Meiobenthos Of The Black Sea Anaerobic Zone
MEIOBENTHOS OF THE BLACK SEA ANAEROBIC ZONE
N.G. Sergeeva
Institute of Biology of the southern Seas, NASU, Sevastopol
From the moment of reveal of the hydrogen sulphide zone in the Black sea and up to the present time it is adopted that its depths are lifeless, that in the hydrogen sulphide there was no life, exept microbial. The results of the deep-water silts studies proved it. In the Black Sea hydrogen sulphide silts only remnants of different plankton organisms were found (Andrusov, 1894, Archangelsky, Strakhov, 1938). A special study of the composition of so called “rain of cadavers” at different pelagial horizons and in the surface layers of silts (Kriss, 1959) permitted to describe only remnants of 8 groups of plankton organisms in the silts of the Black sea central deep water bottom part.
For many tens of year\’s lifelessness of the deep hydrogen sulphide zone of the Black Sea was considered by the world science as real truth. At determined planning of hydrobiological researches only to the depths, where water still contains solubilized oxygen, at least in minimum concentrations (the zone of co-existance, or redox-zone). In connection with these studies of benthic organisms in the Black Sea deep-water zone remained out of hydrobiologists attention.
Depending on vertical distribution of size-ecological groupings of the Black sea zoobenthos they used to separate three belts: 1-st-from water margin to 120–150 m depth, inhabited with organisms of macro-, meio- and microbenthos, 2-nd-from 12—150 m to 250–300 v, where only meio – and microbenthos organisms live, 3-rd, - from 250–300 m to maximum depths, inhabitated exclusively by microbenthos (bacteria) [Kisseleva, Makkaveeva, 1971, Kisseleva, 1979).
Up to the results of benthic studies in the Black sea north-western part, the range of the second belt appeared to be much more wide-up to 645 m [Sergeeva, 1988]. At the station, connected with the given depth, they found benthic organisms (nematoda and tanaida, with number of 1000 and 670 ex×m-2 correspondingly), and in water they registered oxygen and hydrogen sulphide content (0,1 and 6,8 mg×l-1, correspondingly). According to Yu.P. Zaitsev et al.
[1987] at the depth of 600 m at the same region there live nematode of three genera Desmoscolex, Tricoma and Cobbionema.
The mentioned above data on multicell animals found in the hydrogen sulphide zone and on small concentrations of oxygen in the deep water, which admit life activity of some groups of animals, permitted to advance a hypothesis of a possibility of meiobenthos inhabitation in the Black sea anaerobic region. To check these hypothesis additional researches of the bottom sediments in the Black Sea hydrogen sulphide region were fulfilled at wide range of depths (350–2250 m).
The studies conducted of deep-water bottom sediments at 25 stations during 1985–1999 permitted the author to receive the data on variable, partially peculiar population of the Black Sea hydrogen sulphide region. It appeared that benthos of the anaerobic zone is represented by usual Black sea species, characteristic for the shelf zone, and hydrobionts, earlier unknown for the Black sea and science.
They found about 40 representatives of benthic organisms, identified up to species or generum, family, detachment, and 20 forms, taxonomically identified conditionally (table 1 and 2).
Table 1. Taxonomic composition and distribution of organisms according on the Black Sea shelf and on anaerobic region
Taxons
Depth, m
470-570
600-700
1300-1340
1700
1800- 2000
2080-2121
2250
1.
2.
3.
4.
5.
6.
7.
8.
Phaeophyta
Ectocarpus sp.1
+
Ciliophora
Folliculina sp 1
+
Tintinnopsis .sp.1
+
Sarcomastigophora
Foraminifera
Streblus beccarii (Linne)
+
+
Allogromiinae g.sp
+
Nemathelminthes
Nematoda
Neochromadora sabulicola (Fil.)
+
+
Chromadora sp.1
+
+
+
Ch. nudicapitata Bast.
+
Euchromadora striata (Eber.)
+
1.
2.
3.
4.
5.
6.
7.
8.
Chromadorida gen.sp
+
Monoposthia costata (Bast.)
+
Microlaimus kaurii Wieser
+
+
Cobbionema sp.1
+*
Quadricoma loricata Fil.
+
Desmoscolex sp.
+*
Tricoma sp
+*
Theristus sp.
+
Eurystomina assimilis (De Man)
+
+
+
Enoplus quadridentatus Berl.
