L. Forró szerk.: Miscellanea Zoologica Hungarica 7. 1992 (Budapest, 1992)

Forró, L.; Gulyás, P.: Eurytemora velox (Lilljeborg, 1853) (Copepoda, Calanoida) in the Szigetköz region of the Danube

Table 1 provides data about the chemical features of the localities where E. velox was found in this study. These sites are freshwater ones, various channels and ponds, where this species was always found in samples taken at the shoreline. The sample from the open water of the Öntési-tó did not have E. velox, while it was collected in the littoral zone and small nearby channels. làble 1. Chemical features of selected localities of E. velox (Legend: 1 = Zátonyi Duna, Doborgazsziget, at the Hostel, 07. 06. 1991; 3 = Zátonyi'Duna, Doborgaz-sziget, at the Hostel, 06. 09. 1991; 4 = Gazfûi Holt Duna, downstream section at the protecting dike, 07. 06. 1991; 5 = Szavai channel, at Patkánvosi pump station, 03. 06.1991; 7 = Ásványráró, Port, 06. 09. 1991) 0

2 (mg.dnr

3

) pH7.6 conductivity («S.cm"

1

) K

+ (g.m3

) Na

+ (g.m"

3

) Ca

2+ (g.m"

3

) Mg

2+ (g.nr

3

) C0

3

2- (g.nr

3

) HCO3- (g.nr

3

) CI" (g.m"

5

) S0

4

* (g.nr

3

) NH4-N (g.m"

3

) NO2-N (g.nr

3

) NO3-N (g.m"

3

) PO4-P (g.m"

3

) Chi a (mg.m"

3

) trophic level meso- meso- oligo- oligotrophic trophic meso- mesotrophic trophic 1 3 4 5 7 14.8 12.8 8.2 16.2 7.5 7.1 315 850 600 2.1 2.1 8.3 0.0 7.3 6.3 8.8 6.0 37.3 40.9 140.0 108.0 12.2 13.5 33.6 23.8 0.0 0.0 0.0 0.0 159.0 201.0 250.0 384.0 16.3 17.3 24.4 14.2 10.0 25.0. 260.0 54.0 <0.04 <0.04 <0.04 0.018 < 0.003 < 0.003 1.1 <0.2 <0.2 <0.02 <0.02 <0.02 14.4 12.4 7.1 9.4 Occurrence: E. velox usually occurs when temperature is above 10 °C, Lescher-Moutoué (1984) observed its presence between April and October, and its greatest abundance in summer. In temporary saline waters in the Camargue it appeared in spring and disappeared early summer, but occurred again in autumn (Champeau 1970). Siewerth (1926) found it in the warm period only. It is assumed that E. velox is able to produce resting eggs. Dumont & Gysels (1971) found E. velox at 11 sites, where 4-19 (mostly more than 10) Cladocera and Copepoda species co-occurred. In North-Germany, in brackish ponds quite few species have been found along with E. velox: D. magna at one site, while two copepods, Centropages hamatus and Mesochra lilljeborgi at another locality (Kukert 1984). In the Szigetköz area 6-17 Cladocera and Copepoda species were found in the samples with E. velox (Table 2).