Cilioplankton communities as an indicator of the pollution degree in the Caspian Sea

Бюллетень науки и практики / Bulletin of Science and Practice

UDC 593.17                                         

It is known that the Caspian Sea is the largest inland brackish water body that has no connection with the World Ocean, but nevertheless has all the features of the seas. The modern study of the ciliates of the Caspian Sea was started in the 60s of the XX century by F. Agamaliev, who summarized the long-term results in his monograph [1]. Subsequently, faunistic and ecological studies of free-living ciliates of the Caspian Sea, including planktonic ones, were carried out regularly for many years and were published in the monograph “Cadastre of free-living ciliates and testate amoebae of Azerbaijan” [2].

The species diversity of the Caspian planktons has been exposed to severe anthropogenic stress for many years, which is the result of long-term pollution of the Caspian Sea. Long-term exploration and production of oil in the Caspian Sea has led to severe hydrocarbonic pollution of many water areas of the Absheron Peninsula.

Despite a significant decrease in the level of anthropogenic pressure in recent years, the problem of pollution of the Absheron coast of the Caspian Sea is still relevant. At present, due to the sharply increased process of urbanization of Absheron, sewage pollution is becoming increasingly important.

As is known, free-living protozoa, primarily ciliates, react extremely quickly qualitatively and quantitatively to the slightest changes in the environment, including the degree of technogenic pollution. This feature of ciliates makes it possible to use them for biotesting the degree of pollution of a particular area of marine and freshwater bodies.

Based on the foregoing, a comparative study of the species diversity of communities of planktonic ciliates in various parts of the Caspian littoral of Absheron and a preliminary assessment of the quality of the environment according to the state of planktonic communities of free-living ciliates were conducted.

Material and methods

The material was collected seasonally in 2014-2021 from 6 stationary points on the Absheron coast of the Caspian Sea (Figure 1).

Figure 1. Stationary collection points of plankton samples on the Absheron coast. 1 — Sumgait, 2 — Novkhani, 3 — Bilgah, 4 — Turkan, 5 — Shikh, 6 — Sangachal

A total of 190 plankton samples were collected and processed. To determine the taxonomic affiliation of ciliates, the methods of impregnation with nitrate [3] and silver proteinate [4] were widely used. Bray-Curtis cluster analysis was used to compare the similarity of species diversity in different parts of the coast. The calculations were carried out using the Biodiversity Professional v. 2 computer program.

Results and Discussion

During our research, in the communities of planktonic ciliates of the coastal waters of Absheron, 62 species of ciliates belonging to 22 families were recorded. The composition and distribution of these species are given in Table.

Table

SPECIES COMPOSITION AND DISTRIBUTION OF PLANKTONIC CILIATES ON COLLECTION POINTS IN DIFFERENT COASTAL AREAS OF THE ABSHERON PENINSULA

Species composition                              Occurrence of species in different points

		1	2	3	4	5	6
Ciliophora
Amphisiellidae
1	Amphisiella annulata Kahl, 1928		+			+
2	A. turanica Alekperov et Asadullayeva, 1999		+			+
Euplotidae
3	Euplotes apsheronicus Agamaliev, 1966		+	+	+	+
4	E. baleatus Dujardin, 1842	+			+		+
5	E. gracilis Kahl, 1932		+	+
6	E. charon (Müller, 1773) Ehrenberg, 1830	+			+		+
Aspidiscidae
7	Aspidisca fusca Kahl, 1928	+			+	+	+
8	A. steini Buddenbrock, 1920		+	+
9	A. poljanski Alekperov,1985		+	+
Halteriidae
10	Halteria grandinella (Müller, 1773) Dujardin, 1841		+	+	+
11	Pelagohalteria viridis (Fromentel, 1876) Foissner, Skogstad et Pratt, 1988		+	+		+
Uronychiidae
12	Diophrys scutum (Dujardin, 1841) Kahl, 1932	+			+	+	+
Strombidiidae
13	Limnostrombidium viride (Stein, 1867) Krainer, 1995		+	+			+
14	Novistrombidium testaceum (Anigstein, 1914) Song et Bradbury, 1998		+	+
15	Pelagostrombidium mirabile (Penard, 1916) Krainer, 1991		+	+
16	Spirostrombidium cinctum (Kahl, 1932) Petz, Song et Wilbert, 1995					+	+
17	S. apsheronicum Alekperov et Asad., 1997		+	+

