at approximately depth of 0.5 m. Samples were taken from eighteen sites through the whole Slovak section of Danube River (main course) during the years 2009 – 2011, of which the specimen occurred at four. Macrophotography was done by camera Canon EOS 5D equipped by Canon macro photo lens MP-E 65 mm. Images were stacked by the software Combine ZP to final image with higher focus depth (fig. 1). Specimens were identified in Zeiss stereomicroscope Stemi DV4 and microscope Zeiss Axioskop 40 using publications of
Cărăuşu (1943), Jażdżewski & Konopacka (1996) and
Borza et al. (2010). Morphological detail of the II antenna of the species is shown in fig. 2. Material was fixed in 96% of ethanol and is deposited at the Department of Zoology, Comenius University in Bratislava, Slovakia.
Sampling sites
Veľkolélsky ostrov
Samples were taken during year 2011. Sampling site is situated at the bank of the Veľkolélsky ostrov Island in the Danube River main channel (rkm 1781,
47°44’58.78”N 17°57’1.08”E). The bottom at sampling site is formed by sand and gravel with groups of stones. The main channel in this section keeps natural character of the bank with moderate slope of ripal zone.
Mužlianska Sihoť
Site is situated near the arrow weir between river bank and the island (rkm 1734,
47°46’6.63”N 18°32’18.82”E). The weir is submerged during high water levels but emerged during autumnal low discharges of river. Bottom deposits are formed by soft gravel and sand, influenced by higher current velocity.
The main channel exhibit moderate slope of ripal zone, however the uniformity of the main channel bottom is disturbed by the weir what results into higher diversity of habitats in the area.
Bratislava – „Pri kameňolome“ site, the Danube River
The specimen was found near the stone quarry above the Bratislava in the littoral zone of the Danube River at the river km 1878 (48°09’22.72”N 17°00’33.61”E) on 23. 5. 2012. The habitat was made of rip-rap and gravel.
Inlet of the Hron River to Danube
Second locality of occurrence was near by the inlet of the Hron River at the Danube river km 1716, near the village of
Kamenica nad Hronom (47°48’55.56”N 18°44’25.36”E), sampled 10. 11. 2011. The habitat of the Danube River at this locality was made of gravel and mud.
Identification of specimens was done according to
Sars 1894,
Cărăuşu 1943 and
Borza et al. 2010a. Taxonomy and nomenclature of the
Corophium genus was adopted according to database of Fauna Europaea (Boxhall 2012).
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Corophium sowinskyi Martynov, 1924 (Crustacea, Amphipoda, Corophiidae).
Bollettino del Museo Civico di Storia Naturale di Verona, 20: 487-501.
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