Figure 1
Figure 2
Figure 2
Year of sampling, depth, substrate type, dissolved oxygen and presence of macrophytes
| Crt. No. | Sites | Year of sampling | Depth (m) | Type of substrate | Dissolved oxygen mg/L | Macrophytes presence (+/-) | |
|---|---|---|---|---|---|---|---|
| Mean values/area | Value/site | ||||||
| Corabia area | 8.58 | ||||||
| 1. | km 626 | 2019 | 3.0 | sand | 8.90 | - | |
| 2. | km 626.5 | 2020 | 7.3 | gravelly sand | 8.10 | - | |
| 3. | km 627.5 | 2020 | 5.0 | sand | 8.81 | - | |
| 4. | km 629 | 2019 | 9.2 | gravelly sand | 8.82 | - | |
| 5. | km 630 | 2019 | 8.2 | gravelly sand | 8.04 | + | |
| 2020 | 8.67 | ||||||
| 6. | km 631 | 2019 | 5.3 | sand | 8.77 | - | |
| Bechet area | 8.77 | ||||||
| 7. | km 674 | 2019 | 3.3 | sand | 8.75 | - | |
| 8. | km 674.5 | 2019 | 3.2 | sand | 8.75 | + | |
| 9. | km 675 | 2019 | 4.0 | sand | 8.67 | - | |
| 10. | km 675.5 | 2019 | 6.3 | sand | 8.67 | + | |
| 11. | km 676 | 2019 | 3.7 | gravelly sand | 9.31 | + | |
| 2020 | 8.10 | ||||||
| 12. | km 676.5 | 2020 | 3.0 | sand | 8.15 | - | |
| 13. | km 678 | 2019 | 5.9 | sand | 9.78 | + | |
| Pisculeţ area | 8.85 | ||||||
| 14. | km 760 | 2019 | 3.9 | sand | 9.36 | - | |
| 15. | km 761 | 2019 | 4.2 | sand | 9.61 | + | |
| 16. | km 762 | 2019 | 5.0 | sand | 8.95 | + | |
| 2020 | 8.99 | ||||||
| 17. | km 762.5 | 2019 | 4.8 | gravelly sand | 8.96 | - | |
| 18. | km 764 | 2019 | 3.5 | sand | 8.55 | + | |
| 19. | km 764.5 | 2019 | 4.9 | sand | 8.55 | + | |
| 20. | km 765 | 2019 | 2.8 | gravelly sand | 8.38 | + | |
| 2020 | 8.31 | ||||||
| Cetate area | 7.80 | ||||||
| 21. | km 806 | 2019 | 3.8 | gravelly sand | 8.13 | - | |
| 22. | km 808 | 2019 | 5.0 | sand | 7.25 | - | |
| 23. | km 811 | 2019 | 7.8 | gravelly sand | 8.02 | - | |
| Sulina area | 8.25 | ||||||
| 24. | Old Danube meander | 2019 | 5.0 | sandy mud | 7.04 | - | |
| 25. | NM 24(a) Sulina branch | 2019 | 16.5 | sand | 7.93 | - | |
| 26. | NM 16 Sulina branch | 2019 | 5.2 | muddy sandy gravel | 7.90 | - | |
| 27. | NM 8(a) Sulina branch | 2019 | 14.4 | sandy mud | 7.95 | - | |
| 28. | NM 2 Sulina branch | 2019 | 17.5 | gravelly mud | 7.96 | - | |
| 29. | NM 33 Sulina branch | 2019 | 12.5 | gravelly mud | 9.38 | - | |
| 30. | NM 24(b) Sulina branch | 2019 | 12.5 | sand | 9.01 | - | |
| 31. | NM 14(b) Sulina branch | 2019 | 13.5 | sandy mud | 9.55 | - | |
| 32. | NM 8(b) Sulina branch (Meander) | 2019 | 4.3 | sandy mud | 9.07 | - | |
| 33. | NM 14(c) Sulina branch (Crisan) | 2019 | 11.5 | sand | 7.95 | - | |