Бюллетень науки и практики / Bulletin of Science and Practice Т. 9. №5. 2023 Species composition Occurrence of species in different points 1 2 3 4 5 6 18 S. elegans (Florentin, 1901) Petz, Song et Wilbert, 1995 + 19 S. elatum Alekperov, 1985 + + 20 S. caspicum Alekperov et Asadullayeva, 1997 + + + 21 Strombidium conicoides (Leegaard, 1915) Kahl, 1932 + + 22 Strombidium claparedi Kent, 1881 + Strombidinopsidae 23 Strombidinopsis elongata Song et Bradbury, 1998 + + 24 S. elegans Song et Bradbury, 1998 + 25 S. azerbaijanica Alekperov et Asad., 1997 + + + Strobilidiidae 26 Rimostrombidium velox (Faure-Fremiet, 1924) Jankowski, 1978 + + 27 R. humile (Penard, 1922) Petz et Foissner, 1992 + Lacrymariidae 28 Lacrymaria olor (Müller, 1786) Bory, 1824 + + 29 Phialina macrostoma Foissner, 1983 + + Didiniidae 30 Monodinium balbianii Fabre-Domergue, 1888 + + + 31 M. perrieri Delphy, 1925 + + + 32 Didinium nasutum (Müller, 1773) Stein, 1859 + + + 33 D. chlorelligerum Kahl, 1935 + 34 D. gargantua Meunier, 1910 + + Trachelidae 35 Paraspathidium obliquum Dragesco, 1963 + + + 36 P. fuscum (Kahl, 1928) Fjeld, 1955 + + + Mesodiniidae 37 Mesodinium acarus Stein, 1867 + 38 M. apsheronicum Alekperov et Asadullayeva, 1996 + + + 39 Mesodinium cinctum Calkins, 1902 + + Nassulidae 40 Nassula marina Alekperov et Asadullaeva, 1997 + + + Colepidae 41 Coleps remanei Kahl, 1933 + + + + 42 C. arenicolus Dragesco, 1965 + + 43 C. lacustris Faure-Fremiet, 1924 + + + + 44 C. nolandi Kahl, 1930 + + + + Urotrichidae 45 Urotricha farcta Claparède et Lachmann, 1859 + + 46 U. armata Kahl, 1927 + + +

Note: 1 — Sumgait, 2 — Novkhani, 3 — Bilgah, 4 – Turkan, 5 — Shikh, 6 — Sangacha

As can be seen from Table 1, the greatest species diversity was observed in the plankton communities of ciliates in the Novkhani (39 species) and Bilgah (36 species) territories. Next in terms of species diversity are the Sangachal (25 species) and Shikh (24 species) sites. The minimum species diversity was noted in the planktonic communities of the Caspian coast at the Sumgait and Turkan territories, where in both cases only 18 species of planktonic ciliates were recorded.

It should be noted that the northern and southern coasts of Absheron differ significantly, primarily in the cleanliness of the coastal zone. The northern coast is less polluted by both oil products and domestic sewage. On the northern coast, areas of pure psammon are still preserved, in the coastal zone there are many rocks with well-developed biofouling. The southern part is heavily polluted by oil products (although in recent years the results of increased monitoring over the cleanliness of the sea have been noticeable). And most importantly, the largest part of all domestic wastewater is discharged on the south coast.

The results of the cluster analysis of the similarity of the species diversity of planktonic ciliate communities are shown in Figure 2. As can be seen from Figure 2, the highest similarity of species diversity (95.5%) was noted for two collection points on the northern coast of Absheron, near the settlements of Novkhani and Bilgah. These sections of the Absheron Peninsula are among the cleanest, despite the increase in the construction of hotels and private houses.

— 3

— 2

--------------------------------- 5

^”^~  

• I-------------------------------------------------------------------------------I1

0 % similarity              50100

• Figure 2. Similarity of species diversity of planktonic ciliate communities in different parts of the Absheron coast of the Caspian Sea (1 — Sumgait, 2 — Novkhani, 3 — Bilgah, 4 — Turkan, 5 — Shikh, 6 — Sangacha)

Comparison of more polluted sites showed the greatest similarity for the coasts of Sumgait and Sangachal (65%). Both of these zones, despite their remoteness, experience a fairly strong pressure of technogenic pollution common to both zones in Sumgait, these are the remains of longterm discharges of the industrial zone, and in Sangachal, a common rather noticeable pollution by both oil products and wastewater from the largest Sangachal oil terminal.

Relatively little similarity was recorded between the collection points listed above and Turkan settlement (61%). This zone, in principle, refers to fairly clean zones. Nevertheless, like all the southern coasts of Absheron, it is polluted by both oil and domestic wastewater due to the wind blowing from the sea.

When comparing these areas with the coast of Shikh, their similarity turned out to be quite close (51.2%), since the causes of the general pollution of the southern coast of the Absheron peninsula are the same in this area.

Conclusion

A comparison of the overall similarity of species diversity of plankton communities between all six stationary sampling points on Absheron showed that it cannot be called high (32.7%). Thus, as a result of the conducted analysis, it was determined that the similarity of species diversity of planktonic ciliate communities on the Absheron coasts clearly differs with two clusters. One combines the cleanest areas of the settlements of Novkhani and Bilgah (95.5%), and all other 4 stationary collection points are combined into the second cluster, the similarity of which is more than 50% for all areas. Characteristically, all collection points on the southern coast of the Absheron peninsula, with the exception of the coast of Sumgait, known as a zone of strong anthropogenic pollution, were included in the cluster that unites the more polluted areas.