1. ICES Annual Science Conference Baltic Committee meeting Maastricht, September 18-23, 2006
Modern development of barrier salinity zones relativity and plurality conception
N.V. Aladin, I.S. Plotnikov, M.B. Dianov Zoological Institute of Russian Academy of Sciences, St.Petersburg

2. Water salinity is one of major environmental factors influencing hydrobionts. Ascertainment of specificity of the attitude of aquatic animals and plants to this factor is important to understand both autoecological and synecologilal rules.
Conception of relativity and plurality of water barrier salinity zones was formulated more than 20 years before in the frames of V.V. Khlebovich’s school of thought (Aladin, 1986). Its main theses were published in the Journal of General Biology (Aladin, 1988).
Two main theses were stated:
Zones of barrier salinities are relative, on the one hand, to the degree of perfection of hydrobionts osmoregulatory capacities and, on the other hand, to the water chemical composition.
There are several zones of barrier salinities and they are unequal by their importance.

3. Zones of barrier salinities and tolerance ranges of hydrobionts from marine and continental waters : horizontal axis – salinity, ‰; over horizontal axis are given salinity tolerance ranges of hydrobionts from marine waters; below horizontal axis – for those from continental waters.
Osmoconformers: 1 – I, 2 – II, 3 – III;
confohyperosmotics: 4 – I, 5 – II; 6 – hyperosmotics I, 7 –hyperosmotics II or secondary confohyperosmotics;
amphiosmotics: 8 – I, 9 – II, 10 – III, 11 – IV; 12 – hypoosmotics;
Barrier salinities of marine waters: I M – first, 5 –8‰, II M – second, 16–20‰, III M – third, 26–30‰, IV M – fourth, 36–40‰, V M – fifth, 50–55‰;
barrier salinities of continental waters : I c – first, 5–20‰, II c – second, 50–60‰, III c – third, 100–300‰ and more;
A – marine brackish waters; A* – before “critical salinity” 5–8‰, A** – after “critical salinity” 5–8‰, B – typical marine waters, C – marine hyperhaline waters, D – fresh waters, E – continental brackish waters, E*– in the “critical salinity” zone 5–20‰, E**– after the the “critical salinity” zone, F – continental hyperhaline waters.
Summarized from: Journal of General Biology, 1988, vol. 67(7):

4. All the hydrosphere of our planet could be conditionally divided into freshwater, brackish water, marine and hyperhaline zones.
Marine zone occupies about 95% of the hydrosphere surface.
Freshwater zone occupies about 3%.
Brackish water and hyperhaline zones occupy about 0.5% each.
Between these four basic zones there are transitional ones occupying less than 0.5% each.
Approximate boundaries and corresponding barrier salinities are found for all of these basic and transitional zones of the hydrosphere are defined.

5. Zones Ocean Caspian Aral 0-2 ‰ 0-2.5 ‰ 0-3 ‰ 2-5 ‰ 2.5-7 ‰ 3-8 ‰ 5-8 ‰
Following main principles of conception of relativity and plurality of salinity barrier zones (Aladin, 1986, 1988; Aladin, Plotnikov, 2007) the following salinity zones were suggested for oceanic, Caspian and Aral waters.
Zones
Ocean
Caspian
Aral
Basic freshwater
0-2 ‰
0-2.5 ‰
0-3 ‰
Transitional
freshwater-brackishwater
2-5 ‰
2.5-7 ‰
3-8 ‰
Basic brackishwater
5-8 ‰
7-11 ‰
8-13 ‰
brackishwater-marine
8-26 ‰
11-28 ‰
13-29 ‰
Basic marine
26-40 ‰
28-41 ‰
29-42 ‰
marine-hyperhaline
40-50 ‰ ‰
42-51 ‰
Basic hyperhaline
> 50 ‰
> 50.5 ‰
> 51 ‰

6. Following the main principles of conception of relativity and plurality of salinity barrier zones (Aladin, 1986, 1988; Aladin, Plotnikov, 2007) the following salinity zones were suggested for oceanic, Caspian and Aral waters.

7. Revealing barrier salinity zones in the hydrosphere supposes studying osmoregulatory capacities of hydrobionts first of all. It is to reveal types of osmotic relations of internal media with the environment, to find experimentally limits of salinity tolerant ranges, to analyze data on salinity boundaries of hydrobionts distribution in the nature.

