In: D.S.Pavlov, Yu.Yu.Dgebuadze,
L.G.Korneva, Yu.V.Slynko (Eds) Invasion of alien species in Holarctic
(U.S.-Russia invasive species workshop 27-31 August, 2001), Borok,
IBIW, 2003: 483-491
BENTHIC ALIEN SPECIES IN THE CASPIAN
SEA: THE INFLUENCE ON BIODIVERSITY
A.A.Filippov & N.V.Aladin
Zoological Institute RAS, 199034 St.Petersburg,
Universitetskaja nab., 1, aral@zin.ru
1. Introduction
The Caspian Sea is the largest epicontinental
water-body of the world. Its area is 436000 km2,
volume is 77000 km3,
maximal depth is about 1000 m (Zenkevich,
1963). The lowered salinity of the Caspian Sea (not exceeding 14 ppt in much of its area) supported
co-existence of a number of fresh-water, brackish-water and marine species.
Overall about 380 species and groups of macroinvertebrates
were registered in benthic assemblages, from which 310 were autihtonic
species (Yablonskaja, 1985).
In 20th century about 18
new benthic species have appeared in the Caspian Sea as a result of spontaneous,
intentional and unintentional men-mediated introductions. Intentional
introductions started from 1930s and were aimed to increase diversity of
invertebrates and to improve a food stock for commercial fishes. Spontaneous
invasion was drastically intensified in 1950s -1960s after the Volgodonskoy and Volgobaltiskiy
Canals were built. These canals connected the Caspian Sea with the Black Sea and the Baltic Sea basins and thus provided the new
routs for invasions (Karpevich, 1975).
Among benthic species appeared in
the Caspian
Sea
recently polychaetes Nereis
diversicolor, bivalves Abra
ovata and Mytilaster
lineatus, decapods Palaemon
elegans and Rhithropanopeus
harrisii, and Cirripedia
Balanus improvisus
occurred in largest amount. After acclimatisation they formed abundant
populations and transformed significantly benthic assemblages throughout the
sea (Yablonskaja, Osadchih,
1996). The data available on these species impact on aboriginal fauna will be
analysed herein.
2. Non-indigenous species and their
impact on aboriginal benthic species
Among all non-indigenous species the
bivalve mollusc Mytilaster lineatus had probably the worst impact on aboriginal
fauna. This species was presumably brought in the Caspian Sea in 1917-1920s during transportation
of small motorboats from the Black Sea to the Caspian Sea (Bogachev,
1928; Shorygin, Karpevich,
1948). In 1920s these molluscs were observed in vicinity of Baku, and also near Krasnovodsk
and Derbent cities. By 1932 mollusc has practically
occupied all regions of the Caspian Sea and in following years it has
become one of leading benthic species.
Abundance of M.lineatus
after acclimatisation has undergone significant fluctuations. In the Southern Caspian Sea mass development of these molluscs
was observed in 1930s-1950s. It reached biomass of 300-500 g m-2,
exceeding abundance of all the other benthic organisms in order of magnitude.
In 1960s-1970s abundance of M.lineatus was reduced
gradually. In 1976 its biomass was 5 g m-2 only and it was no longer
among the dominating species in benthic assemblages.
In the Middle Caspian Sea these
molluscs were observed in abundance in 1940s-1960s (with biomass up to 90-130 g
m-2) but by 1976 the decrease of abundance was reported here too (to
6 g m-2). In the Northern Caspian Sea abundance of M.lineatus
was low (1.8 g m-2 in average) until 1950s. Its essential increase
was observed in late 1950s-early 1960s (up to 30 g m-2) and in
1983-1990 (up to 50 g m-2) (Malinovskaja,
2000). Thus the farther from the place of introduction, the later the peaks of
abundance were registered and the lesser values of maximum biomass were
achieved.
Assessment of M.lineatus
influence on aboriginal species is complicated by the scarcity of quantitative
data on the Caspian
Sea zoobenthos in the period prior his invasion. It is known
that appearance of M.lineatus in the Middle and the Southern Caspian Sea has resulted in complete extinction
of Dreissena caspia
Eichw. and Dreissena elata (Andr.), which were widely spread in these areas before (Logvinenko, 1965). Disappearance of nematode Monhystera bulbosa
Grimm is also alleged to M.lineatus impact (Chesunov, 1983, cited after Chepalyga,
Tarasov, 1997).
After essential reduction of M.lineatus amount in 1970s, abundance of survived
species of Dreissena in the Middle and in the Southern Caspian Sea has been restored, and in the
Middle Caspian Sea they started to dominate again in benthic assemblages (Yablonskaya, Osadchih, 1996).
