Microcrustacean (Cladocera, Copepoda) source-sink dynamics in a lowland river ecosystem with a dam reservoir

Figure 1

Figure 2

Figure 3

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

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