Figure 1
Figure 2
Figure 3
Percentage of taxa (%) in diatom assemblages at the sampling sites (relative abundance >5% at least at one site)_
| Taxa | S1 | S2 | S3 | S4 | S5 | S6 | S7 |
|---|---|---|---|---|---|---|---|
| Achnanthidium minutissimum (Kützing) Czarnecki | 1.0 | 0.5 | 16.9 | 16.4 | - | 0.9 | 0.9 |
| Amphora inariensis Krammer | - | - | 1.4 | 3.7 | - | - | 5.5 |
| Amphora pediculus (Kützing) Grunow | - | 0.5 | - | 1.5 | - | - | 9.1 |
| Cocconeis euglypta Ehrenberg | - | - | 0.7 | 5.2 | - | - | 2.7 |
| Cocconeis placentula var. placentula Ehrenberg | - | - | 0.7 | 18.7 | - | - | 0.9 |
| Cocconeis pseudolineata (Geitler) Lange-Bertalot | - | - | - | 5.2 | - | - | - |
| Encyonema ventricosum (C.Agardh) Grunow | - | - | 9.2 | - | - | - | - |
| Gyrosigma attenuatum (Kützing) Rabenhorst | 0.5 | 5.4 | - | - | - | - | - |
| Gyrosigma peisonis (Grunow) Hustedt | - | 10.3 | - | - | - | - | - |
| Halamphora coffeiformis (C.Agardh) Levkov | 1.5 | 7.6 | - | - | 10.2 | 15.1 | - |
| Karayevia clevei (Grunow) Round | - | - | 2.1 | 1.5 | - | - | 9.1 |
| Navicula cryptotenella Lange-Bertalot | - | - | 19.7 | - | - | - | - |
| Navicula erifuga Lange-Bertalot | 3.4 | 8.7 | - | - | - | - | - |
| Navicula flandriae Van de Vijver & A.Mertens | 28.2 | 6.0 | - | 0.8 | 75.2 | 74.9 | - |
| Navicula lacuum Lange-Bertalot, Hofmann, Werum & Van de Vijver | 0.5 | 8.2 | - | - | - | - | - |
| Navicula salinarum var. salinarum Grunow | - | 5.4 | - | - | 4.4 | 0.5 | - |
| Navicula supergregaria Rumrich & Lange-Bertalot | - | 6.0 | - | - | - | - | - |
| Nitzschia frustulum (Kützing) Grunow | 10.2 | 6.5 | - | - | 0.7 | - | - |
| Planothidium dubium (Grunow) Round & Bukhtiyarova | - | - | 0.7 | 0.8 | - | - | 5.5 |
| Sellaphora raederae (Lange-Bertalot) Wetzel | - | - | - | - | - | - | 6.4 |
| Seminavis sp. | 17.0 | 0.5 | - | - | - | - | - |
| Staurosirella martyi (Héribaud-Joseph) Morales & Manoylov | - | - | 5.6 | 3.0 | - | - | - |
| Staurosirella pinnata (Ehrenberg) Williams & Round | - | 0.5 | 2.8 | 1.5 | - | - | 33.6 |
Physical and chemical parameters of water, velocity, morphometric features of the studied rivers (sampling sites)_
| Parameter | Unit | S1 | S2 | S3 | S4 | S5 | S6 | S7 |
|---|---|---|---|---|---|---|---|---|
| Riverbed width | m | 7.10 | 4.30 | 4.07 | 3.60 | 2.70 | 8.10 | 7.00 |
| Riverbed depth | cm | 27.0 | 21.0 | 14.0 | 58.5 | 30.0 | 105.0 | 26.5 |
| Flow velocity | m s−1 | 0.055 | 0.451 | 0.105 | 0.722 | 0.023 | 0.170 | 0.143 |
| Temperature | °C | 19.3 | 19.4 | 10.4 | 11.8 | 17.5 | 16.5 | 11.0 |
| pH | 8.3 | 8.2 | 8.7 | 8.6 | 6.9 | 7.8 | 6.8 | |