8. Classification of osmoconformers and osmoregulators
Aquatic organisms
Osmoconformers
Osmoregulators
Osmoconformers I
Confohyperosmotics
Hypoosmotics
Osmoconformers II
Amphyosmotics
Hyperosmotics
Osmoconformers III
Amphyosmotics I
Hyperosmotics I
Confohyperosmotics I
Amphyosmotics II
Hyperosmotics II
Confohyperosmotics II
Amphyosmotics III
Amphyosmotics IV

9. General table of osmoconformers and osmoregulators
Confohyperosmotics
Hyperosmotics
Amphyosmotics
Hypoosmotics I II
III IV
Osmoconformers – majority of recent primary marine hydrobionts: Coeletnterata, Vermes, Mollusca, Arthropoda, Echinodermata, etc.
Confohyperosmotics – majority of recent widely euryhaline primary marine hydrobionts: Polychaeta, Gastropoda, Crustacea, etc.
Hyperosmotics – majority of recent freshwater hydrobionts: Oligochaeta, Rotatoria, Mollusca, Crustacea, Insecta, freshwater Pisces, etc.
Amphyosmotics – some Crustacea, some Insecta, anadrom Pisces.
Hypoosmotics – some secondary marine Crustacea, majority of recent secondary marine Pisces.

10. Evolution of all known types of osmoregulation
A0 – Hypothetic ancestral osmoconformer
A1  – Stenohaline marine hydrobionts (osmoconformers I)
A2  – Marine hydrobionts (osmoconformers II)
A3  – Euryhaline marine hydrobionts (osmoconformers III)
B1 – Widely euryhaline marine hydrobionts (confohyperosmotics I)
B2  – Brackish water hydrobionts of marine origin (confohyperosmotics II)
C1  – Freshwater hydrobionts (hyperosmotics I)
C2  – Brackish water hydrobionts of freshwater origin (hyperosmotics II or secondary confohyperosmotics)
D1  – Some Caspian brackish water hydrobionts (amphiosmotics I)
D2  – Some euryhaline Australian hydrobionts of freshwater origin (amphiosmotics II)
D3  – Euryhaline hydrobionts of freshwater origin (amphiosmotics III)
D4  – Widely euryhaline hydrobionts of freshwater origin (amphiosmotics IV)
E  – Euryhaline marine hydrobionts of freshwater origin (hypoosmotics) 

11. Different levels of Ostracoda and Branchiopoda occurrence in marine and continental waters (by: Aladin, 1986)
Levels of occurrence
Marine waters
Continental waters
Typical marine waters
Brackish waters
Hyperhaline waters
Fresh waters
Mass
A1, A2, E
A3, B1, B2, E
B1, E C1
C2, D1, D3 D4
Rare
A3, B1, B2 -
C2, D1, D3, D4
Bringing / invasion
D3, D4
C1, C2, D1, D3, D4
B1, B2

12. The position and width of barrier salinities ranges cannot depend on water physicochemical properties only. The values of barrier salinities can change following evolution of salinity adaptations and osmoregulation capacities of aquatic plants and animals.

13. α-, β- and g- horohalinicums in the waters classified by salinity (by: Aladin, 1986, 1988; Khlebovich, 1989 )

14. Special attention needs to be given on comparative analysis of oceanic (thalassic) zones of hydrosphere and those continental (athalassic).

15. Critical salinity shift to higher concentrations in water of Caspian and Aral seas as compared with oceanic water (by: Aladin, 1986, 1989)

16. We shall review some water bodies where we had our studies.

17. Aral Sea before 1960
 - Freshwater ecosystems
 - Transitional freshwater-brackishwater ecosystems
 - Brackishwater ecosystems
 - Transitional brackishwater-marine ecosystems

18. Aral Sea in 1989
 - Freshwater ecosystems
 - Transitional freshwater-brackishwater ecosystems
 - Brackishwater ecosystems
 - Transitional brackishwater-marine ecosystems
 - Marine ecosystems

19. Aral Sea in 2006
 - Freshwater ecosystems
 - Transitional freshwater-brackishwater ecosystems
 - Brackishwater ecosystems
 - Transitional brackishwater-marine ecosystems
 - Hyperhaline ecosystems

20. Caspian Sea
 - Freshwater ecosystems
 - Transitional freshwater-brackishwater ecosystems
 - Brackishwater ecosystems
 - Transitional brackishwater-marine ecosystems
 - Marine ecosystems
 - Transitional marine-hyperhaline ecosystems
 - Hyperhaline ecosystems

