Figure 1
Map of the study sites with the location of the sampling stations; square: Siemianówka Reservoir (SR) and Narew River (km distance from the dam:10, 25, 55, 90, 120, 130); circle: oxbow lakes (1 - 40)
Table 1
Characteristics of the study stations in the Siemianówka Reservoir (SR) along the Narew River (distance from the dam: 10, 25, 55, 90, 120, 130 km) and in oxbow lakes (according to Grabowska et al. 2013)
| Station name | Distance from the dam (km) | Character of the river | Velocity (m s-1) | Average discharge (m3 s-1) | Number of samples |
|---|---|---|---|---|---|
| SR | 0 | Reservoir | - | 4.1 | 19 |
| 10 | 9.1 | Meandering | 0.52-0.64 | 4.6 | 19 |
| 25 | 25.5 | Meandering | 0.44-0.51 | 8.2 | 19 |
| 55 | 56.0 | Meandering | 0.35-0.42 | 13.2 | 19 |
| 90 | 88.2 | Meandering | 0.65-0.80 | 15.1 | 19 |
| 120 | 118.0 | Anastomosing | 0.40-0.60 | 16.0 | 19 |
| 130 | 130.0 | Anastomosing | 0.62-0.75 | 18.2 | 9 |
| OXBOW LAKES | |||||
| 1-6 | 0.3-90 | Meandering | 17 | ||
| 7-32 | 91-130 | Anastomosing | 72 | ||
| 33-40 | 131-180 | Regulated | 12 | ||
Table 2
Average ± SD population density and frequency of planktonic species in the Siemianówka Reservoir (SR), along the Narew River as in Table 1 and in oxbow lakes. Potential for colonization of oxbow lakes by the planktonic species leaving the Siemianówka Reservoir was expressed by the habitat preference index (HPI).
| Diaphanosoma brachyurum | Daphnia cucullata | Chydorus sphaericus | Mesocyclops leuckarti | ||
|---|---|---|---|---|---|
| population density (ind. l-1) | SR | 12 ± 24 | 17 ± 11 | 51 ± 77 | 41 ± 29 |
| 10 | 1.4 ± 2 | 15 ± 14 | 51 ± 46 | 55 ± 106 | |
| 25 | 0.3 ± 0.7 | 3.1 ± 3.6 | 5.5 ± 6.4 | 12.4 ± 35 | |
| 55 | 0.1 ± 0.3 | 2.5 ± 5.4 | 7.4 ± 20 | 7 ± 16.7 | |
| 90 | 0.01 ± 0.04 | 0.4 ± 1.2 | 11.2 ± 42 | 1.3 ± 2.7 | |
| 110 | 0.03 ± 0.1 | 0.3 ± 0.5 | 4.3 ± 15 | 1.4 ± 4.8 | |
| 130 | 0.4 ± 1 | 0.2 ± 0.3 | 1.2 ± 2.1 | 0.1 ± 0.2 | |
| oxbow lakes | 0.7 ± 0.9 | 1.6 ± 4.6 | 8.3 ± 23.5 | 3.3 ± 7 | |
| frequency | SR | 79% | 100% | 100% | 100% |
| 10 | 44% | 100% | 94% | 100% | |
| 25 | 16% | 58% | 84% | 84% | |
| 55 | 11% | 37% | 79% | 68% | |
| 90 | 5% | 11% | 63% | 58% | |
| 110 | 5% | 21% | 47% | 37% | |
| 130 | 11% | 33% | 33% | 22% | |
| oxbow lakes | 4% | 17% | 67% | 51% | |
| HPI | -0.99 | -0.90 | -0.63 | -0.77 | |
Figure 2
Similarity between crustacean communities (%) in the Narew River (grey) and oxbow lakes (black) to crustacean communities in the Siemianówka Reservoir
Figure 3
Internal preference mapping of the hydrological connectivity and the cover of macrophytes on the crustacean communities (dot – littoral species; square – planktonic species with eurytopic Chydorus sphaericus and Mesocyclops leuckarti; triangle – benthic species)