| 34. | NM 14(a) Sulina branch (Crisan) | 2019 | 10.7 | gravelly mud | 7.95 | - | |
| 35. | NM 21 Sulina channel | 2019 | 6.5 | sandy mud | 7.97 | - | |
| 36. | Km 108(a) Ceatal Sf. Gheorghe | 2019 | 6.4 | sandy mud | 7.97 | - | |
| 37. | Km 108(b) Ceatal Sf. Gheorghe | 2019 | 6.4 | gravelly mud | 7.97 | - | |
Sampling locations in the Lower Danube and density of larvae
| Crt. No. | Sites | Coordinates | Number of individuals/m2 | |||||||
|---|---|---|---|---|---|---|---|---|---|---|
| Lat. (α) | Long. (λ) | G.f. | H.f. | E.v. | A.e. | H.b. | T.b. | S.m. | ||
| 1. | * km 811 | 44°4’53.2” | 23°1’48.8” | 0 | 0 | 7.4 | 0 | 0 | ||
| 2. | ** km 808 | 44°3’49.7” | 23°3’7.4” | 0 | 0 | 0 | 0 | 50.4 | 0 | 0 |
| 3. | ** km 806 | 44°2’55.3” | 23°2’14.5” | 0 | 0 | 0 | 0 | 226.8 | 0 | 0 |
| 4. | ** km 765 | 43°48’18.2” | 22°57’34.3” | 0 | 0 | 0 | 0 | 403.2 | 0 | 0 |
| 5. | 0 | 0 | 0 | 0 | 0 | 25.2 | 0 | |||
| 6. | ** km 764.5 | 43°48’36.8” | 22°58’12.0” | 0 | 0 | 0 | 0 | 0 | 1008 | 0 |
| 7. | ** km 764 | 43°48’5.7” | 22°58’35.5” | 0 | 0 | 0 | 0 | 25.2 | 25.2 | 0 |
| 8. | * km 762.5 | 43°48’37.7” | 22°59’52.7” | 7.4 | 0 | 0 | 0 | 162.8 | 0 | |
| 9. | * km 762 | 43°47’54.0” | 23°0’2.4” | 0 | 29.6 | 0 | 0 | 0 | 0 | 0 |
| 10. | 0 | 0 | 0 | 0 | 4388.2 | 7.4 | 0 | |||
| 11. | * km 761 | 43°48’14.3” | 23°0’54.4” | 0 | 0 | 0 | 0 | 0 | 7.4 | 0 |
| 12. | ** km 760 | 43°48’9.8” | 23°1’51.1” | 0 | 0 | 0 | 0 | 201.6 | 0 | 0 |
| 13. | * km 678 | 43°44’40,6” | 23°57’52.9” | 0 | 0 | 7.4 | 0 | 7.4 | 0 | 0 |
| 14. | * km 676.5 | 43°44’18.0” | 23°58’42.9” | 0 | 0 | 0 | 0 | 96.2 | 0 | 0 |
| 15. | * km 676 | 43°44’13.0” | 23°59’4.3” | 0 | 0 | 0 | 1813 | 0 | 0 | |
| 16. | 0 | 0 | 0 | 29.6 | 0 | 0 | 0 | |||
| 17. | * km 675.5 | 43°44’38,7” | 23°59’42,9” | 0 | 7.4 | 0 | 0 | 7.4 | 7.4 | 0 |
| 18. | * km 675 | 43°44’5.5” | 23°59’45.1” | 0 | 0 | 7.4 | 0 | 0 | 0 | 0 |
| 19. | * km 674.5 | 43°44’3.0” | 24°0’8.1” | 0 | 66.6 | 0 | 7.4 | 488.4 | 0 | 0 |
| 20. | ** km 674 | 43°43’52.9” | 24°0’27.3” | 0 | 0 | 0 | 0 | 25.2 | 0 | 0 |
| 21. | * km 631 | 43°46’8.3” | 24°29’58.8” | 0 | 96.2 | 0 | 0 | 0 | 0 | 0 |
| 22. | * km 630 | 43°45’32.0” | 24°30’49.5” | 0 | 429.2 | 14.8 | 0 | 0 | 0 | 0 |
| 23. | 0 | 0 | 0 | 0 | 1894.4 | 0 | 0 | |||
| 24. | * km 629 | 43°45’25.4” | 24°31’18.5” | 0 | 0 | 0 | 0 | 7.4 | 0 | 0 |
| 25. | ** km 627.5 | 43°45’17.2” | 24°32’34.2” | 0 | 25.2 | 0 | 0 | 252 | 0 | 0 |
| 26. | ** km 626.5 | 43°45’46.6” | 24°33’30.4” | 0 | 0 | 0 | 0 | 100.8 | 0 | 0 |