Thus, the initial adverse effect of M.lineatus
on aboriginal species was subsequently partly repaired.
Polychaete Nereis
diversicolor was intentionally transported into
the Caspian
Sea from
the Azov Sea in 1939, 1940 and 1941. In 1944
worms were found in stomachs of sturgeons caught in a southwest part of the Northern Caspian Sea (Spassky,
1945), and in 1945 they were found in benthos of the Northern Caspian Sea as well (Shorygin,
Karpevich, 1948). In the following years worms have
spread all over the Caspian Sea (Yablonskaja, 1985).
In the Northern Caspian Sea gradual
increase of N.diversicolor biomass (from 1.6 g
m-2 up to 4.1 g m-2) was observed in 1940s-1980s but by
the end of 1990 it has dropped down to 1.5 g m-2 (Malinovskaja, 2000). In the Middle Caspian Sea in
1950s-1970s N.diversicolor biomass varied
between 2 and 3 g m-2 (Yablonskaja, Osadchih, 1996) but in 1980s some decrease of its abundance
was observed also (down to 1 g m-2 by 1987) (Romanova,
Osadchih, 1994). In the Southern Caspian Sea, as well as in the Northern Caspian, in 1960s-1970s the growth of N.diversicolor abundance (from 1 up to 6 g m-2)
was observed (Yablonskaja, Osadchih,
1996). Further dynamics of Nereis populations in the Southern Caspian Sea is poorly known.
Considering the effect of N.diversicolor introduction, most authors agreed
that it did no affect negatively the aboriginal fauna (Birshtein,
Spasskiy, 1952; Saenkova,
1956; Karpevich, 1975). Some reduction of Chironomidae and Oligochaeta
abundance after introduction of this polychaete was
observed but this was not considered as sufficient evidence of N.diversicolor unfavourable influence. Nevertheless,
detailed analysis of both spatial distribution and seasonal dynamics of
indigenous forms in the Northern Caspian Sea performed by other authors (Lebedev, 1955) clearly indicated negative influence of N.diversicolor on Chironomidae,
Oligochaeta, Amphipoda and Adacna. This impact was expressed in both decrease of
average abundance and displacement of indigenous species from common habitats
by the newcomer. Clear spatial segregation of N.diversicolor
and Chironomidae was also observed here (Lebedev, 1955).
In the Middle and the Southern Caspian Sea the structure of benthic
assemblages has changed also. In the Middle Caspian Sea the distribution of N.diversicolor was accompanied by essential
reduction of Chironomidae biomass (from 0.5 g m-2
in the middle 1930s to 0.05 g m-2 in 1976). Apart from this negative
correlation in long-term dynamics, the obvious segregation of habitats occupied
by Chironomidae and N.diversicolor
was observed here also (Yablonskaja, 1985).
The low abundance of Chironomids in the Southern Caspian Sea complicated analysis of
acclimatised species influence. Hence the examination of only those particular
areas, where these species were abundant would be most useful. In his
description of 1874 Caspian Sea voyage Grimm (1876) has mentioned, that in the Bay of Krasnovodsk and the Balhansky
Bay Charophyta "… is occupied mainly by red Diptera larvae (obviously, Chironomidae,
A.F.)" (Page 42).
Explorations carried out in this particular area in 1970s showed that Chironomidae were very rare here (Nikitina,
Vasiliev, 1979). Reconstruction of palaeocenoses showed significant reduction of Chironomidae abundance by middle of 20th century
in this area (Chepalyga, Tarasov,
1997). This could only be attributed to Nereis
impact.
Bivalve mollusc Abra
ovata was intentionally delivered into the Caspian Sea in 1940, 1947 and 1948 (Karpevich, 1975). For the first time the molluscs were
found only in 1955 in the Northern Caspian Sea, and after that their spread down the coasts
was observed (Saenkova, 1956; Karpevich,
1975).
In the Northern Caspian Sea in
1940s-1970s an increase of A.ovata biomass was
observed with maximums in the late 1950s and in the end of 1970s (16 and 26 g m-2
accordingly) (Yablonskaja, Osadchih,
1996). In 1990s some reduction of its abundance on a background of essential
fluctuations took place (Malinovskaja, 2000). In the
Middle Caspian Sea maximal abundance of these molluscs was registered in 1962
(62 g m-2), while in 1970s some biomass decrease and subsequent stabilisation
at the level of 7-12 g m-2 were observed (Romanova,
Osadchih, 1994). In the Southern Caspian Sea biomass increase (up to 74,5 g m-2) was observed in 1950s-1970s (Yablonskaja, Osadchih, 1996). In
1980s some reduction of A.ovata abundance was registered
here as well (Romanova, Osadchih,
1994).
