Figure 1
Figure 2
Figure 3
Figure 4
Figure 5
Mean values of abiotic parameters of water and bottom sediments of the studied lakes
| Parameter | Macrophyte-dominated lakes | Phytoplankton-dominated lake | |||||||
|---|---|---|---|---|---|---|---|---|---|
| shallower | deeper | ||||||||
| Zielone | Karaś | Piotrkowskie | Głuchowskie | Ząbrowo | Jeziorak∗ | Stęgwica | Kolmowo | Silm | |
| Secchi depth (m) | 2.2 | 2.1 | 2.1 | 2.0 | 1.7 | 0.8 | 0.7 | 1.0 | 1.4 |
| Water above the bottom | |||||||||
| Temperature (oC) | 13.5 | 13.4 | 14.0 | 12.6 | 12.3 | 12.1 | 11.2 | 12.3 | 13.4 |
| Oxygen concentration (mg dm-3) | 8.0 | 7.8 | 9.3 | 6.4 | 10.0 | 10.8 | 6.9 | 7.2 | 7.2 |
| pH | 7.5 | 7.9 | 8.0 | 8.6 | 8.3 | 8.7 | 7.2 | 8.5 | 8.0 |
| Conductivity (μS cm-1) | 100 | 496 | 253 | 577 | 428 | 309 | 199 | 428 | 425 |
| Bottom sediments | |||||||||
| E × D | 2.4 | 2.7 | 2.2 | 5.5 | 2.7 | 4.4 | 2.9 | 8.3 | 7.6 |
| Water content (%) | 97.3 | 94.6 | 96.6 | 93.3 | 95.8 | 96.1 | 95.5 | 94.7 | 97.4 |
| Organic matter (%) percentage of dry mass of sediments | 78.4 | 39.2 | 64.9 | 32.6 | 49.8 | 51.7 | 54.8 | 34.6 | 58.6 |
| Organic matter (mg) in milligrams of dry mass per unit of fresh sediment volume (10 cm3) | 170 | 217 | 226 | 242 | 215 | 136 | 252 | 189 | 159 |
| SOD sediment oxygen demand (mg O2 per 20 cm3 of fresh sediments per 1 h)) | 2.6 | 3.3 | 3.2 | 6.2 | 5.1 | 4.7 | 4.3 | 8.2 | 3.4 |
Percentage of sexually mature individuals of Potamothrix hammoniensis in the distinguished size classes
| Lakes | Macrophyte-dominated | Ph-D | Ph-S | Average | Average | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Class | Zielone | Ząbrowo | Karaś | Piotrkowskie | Głuchowskie | Kolmowo | Silm | Stęgwica | Jeziorak | M | Ph-D | Ph-S | |
| V | 0 | 0 | 0 | 0 | 20 | 1 | 0 | 1 | 12 | 2 | < 1 | 1 | 4 |
| VI | 3 | 18 | 0 | 0 | 67 | 10 | 24 | 7 | 19 | 10 | 7 | 15 | 10 |
| VII | 20 | 47 | 40 | 26 | 78 | 25 | 15 | 17 | 35 | 24 | 28 | 21 | 21 |
| VIII | 42 | 70 | 54 | 100 | 100 | 32 | 44 | 36 | 73 | 46 | 50 | 36 | 47 |
| IX | 62 | 85 | 83 | 100 | 100 | 75 | 92 | 84 | 82 | 80 | 75 | 82 | 83 |
| X | 85 | 100 | 100 | 100 | 80 | 100 | 67 | 100 | 90 | 94 | 92 | 80 | |
| XI | 100 | 100 | 100 | 50 | 80 | 100 | 100 | 87 | 100 | 71 | 100 | ||
| XII | 100 | 100 | 100 | ||||||||||
Basic characteristics of the studied lakes
| Parameter | Macrophyte-dominated lakes | Phytoplankton-dominated lakes | |||||||
|---|---|---|---|---|---|---|---|---|---|
| shallower | deeper | ||||||||
| Zielone | Karaś | Piotrkowskie | Głuchowskie | Ząbrowo | Jeziorak – Lake Jeziorak is the longest lake in Poland (length: 27.4 km, surface: 3230 ha). The study in this lake was carried out in a shallow bay part (its morphometry is provided in Table 1) located in the oldest southern part of the lake. | Stęgwica | Kolmowo | Silm | |
| Surface (ha) | 20.2 | 423.3 | 54.4 | 24.1 | 12.7 | 80.0 | 39.7 | 43.4 | 58.8 |
| Maximum length (m) | 1375 | 4100 | 1450 | 740 | 960 | 2800 | 1880 | 1050 | 1625 |