| Conductivity | μS cm−1 | 14 630 | 35 700 | 280 | 320 | 400 | 9290 | 330 |
| Total dissolved solids | mg dm−3 | 7320 | 17 840 | 140 | 150 | 200 | 4640 | 160 |
| Chlorides | 6160 | 16 180 | 10 | 12 | 29 | 3960 | 14 | |
| Dissolved oxygen | 4.54 | 5.29 | 4.07 | 4.35 | 3.24 | 2.24 | 4.21 | |
| Sulfates | 660 | 480 | 40 | 41 | 42 | 212 | 12 | |
| Iron | 0.36 | 0.91 | 0.06 | 0.25 | 0.86 | 0.30 | 0.01 | |
| Ammonium | 0.58 | 1.83 | 0.00 | 0.12 | 0.38 | 1.03 | 0.01 | |
| Nitrites | 0.532 | 2.687 | 0.000 | 0.143 | 0.069 | 2.702 | 0.054 | |
| Nitrates | 0.00 | 0.00 | 2.66 | 6.65 | 1.33 | 21.26 | 11.08 | |
| Total nitrogen | 1.9 | 4.1 | 2.3 | 2.5 | 5.9 | 2.5 | 4.1 | |
| Phosphates | 0.06 | 0.06 | 0.01 | 0.04 | 0.25 | 0.44 | 0.11 | |
| Total phosphorus | 0.210 | 0.240 | 0.130 | 0.100 | 0.065 | 0.380 | < 0.050 | |
| Biochemical Oxygen Demand (BOD) | 7 | 23 | < 3 | < 3 | < 3 | 4 | < 3 | |
| Total Organic Carbon (TOC) | 2.5 | 3.5 | < 2.0 | < 2.0 | 9.8 | 8.7 | < 2.0 | |
| Calcium | 412 | 696 | 57 | 60 | 70 | 190 | 78 | |
| Magnesium | 75.57 | 476.64 | 0.73 | 0.12 | 35.36 | 91.25 | 19.56 | |
| Total hardness | mg CaCO3 dm−3 | 1340 | 3700 | 145 | 150 | 320 | 850 | 275 |
| Alkalinity | 360 | 280 | 95 | 130 | 150 | 235 | 150 |
Number of diatom taxa, values of the diatom index (IO) for the studied rivers (sampling sites)
| Characteristic | the Bolina River, upper reaches | the Bolina River, lower reaches | the Centuria River, upper reaches | the Centuria River, lower reaches | the Mitręga River, lower reaches | the Mleczna River, lower reaches | the Wiercica River, upper reaches |
|---|---|---|---|---|---|---|---|
| Number of taxa | 39 | 45 | 43 | 48 | 15 | 19 | 24 |
| Diatom index (IO) | 0.254 | 0.294 | 0.582 | 0.557 | 0.285 | 0.236 | 0.632 |
General characteristics of the studied rivers (sampling sites)
| Geographic coordinates/Characteristic features | the Bolina River, upper reaches | the Bolina River, lower reaches | the Centuria River, upper reaches | the Centuria River, lower reaches | the Mitręga River, lower reaches | the Mleczna River, lower reaches | the Wiercica River, upper reaches |
|---|---|---|---|---|---|---|---|
| Coordinate N | 50°13′47.6″ | 50°14′44.5″ | 50°24′52.7″ | 50°21′55.2″ | 50°26′04.2″ | 50°07′01.1″ | 50°41′18.0″ |
| Coordinate E | 19°05′08.5″ | 19°06′04.7″ | 19°29′11.4″ | 19°29′40.9″ | 19°17′57.4″ | 19°04′29.2″ | 19°24′42.0″ |
| Altitude (m a.s.l.) | 262 | 257 | 343 | 311 | 300 | 236 | 309 |
| Abiotic type | (type 5) mid-altitude siliceous streams with a fine particulate substrate | (type 6) mid-altitude calcareous streams with a fine particulate substrate on loess | (type 17) lowland sandy streams | ||||