Thus, just as well as in case of Mytilaster, essential fluctuations of A.ovata
abundance were observed with maximums registered the later the farther from the
place of delivery they were observed.
Introduction of A.ovata
in the Caspian
Sea was
usually considered as taken place without any adverse effect on indigenous
species (Zenkevich, 1963; Karpevich,
1975). Only few authors (Chepalyga, Tarasov, 1997) expressed the opposite point of view. They
suggested that A.ovata has replaced Cerastoderma and autichtonic
Caspian Cardiidae in their original habitats. Such
replacement, in their opinion, became possible due to the greater
competitiveness of A.ovata, who possess higher
filtration rate and are able to survive in conditions of oxygen deficiency.
Nevertheless the evidences of competitive relations of Abra
with atichtonic Cardiidae
species (Hypanis) were not clearly cut and need
further investigation. As for the replacement of Cerastoderma
by A.ovata, this process is shown to have
short-term and reversible character (Zenkevich, 1947;
Romanova, 1979; Filippov,
1995) and hence could hardly be considered as example of negative impact.
The shrimps Palaemon
adspersus and P.elegans
were brought into the Caspian Sea unintentionally in 1931, 1933 and 1934 during acclimatisation of the
mullet (Shorygin, Karpevich,
1948). In late 1930s they were registered in abundance near the western coasts
of the Middle Caspian Sea (Bening, 1936; Makarov, 1940). Afterwards shrimps were reported from
around the Sea except areas of lowered salinity in the Northern Caspian (Karpevich,
1975). Quantitative data on shrimp abundance in the Caspian Sea are very scarce. It is known that
these crustaceans were very often observed in high abundance (Karpevich, 1975), their biomass in Southern Caspian could reach 166 g m-2 (Kasymov, 1987)
Assessment of shrimp impact on
aboriginal Caspian species is hampered by scarcity of data about their
abundance. Zenkevich (1963) believed that shrimps
could compete with Myzidacea. Since the most part of
shrimp ration comprised benthic invertebrates (Malinovskaja,
1961), they could possibly facilitate reduction of indigenous species
populations. It is noteworthy at the Aral Sea P.elegans is
considered to be the main cause of extinction of the only amphipod species
there, Dikerogammarus aralensis
(Khusainova, 1968; 1971). Nevertheless, in the Caspian Sea no evidence was revealed of
unfavourable impact of shrimps on indigenous benthic species.
Crab Rhithropanopeus
harrisii appeared in the Caspian Sea after the Volgodonskoy
canal has been built. For the first time R.harrisii
was found in the Caspian Sea in 1958 near the Kulaly Island. Out of the Northern Caspian Sea the crab was brought by ships (adults)
and by cyclone current (larvae) along western coast of the Middle Caspian Sea
and further all around the sea. In the mid-1960s the crab became one of main
components of zoobenthos assemblages throughout the
Sea, reaching biomass of 80 g m-2 and number of 240 ind m-2 (Yablonskaja,
1985).
Crab influence on the indigenous
fauna of the Caspian
Sea is
also poorly understood. Being omnivorous species it can eat small crustaceans,
worms, hydroids, small molluscs, though vegetation and mollusc juveniles prevail
in his diet. Thus, his impact on benthic assemblages can be very essential and
similar to that of benthos-eating fishes (Yablonskaja,
1985). Some palaeolimnological data suggest that
crabs were responsible for recent reduction of abundance of small gastropods
(family Hidrobiidae) in the Southern Caspian Sea (Chepalyga,
Tarasov, 1997). This suggestion is supported by the
data about reciprocal spatial distribution of these crabs and Hidrobiidae in the Aral Sea (Filippov, 1995).
Nevertheless, there is not enough data for definite conclusion and this
suggestion needs to be thoroughly examined.
Balanus improvisus and B.eburneus
as well as many other invasive species had penetrated the Caspian Sea after constructing the Volgodonskoy canal. B.improvisus
was found for the first time in the Northern and the Middle Caspian Sea in 1955
(Saenkova, 1956), and in one year it
has spread all over the Caspian Sea. B.eburneus was found in the Caspian Sea for the first time in 1956 (Zevina, 1957). Recently these
organisms were constantly observed in fouling communities, forming biomass of
up to 10 kg m-2 (Zevina, 1979)
Balanus invasion was probably the only
example of favourable impact of alien species on indigenous fauna. Some authors
(Osadchih, 1963; Zevina,
1968b) pointed out that distribution of Balanus in
the Northern
Caspian Sea
has not resulted in replacement of aborigines,
moreover, abundance of some indigenous species has increased due to its
appearance. Balanus shells transformed natural
habitats and improved environmental conditions for some species in terms of
better protection against wave activity and consumption by fishes, besides they
provided additional surface for attachment of some sedentary species (Karpevich, 1975).