21. Sea of Azov  - Freshwater ecosystems
 - Transitional freshwater-brackishwater ecosystems
 - Brackishwater ecosystems
 - Transitional brackishwater-marine ecosystems
 - Marine ecosystems
 - Transitional marine-hyperhaline ecosystems
 - Hyperhaline ecosystems
Sea of Azov

22. Black Sea
 - Freshwater ecosystems
 - Transitional freshwater-brackishwater ecosystems
 - Brackishwater ecosystems
 - Transitional brackishwater-marine ecosystems

23.  - Freshwater ecosystems
 - Transitional freshwater-brackishwater ecosystems
 - Brackishwater ecosystems
 - Transitional brackishwater-marine ecosystems
 - Marine ecosystems
Baltic Sea

24. White Sea  - Freshwater ecosystems
 - Transitional freshwater-brackishwater ecosystems
 - Brackishwater ecosystems
 - Transitional brackishwater-marine ecosystems
 - Marine ecosystems
White Sea

25. Barentz Sea  - Freshwater ecosystems
 - Transitional freshwater-brackishwater ecosystems
 - Brackishwater ecosystems
 - Transitional brackishwater-marine ecosystems
 - Marine ecosystems
Barentz Sea

26. Sea of Japan
 - Marine ecosystems

27. Ladoga Lake
 - Freshwater ecosystems

28. Baltic Sea
Sea of Azov
Aral Sea prior 1960
Aral Sea in 2006
Caspian Sea

29. Area of different salinity zones in different brackish water seas and lakes

30. Percentage of water areas of different salinity zones in different brackish water seas and lakes
Aral Sea
Caspian
Black
Sea
Baltic
Zones
(in 2006)
(prior 1960)
of Azov
Basic freshwater
0.01
0.93
5.02
0.25
2.26
5.63
Transitional freshwater-brackishwater
0.04
2.58
6.52
0.03
3.33
14.89
Basic brackishwater
0.23
88.65
13.42
0.02
7.87
61.54
Transitional brackishwater-marine
20.71
7.84
70.87
99.70
82.90
4.10
Basic marine
0.00
1.15
13.84
Transitional marine-hyperhaline
0.53
Basic hyperhaline
79.01
4.11
1.96
At present Baltic Sea is the only sea where basic brackishwater zone is occupying more than half of its area (> 60%)

31. There are offered some hypotheses on which basis position of paleo-barrier salinities in water bodies of Parathetys and ancient Baltic Sea is discussed. An attempt is made to apply main principles of the conception to forecast future scenarios of evolution of water bodies anew formed on the place of divided Aral Sea.

32. 1 2 3 4 5 6 7 8
Water bodies of Paleo-Baltic Sea (by Zenkevich, 1963, with corrections and additions) 1 – maximal phase of the last glaciation; 2- Danish glaciation (15 ths B.P.); 3 – Baltic Glacial Lake (14 ths B.P.); 4 – Yoldia Sea (12 ths B.P.); 5 – Ancylus Lake-Sea (7 ths B.P.); 6 – last phase of Ancylus Lake-Sea (5 ths B.P.); 7 – Littorina Sea (4 ths B.P.); 8 – modern phase (since 2 ths B.P.) Indicated only average salinity without salinity gradient in the Baltic Sea

33. Water bodies of the Palaeocaspian A — Balakhansky (5 mil B. P
Water bodies of the Palaeocaspian A — Balakhansky (5 mil B.P.); B — Akchagylsky (3 mil B.P.); C — Postakchagylsky (> 2 mil B.P.); D — Apsheronsky (2 mil B.P.); E — Tyurkyansky (< 2 mil B.P.); F — Bakinsky (1.7 mil B.P.); G — Venedsky or Ushtalsky (0.5 mil B.P.); H — the Early Khazarsky (400 ths B.P.); I — the Late Khazarsky; J — Atelsky (> 50 ths B.P.); K — the Early Khvalynsky; L — Enotaevsky; M — the Late Khvalynsky; N — Mangyshlaksky (7.5 ths B.P.); O — the New Caspian (5 ths B.P.); P — the present. Indicated only average salinity without salinity gradient