+
Oncholaimus sp. 1
+
O. dujardinii De Man
+
Enoploides cf. brevis Fil.
+
Cephalorhyncha
Kinorhynсha
+
Mollusca
Bivalvia gen. sp., juv.
+
Arthropoda
Crustacea
Harpacticoida
+
+
+
+
+
Ectinosoma melaniceps Boeck
+
+
Laophontidae g.sp.
+
Parastenhelia spinosa (Fischer)
+
Harpacticus sp.1
+
Amphipoda
Gammaridea g.sp.
+
Caprellidea g.sp.
+
+
Anisopoda
Apseudopsis ostroumovi Bac. et Car.
+
+
Tanais cf. cavolini Milne-Ed.
+
Ostracoda g.sp.
+
Arachnida
Acarina
+
+
+
+
Halacarae g.sp..
+
Pontarachna punctulum Phil.
+
Halacarus basteri Troues.
+
Thus the data presented testify to the fact that the bottom surface of the hydrogen sulphide region is inhabited by rich fauna, which includes different trophic groupings.
A specific deep-water fauna differs considerably from the fauna of the Black Sea upper horizons. It means, that multi-cell population of the anaerobic zone is represented by usual species of the Black Sea shelf and by endemics of deep hydrogen sulphide region. Occurrence of the same organisms at great range of depths testifies to a real existence in the hydrogen sulphide zone of a more highly organized life than a bacterial one. It can be, that we have not considered the
Table. 2. Distribution of benthic unknown organisms on anaerobic region
Organisms
Depth, m
470-570
600-700
1300-1340
1700
1800- 2000
2080-2121
2250
1.
2.
3.
4.
5.
6.
7.
8.
Class Krassilnikoviae Kriss & Mitz.
Microorganism A,
+
Microorganism B
+
Type Cyanophyceae ( ?)
Cyanophyceae g.sp.1
+
Cyanophyceae g.sp..2
+
Type Phaeophyta (?)
Phaeophyta g.sp.
+
Protozoa (?)
Form 1
+
+
+
+
Form 2
+
Type Ciliophora (?)
Form 3
+
+
+
+
+
+
Type Sarcomastigophora (?)
Foraminifera (?)
Form 4 sp. 1
+
+
+
+
Form 4 sp. 2
+
+
+
Form 5
+
Type Annelida (?)
Form 7
+
Type sp.1
Form 6
+
+
+
+
Form 8
+
+
+
Form 9
+
+
Form 10
+
Form 11
+
+
+
+
+
+
+
Type Arthropoda
Class Arachnida
Form 12
+
1.
2.
3.
4.
5.
6.
7.
8.
Form 13
+
+
+
Form 14
+
Type sp.2
Form 15
+
+
+
+
+
+
population of the hydrogen sulphide zone adequately, and it can be still more diverse and numerous. But at the given stage of researches it is obvious; that specific meiobenthic communities exist in anaerobic region at great dephths in the Black sea, and they, due to power of their ecological-functional characteristics, are adapted to a highly toxic hydrogen sulphide zone as inhabitat. The “rain of cadavers”, getting to the deep hydrogen sulphide zone, is used not only by microflora, but by benthic organisms as well.
References
1. Andrusov N.I. On hydrogen sulphide fermentation in the Black Sea/Notes Imper.Acad.Sci., Section phys.,-mat. 1894.-VIII.-1.-P.1-10. (in rus.)
2. Archangelsky A.D., Strakhov N.M. Geological construction and a history of the Black Sea development. M.-L.,1938.-226p
3. Zaitsev Yu.P., Antsupova L.V., Vorobyova L.V., Garkavaya G.P., KulakovaI.I., Rusnak E.M. Nematoda in the Black Sea deep-water part // Reports Ukr. Acad. Sci.-Series B, 1987.-11.-P.77-79.
4. Kisseleva M.I. Zoobenthos/In: The bases of the Black Sea biological productivity.-Kiev: Nauk.dumka.-1979.-P.208-241.
5. Kriss A.E. Marine microbiology (deepwater).-M. Publ house USSR Acad.Sci., 1959.-455 p.
6. Sergeeva N.G. On reveal of the bottom invertebra at great depths in the Black Sea// III All-Union conf. On marine biology (Sevastopol, Oct.18-20, 1988). Reports theses.-Kiev, Nauk dumka,1988.- P.246-247
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