3. Conclusion
As it was shown above, after the
introduction of some new species in the Caspian Sea significant inter-annual
fluctuations of abundance of dominating benthic species (both indigenous and
invasive) were observed in all parts of the Caspian Sea. Since such fluctuations took place
on a background of relatively stable hydrological regime, it was possible to
assume that they were caused by biological factors. This biological factor
could be the misbalance of the Caspian ecosystem due to appearance of a new
species. Among recent invaders only M.lineatus
has probably caused extinction of aboriginal species. No other case of
aborigine extinction due to invaders was reported. Thus overall the
introduction of new species has probably led to increased biodiversity of the Caspian Sea benthic assemblages.
Nevertheless the chances are high that future invaders could still cause the
extinction of aboriginal species or put them at risk via reduction of their
populations. Taking into account the high value of the Caspian Sea aboriginal fauna
on one hand and intensification of spontaneous invasions as well as
unpredictable character of the new species impact on the other hand it is
absolutely clear that special program on the prevention of non-planned
invasions to the Caspian Sea should be elaborated.
4. Acknowledgements
The research was partly supported by
the Russian Foundation for Basic Research (Project N 01-04-49550).
5. References
Antsulevich A.E.
and Starobogatov Ya.E. First finding of molluscs from order Nudibranchia (=Tritoniformes) in
the Caspian Sea. Russian Journal of Zoology.
1990; 69(11): 138-140 (rus).
Bening A.L. Penetration of some new species into the Caspian Sea. Priroda. 1936(4): 107-108 (rus).
Birshtein Ya.A. and
Spassky N.N. Benthic fauna
of the Caspian Sea before and after introduction of Nereis
succinea. Introduction of
Nereis in the Caspian Sea. Moscow: Izdatelstvo MOIP; 1952: 115-145 (rus).
Biserova L.I. Occurrence and spatial distribution of Lithoglyphus naticoides
(Gastropoda, Lithoglipidae)
in the delta of Volga River. Russian Journal
of Hydrobiology. 1990; 26(2): 98-100 (rus).
Bogachev V.V. Mytilaster in the Caspian Sea. Russian Hydrobiological Journal. 1928: 187-189 (rus).
Chepalyga A.L. and Tarasov A.G. Introduction of Atlantic soecies
in the Caspian
Sea : the fate of indigenous taxa
and biosystems. Russian Journal of
Oceanography. 1997; 37(2): 261-268 (rus).
Filippov A.A. Macrozoobenthos of inshore zone of the Aral Sea North in
modern polyhaline conditions: density, biomass and
spatial distribution. Proceed.of Zool.Inst.
1995, 262: 103-166 (rus).
Grimm O.A. The Caspian Sea and its fauna. S.Petersburg; 1876; Notebook 1 p. 168. (Grimm A.O. Trudy Aralo-Kaspiyskoy ekspedicii; v.
Issue 2 Attachment to the proceedings of St.Petersbug
Society of Natural Hystory) (rus).
Karpevich A.F. The theory and praktice of
acclimatization of water organisms. Moscow: Pischevaja
Promyshlennost; 1975; p. 432.
Kasymov A.G. Animal world of
the Caspian Sea. Baku: Elm; 1987: p. 155 (rus).
Khusainova N.Z.
Biological basis for fish and invertebrate acclimatisation in the Aral Sea . Fish and
invertebrate acclimatisation in water-bodies of USSR. Moscow; 1968: 100-104 (rus).
Khusainova N.Z. Recent changes in
biological processes in the Aral Sea. Biological Sciences. 1971; 1: 176-190 (rus) Alma-Ata.
Lebedev N.V. About
mutual relation of Nereis succinea with the aboriginal forms of benthos of the Northern Caspian Sea. The Bulletin of the Moscow University. A Series of Physical, Mathematical
and Natural Sciences. 1955; 1(2): 89-118 (rus).
Logvinenko B.M. New
invasive species in the Caspian Sea. Priroda. 1959; 2: 100-101 (rus).
Logvinenko B.M. About changes in a fauna of the Caspian molluscs of genus Dreissena after introduction Mytilaster
lineatus (Gmel).