34. Aral Sea: from 9000 to 1600 years BP

35. Aral Sea: from 450 years BP, till now and in the future

36. Changing of the species number in the Baltic Sea following salinity gradient

37. Scheme of aquatic fauna pattern change in water bodies with different salinities (by: Remane, 1934; Khlebovich, 1962; Kinne, 1971; with additions and corrections) 1 – freshwater, 2 – brackish-water, 3 – marine, 4 – hyperhaline and ultrahaline species

38. Changing of the species number following salinity gradient in the Baltic Sea

39. By A.Alimov's formula (n=199.21*S0.155)
Number of fishes, free-living invertebrates and plants without micro-Metazoa, Protozoa and Bacteria in the Baltic Sea
By A.Alimov's formula (n=199.21*S0.155)
From scientific literature by expert evaluation
Baltic Sea Proper
1370
700
Gulf of Finland
982
1000
Bay of Bothnia
1021
1100
Bothnian Sea
1144
1200
Gulf of Riga
896
900
Kattegat
985
4000

40. Decreasing of marine species biodiversity following decreasing of the Baltic Sea salinity

41. Scheme of halopathy of main types of aquatic fauna of Azov and Black Seas basin (by: Mordukhai-Boltovskoi, 1953) Abscissa – salinity, ‰; ordinate axis – number of species

42. Scheme of aquatic fauna pattern change in the Caspian and Aral seas (by: Zenkevich, 1977; Andreeva, Andreev, 2001 with additions and corrections) 1 – freshwater, 2 – brackish-water, 3 – marine species

43. Percentage of different types of osmoconformers and osmoregulators in the World Ocean and fully saline seas as Barents Sea, Sea of Japan, etc.
A1  – Stenohaline marine hydrobionts (osmoconformers I) – 30%
A2  – Marine hydrobionts (osmoconformers II) - 25%
A3  – Euryhaline marine hydrobionts (osmoconformers III) – 15%
B1  – Widely euryhaline marine hydrobionts (confohyperosmotics I) – 5%
B2  – Brackish water hydrobionts of marine origin (confohyperosmotics II) – 3%
C1  – Freshwater hydrobionts (hyperosmotics I) – 0%
C2  – Brackish water hydrobionts of freshwater origin (hyperosmotics II or secondary confohyperosmotics) – 1%
D1  – Some Caspian Brackish water hydrobionts (amphiosmotics I) – 0%
D2  – Some euryhaline Australian hydrobionts of freshwater origin (amphiosmotics II) – 0%
D3  – Euryhaline hydrobionts of freshwater origin (amphiosmotics III) – 1%
D4  – Widely euryhaline hydrobionts of freshwater origin (amphiosmotics IV) – 0%
E  – Euryhaline marine hydrobionts of freshwater origin (hypoosmotics) – 20%

44. Percentage of different types of osmoconformers and osmoregulators in the World Ocean and fully saline seas as Barents Sea, Sea of Japan, etc.

45. Percentage of different types of osmoconformers and osmoregulators in brackish water seas as Black Sea, Sea of Azov, etc.
A1  – Stenohaline marine hydrobionts (osmoconformers I) – 3%
A2  – Marine hydrobionts (osmoconformers II) - 5%
A3  – Euryhaline marine hydrobionts (osmoconformers III) – 10%
B1  – Widely euryhaline marine hydrobionts (confohyperosmotics I) – 10%
B2  – Brackish water hydrobionts of marine origin (confohyperosmotics II) – 15%
C1  – Freshwater hydrobionts (hyperosmotics I) – 5%
C2  – Brackish water hydrobionts of freshwater origin (hyperosmotics II or secondary confohyperosmotics) – 10%
D1  – Some Caspian Brackish water hydrobionts (amphiosmotics I) – 5%
D2  – Some euryhaline Australian hydrobionts of freshwater origin (amphiosmotics II) – 0%
D3  – Euryhaline hydrobionts of freshwater origin (amphiosmotics III) – 5%
D4  – Widely euryhaline hydrobionts of freshwater origin (amphiosmotics IV) – 2%
E  – Euryhaline marine hydrobionts of freshwater origin (hypoosmotics) – 30%

46. Percentage of different types of osmoconformers and osmoregulators in brackish water seas as Black Sea, Sea of Azov, etc.