| Maximum width (m) | 240 | 2250 | 850 | 475 | 215 | 1000 | 290 | 550 | 800 |
| Maximum depth (m) | 2.4 | 2.8 | 2.5 | 4.5 | 1.6 | 2.0 | 1.4 | 5.7 | 3.8 |
| Mean depth (m) | 1.3 | 0.6 | 1.7 | 2.2 | 1.1 | 1.3 | 1.0 | 3.1 | 2.0 |
| Number of sampling locations | 6 | 2 | 2 | 2 | 2 | 7 | 7 | 4 | 3 |
| Depth at sampling locations (m) | 1.5–2.2 | 1.6 ; 2.0 | 1.5 ; 2.0 | 3.0 ; 4.0 | 1.2 ; 1.5 | 1.0–1.5 | 1.2–1.4 | 2.0–3.0 | 3.5 |
| Catchment F – forest, A – agricultural, M – marsh, T – affected by tourism | F | A/M | F | A | F/A | F/T | F | A | F |
| Wind exposure | low | high | medium | high | low | medium | medium | high | medium |
| Dominating elodeid species E.c. – Elodea canadensis, Ch.sp. – Chara sp., C.d. – Ceratophyllum demersum | E.c. | Ch.sp. | Ch.sp. | C.d. | C.d. | ||||
| Elodeid abundance the abundance of elodeids refers to their density in the central part of the lake, assessed arbitrarily on a scale from 1 to 10, where 1 denotes the complete absence of plants, and 10 means that the macrophytes overgrow the entire water volume | 5 | 7 | 8 | 8 | 9 | 1 | 1 | 1 | 1 |
Number of examined individuals of Potamothrix hammoniensis – the sum of all sampling sites and dates
| Lakes | Macrophyte-dominated | Ph-D | Ph-S | Sum | sum | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Class | Zielone | Ząbrowo | Karaś | Piotrkowskie | Głuchowskie | Kolmowo | Silm | Stęgwica | Jeziorak | M | Ph-D | Ph-S | |
| V | 163 | 18 | 31 | 33 | 5 | 68 | 11 | 270 | 95 | 694 | 250 | 79 | 365 |
| VI | 204 | 22 | 15 | 20 | 12 | 100 | 54 | 327 | 91 | 845 | 273 | 154 | 418 |
| VII | 161 | 17 | 15 | 19 | 18 | 57 | 34 | 230 | 69 | 620 | 230 | 91 | 299 |
| VIII | 109 | 20 | 13 | 1 | 6 | 37 | 18 | 92 | 37 | 333 | 149 | 55 | 129 |
| IX | 26 | 13 | 12 | 4 | 2 | 16 | 12 | 43 | 22 | 150 | 57 | 28 | 65 |
| X | 13 | 10 | 9 | 1 | 5 | 8 | 9 | 6 | 61 | 33 | 13 | 15 | |
| XI | 2 | 2 | 1 | 2 | 5 | 2 | 1 | 15 | 5 | 7 | 3 | ||
| XII | 1 | 1 | 1 | ||||||||||
| Sum | 678 | 102 | 96 | 78 | 43 | 286 | 142 | 973 | 321 | 2719 | 997 | 428 | 1294 |
Values of Pearson’s linear correlation coefficient (r) and the significance level (p) between the percentage of sexually mature individuals of Potamothrix hammoniensis and the environmental variables under study_ Statistically significant values are boldfaced
| Statistics | Near-bottom water | E × D | Bottom sediments | ||||||
|---|---|---|---|---|---|---|---|---|---|
| Temperature | Oxygen concentration | pH | Conductivity | WC | OC (%) | OC (mg) | SOD | ||
| r | −0.22 | 0.08 | 0.51 | 0.69 | 0.30 | −0.21 | −0.42 | −0.10 | 0.22 |
| p | 0.204 | 0.648 | 0.002 | < 0.000 | 0.080 | 0.226 | 0.012 | 0.568 | 0.204 |
j_ohs-2018-0017_tab_006
| class | width of the 8th segment (mm) |
|---|---|
| I | < 0.20 |
| II | 0.21–0.30 |
| III | 0.31–0.40 |
| IV | 0.41–0.50 |
| V | 0.51–0.60 |
| VI | 0.61–0.70 |
| VII | 0.71–0.80 |
| VIII | 0.81–0.90 |
| IX | 0.91–1.00 |
| X | 1.01–1.10 |
| XI | 1.11–1.20 |
| XII | 1.21–1.30 |