| 27. | * km 626 | 43°45’37.5” | 24°33’48.9” | 29.6 | 7.4 | 0 | 0 | 310.8 | 0 | 0 |
| 28. | * km 108(a) Ceatal Sf. Gheorghe | 45°11’04.9” | 28°53’26.7” | 0 | 0 | 0 | 0 | 214.6 | 0 | 0 |
| 29. | * km 108(b) Ceatal Sf. Ghoerghe | 45°11’04.39” | 28°53’26.7” | 0 | 0 | 0 | 0 | 7.4 | 0 | 0 |
| 30. | * NM 33 Sulina branch | 45°11’22.8” | 28°55’22.3” | 0 | 0 | 0 | 0 | 74 | 0 | 0 |
| 31. | * NM 24 (a) Sulina branch | 45°10’28.5” | 29°03’19.4” | 0 | 0 | 0 | 0 | 384.8 | 0 | 0 |
| 32. | * NM 24 (b) Sulina branch | 45°10’29.9” | 29°03’19.3” | 0 | 0 | 0 | 0 | 629 | 0 | 0 |
| 33. | * NM 21 Sulina channel | 45010’54.2” | 29°10’19.1” | 0 | 0 | 0 | 0 | 1420.8 | 0 | 0 |
| 34. | * NM 16 Sulina branch | 45°10’33.3” | 29°19’05.5” | 0 | 0 | 0 | 0 | 651.2 | 0 | 0 |
| 35. | * NM 14 (a) Sulina branch | 45°10’33.9” | 29°21’34.8” | 0 | 0 | 0 | 0 | 370 | 0 | 0 |
| 36. | * NM14 (b) Sulina branch | 45°10’32.4” | 29°21’17.0” | 0 | 0 | 0 | 0 | 1206.2 | 0 | 0 |
| 37. | * NM 14 (c) Sulina branch (Crisan) | 45°10’30.9” | 29°21’39.6” | 0 | 0 | 0 | 0 | 518 | 0 | 0 |
| 38. | * Old Danube (Meander) | 45°10’41.4” | 29°21’05.1” | 0 | 0 | 0 | 0 | 0 | 7.4 | 0 |
| 39. | * NM 8 (a) Sulina branch | 45°10’20.3” | 29°28’47.6” | 0 | 0 | 0 | 0 | 148 | 0 | 0 |
| 40. | * NM 8 (b) Sulina branch | 45°10’39.4” | 29°28’33.2” | 0 | 0 | 0 | 0 | 0 | 0 | 14.8 |
| 41. | * NM 2 Sulina branch | 45°09’39.6” | 29°36’31.6” | 0 | 0 | 0 | 0 | 296 | 0 | 0 |
Best match COI gene sequence of insect larvae species from the Danube River
| Insect species | Identity (%) | Cover (%) | GenBank reference |
|---|---|---|---|
| E. viridulum | 99.84 | 100.00 | MT298455.1 |
| G. flavipes | 99.36 | 98.00 | MT298633.1 |
| T. bicolor | 99.83 | 99.00 | KX143573.1 |
| H. bulgaromanorum | 100.00 | 98.00 | KX104210.1 |
| H. flava | 99.84 | 98.00 | KY262534.1 |
| A. ephemerella | 98.66 | 97.00 | LR135742.1 |
| S. morio | 98.41 | 97.00 | JX438311.1 |
Association of insect larvae with different types of substrate
| Insect species | Order | Type of substrate | ||||
|---|---|---|---|---|---|---|
| Sand | Gravelly sand | Muddy sandy gravel | Gravelly mud | Sandy mud | ||
| Erythromma viridulum | Odonata | + | + | - | - | - |
| Gomphus flavipes | + | + | - | - | - | |
| Triaenodes bicolor | + | + | - | - | + | |
| Hydropsyche bulgaromanorum | Trichoptera | + | + | + | + | + |
| Heptagenia flava | Ephemeroptera | + | + | - | - | - |
| Acentria ephemerella | Lepidoptera | + | + | - | - | - |
| Sialis morio | Megaloptera | - | - | - | - | + |