47. Percentage of different types of osmoconformers and osmoregulators in freshwater lakes as Ladoga, Onega, etc.
A1  – Stenohaline marine hydrobionts (osmoconformers I) – 0%
A2  – Marine hydrobionts (osmoconformers II) - 0%
A3  – Euryhaline marine hydrobionts (osmoconformers III) –0%
B1  – Widely euryhaline marine hydrobionts (confohyperosmotics I) – 0%
B2  – Brackish water hydrobionts of marine origin (confohyperosmotics II) – 0%
C1  – Freshwater hydrobionts (hyperosmotics I) – 98%
C2  – Brackish water hydrobionts of freshwater origin (hyperosmotics II or secondary confohyperosmotics) – 1%
D1  – Some Caspian Brackish water hydrobionts (amphiosmotics I) – 1%
D2  – Some euryhaline Australian hydrobionts of freshwater origin (amphiosmotics II) – 0%
D3  – Euryhaline hydrobionts of freshwater origin (amphiosmotics III) – 0%
D4  – Widely euryhaline hydrobionts of freshwater origin (amphiosmotics IV) – 0%
E  – Euryhaline marine hydrobionts of freshwater origin (hypoosmotics) – 0%

48. Percentage of different types of osmoconformers and osmoregulators in freshwater lakes as Ladoga, Onega, etc.

49. Percentage of different types of osmoconformers and osmoregulators in the Baltic Sea
A1  – Stenohaline marine hydrobionts (osmoconformers I) – 0%
A2  – Marine hydrobionts (osmoconformers II) - 0%
A3  – Euryhaline marine hydrobionts (osmoconformers III) – 5%
B1  – Widely euryhaline marine hydrobionts (confohyperosmotics I) – 15%
B2  – Brackish water hydrobionts of marine origin (confohyperosmotics II) – 24%
C1  – Freshwater hydrobionts (hyperosmotics I) – 14%
C2  – Brackish water hydrobionts of freshwater origin (hyperosmotics II or secondary confohyperosmotics) – 9%
D1  – Some Caspian Brackish water hydrobionts (amphiosmotics I) – 9%
D2  – Some euryhaline Australian hydrobionts of freshwater origin (amphiosmotics II) – 0%
D3  – Euryhaline hydrobionts of freshwater origin (amphiosmotics III) – 10%
D4  – Widely euryhaline hydrobionts of freshwater origin (amphiosmotics IV) – 0%
E  – Euryhaline marine hydrobionts of freshwater origin (hypoosmotics) – 14%

50. Percentage of different types of osmoconformers and osmoregulators in the Baltic Sea

51. The Baltic Sea World Ocean and full-saline seas
Brackish water seas as Black Sea, Sea of Azov, etc.
Freshwater lakes as Ladoga, Onega, etc.
The Baltic Sea

52. Percentage of different types of osmoconformers and osmoregulators in the Western Baltic, Baltic Sea proper and Archipelago Sea
A1  – Stenohaline marine hydrobionts (osmoconformers I) – 0%
A2  – Marine hydrobionts (osmoconformers II) - 0%
A3  – Euryhaline marine hydrobionts (osmoconformers III) – 10%
B1  – Widely euryhaline marine hydrobionts (confohyperosmotics I) – 20%
B2  – Brackish water hydrobionts of marine origin (confohyperosmotics II) – 25%
C1  – Freshwater hydrobionts (hyperosmotics I) – 2%
C2  – Brackish water hydrobionts of freshwater origin (hyperosmotics II or secondary confohyperosmotics) – 5%
D1  – Some Caspian Brackish water hydrobionts (amphiosmotics I) – 10%
D2  – Some euryhaline Australian hydrobionts of freshwater origin (amphiosmotics II) – 0%
D3  – Euryhaline hydrobionts of freshwater origin (amphiosmotics III) – 10%
D4  – Widely euryhaline hydrobionts of freshwater origin (amphiosmotics IV) – 0%
E  – Euryhaline marine hydrobionts of freshwater origin (hypoosmotics) – 23%

53. Percentage of different types of osmoconformers and osmoregulators in the Western Baltic, Baltic Sea proper and Archipelago Sea

54. World Ocean and full-saline seas
Brackish water seas as Black Sea, Sea of Azov, etc.
Freshwater lakes as Ladoga, Onega, etc.
Western Baltic, Baltic Sea proper and Archipelago Sea

55. Bothnian Bay and Bothnian Sea
The Baltic Sea
Kattegat and the Sound
Bothnian Bay and Bothnian Sea
Gulf of Riga
Gulf of Finland
Neva bay

56. Recent invader to the Baltic Sea Evadne anonyx Parthenogenetic female with developing embryos on initial stages in the closed brood pouch

57. Some Caspian Brackish water hydrobionts (amphiosmotics I)
This recent invader could spread all over the Baltic Sea, except of strongly freshened areas of estuaries

58. Recent invader to the Baltic Sea Evadne anonyx Parthenogenetic female with developing embryos on final stages in the closed brood pouch

59. “Old” invader to the Baltic Sea Cercopagis pengoi (Photo by Dr
“Old” invader to the Baltic Sea Cercopagis pengoi (Photo by Dr. Flinkman)

60. Brackish water hydrobionts of freshwater origin (hyperosmotics II or secondary confohyperosmotics)
This old invader already spread over nearly all the Baltic Sea including estuaries, but excluding saline areas such as the Sound and Kattegat

61. Podonevadne camptonyx.
In the nearest future one more Cladocera could appear in the Baltic Sea:
Podonevadne camptonyx.
It has the same type of osmoregulation as
Evadne anonyx.

62. Dike in Berg’s strait funded by GEF and Kazakhstan government allowed to improve brackish water environment of Small (Northern) Aral Sea
1960
1989
2006
2011

63. Prior Ordovician life was only in the ocean
Prior Ordovician life was only in the ocean. So, barrier salinities in this geological time could be distinguished in thalassic waters only. Athalassic waters in this period were still lifeless and there is no sense to speak about barrier salinities in them.
Cambrian thalassic waters were inhabited by trilobites, brachiopods, monoplacophors, hyolithids, and archaeocyatha. However in the late Paleozoic seas crinoids, Echinodermata, brachiopods, graptolites, tabulates and rugose corals.
So, the world of marine invertebrates was highly representative and we suppose the in Ordovician in oceanic water there were at least 3 barrier salinities: α-, β- and γ-horohalinicums.
As for Precambrian, in Archaean and Proterozoic in oceanic waters possibly there was only one barrier salinity (α- horohalinicum).

64. In the late Ordovician life left thalassic waters and got into athalassic ones. The process was started by plants and in Silurian invertebrates and in the late Devonian also vertebrates were next to them. So, to speak about barrier salinities in athalassic waters is possible only since Ordovician.
Maximal number of barrier salinities in athalassic waters is since Cenozoic apparently. Ancient Caspian can be an example. Up to this time specific fauna of continental brackish waters has been formed.
However, even in the early Cenozoic, in thalassic waters there were more barrier salinities (at least 7) while in the athalassic waters they were not more than 5.
Because man contributed to invasion of some representatives of thalassic fauna and flora into athalassic waters, now in continental closed water bodies also it is possible to find more that 5 barrier salinities. So, in the Caspian Sea due to invasion of marine invertebrates and fishes number of barrier salinities has exceeded initial 5.

65. All above-said argumentations are based on evolutionary conception by V.V. Khlebovich (1974, published in Russian)

66. Perfection of osmoregulation capacities in Ostracoda and Branchiopoda in the evolution process Abscissa – geological time; ordinate – extent of hemolymph osmoregulation perfection (by: Aladin, 1986)

67. Nowadays conception of relativity and plurality of salinity barrier zones is originally being developed by Prof. S.I. Andreeva. While positions of her barrier salinities are slightly differ from ours, nevertheless we consider her approach to be constructive. (Andreeva, Andreev, 2001, in Russan)

68. At the conference on the Baltic Sea next year in March (Rostock, Germany) our German colleagues (Steffen Bleich, Martin Powilleit, Torsten Seifert, Gerhard Graf) will report about existence of some barrier salinities (29.5‰, 18.5‰, 10‰, 7.5‰, и 4.5‰) what also testifies to correctness of our approach.
We hope that in the nearest future some barrier salinities will be found in the very narrow range of fresh waters. Conquering by hydrobionts salinity range from 1‰ to almost distilled water was as hard as conquering hyperhaline waters.
There are no doubts that it is important to define precisely lower as well as upper barrier salinities confining distribution of hydrobionts in the hydrosphere.

69. Authors consider that under umbrella of the responsible organizations new meeting should be held in order to reconsider Global Water Classification regarding salinity.
Since last meeting in Venice more than half of century has gone. New data and hypotheses appeared since than. New brain-storm is needed.
Another international meeting is needed. It should be devoted to aquatic ecosystems classification regarding salinity. Such type of meeting was never held before. It is right time to have it.

70. Thank you for your attention