Biologicheskie Nauki. 1965; 4: 14-20 (rus).
Makarov A.K. New
species in the Caspian sea, the Black Sea shrimp. Priroda. 1940(4): 84 (rus).
Malinovskaja A.S. On biology of shrimps
acclimatised in the Aral Sea Papers on Ichthiology
and Hydrobiology. Alma-Ata: Izdatelstvo AN KazSSR; 1961: 113-124 (rus).
Malinovskaja L.V. The
role of acclimatizants in constructing of benthic
fauna of the Northern CaspianMatishov G.G., Ed. Introduced species in the European Seas of
Russia. Scientific Workshop; 2000 Jan 27-2000 Jan 28; Murmansk. Murmansk: MMBI KNC RAN; 2000: 57-59 (rus).
Naumov V.D. Coelenterata. Guidebook on the Caspian Sea invertebrates. Moscow: Pischevaja
Promyshlennost; 1968: 43-50 (rus).
Nebolsina T.K. The Crab in the Caspian Sea. Priroda. 1959;
6: 116 (rus).
Nikitina E.N.
and Vasiliev V.I. Benthic
invertebrates of the Bay of Krasnovodsk and their role in
providing feeding plots for wintering waterfowl. Maev E.G., Ed. Integrated
Research of the Caspian
Sea. Moscow: MGU; 1979: 119-123 (rus).
Orlova M.I., Khlebovich V.V., Komendantov A.Yu. Potential eurihalinity
of Dreissena polymorpha
(Pallas) and Dreissena bugensis
(Andr.). Russian Journal of
Aquatic Ecology. 1998; 7: 17-28.
Osadchikh V.F.
Benthos of Northern Caspian after the
regulation of Volga outflow. Russian Journal
of Zoology. 1963; 42(2): 184-197 (rus).
Romanova N.N.
About the relationship between Cerastoderma lamarcki and Abra ovata along the westen coast
of Northern
Caspian. Molluscs. Abstracts of oral presentations, 6, St.Petersburg. St.Petersburg: 1979: 109-110 (rus).
Romanova N.N. and Osadchih V.F. Long-term
fluctuations in benthic assemblages of the Middle and Southern CaspianAlexeev A.P., Ed.
Ecosystems of the Seas of Russia under conditions of antropogenic
press; 1994 Sep 20-1994 Sep 22; Astrahan. Astrahan: KaspNIRH; 1994: 189-191
(rus).
Saenkova A.K. New species in the Caspian Sea fauna. Russian Journal
of Zoology. 1956; 35(5): 678-679 (rus).
Saenkova A.K.
Monodacna colorata in the Caspian Sea. Priroda. 1960(11): 111 (rus).
Shorygin A.A. and Karpevich A.F. New acclimatisants in the Caspian Sea and their
significance for the Sea biology. Simferopol: Krymizdat;
1948; p. 107 (rus).
Spasskiy N.N. First finding of Nereis succinea in the Northern Caspian. Russian Journal
of Zoology. 1945; 24(1): 33 (rus).
Yablonskaja E.A., Ed. The Caspian Sea. Fauna and biological productivity.
Moscow: Nauka; 1985; p. 277 (rus).
Yablonskaya E.A. and Osadchikh V.F. Effect of the oceanographic conditions on benthos
development. F.S.Terziev, Ed. Hydrometheorology and
hydrochemistry of the Seas. V.6 The Caspian Sea. 2. Hydrochemical
conditions and oceanographic fundamentals of biological productivity
development. St.Petersburg: Hydrometeoizdat;
1996: 263-278 (rus).
Zenkevich L.A. Seas of the USSR 2. The fauna and biological
productivity of the Sea. Moscow-Leningrad: Sovjetskaja
Nauka; 1947; p. 588 (rus).
Zenkevich L.A. Biology of
the Seas of the USSR. Moscow: Nauka;
1963; p. 739 (rus)
Zenkevich L.A., Birshtein Ya.A., and Karpevich A.F. First outcome of
reconstruction of the Caspian Sea fauna. Russian Journal
of Zoology. 1945; 24(1): 25-30 (rus).
Zevina G.B. Balanus improvisus Darwin and B.eburneus
Gould) on hydro-engineering constructions of the Caspian Sea. Doklady AN SSSR.
1957; 113(2): 450-453 (rus).
Zevina G.B. New organisms in the Caspian Sea. Priroda. 1959(7): 79-80 (rus).
Zevina G.B.
Caspian Sea fouling assemblages and their fluctuations for the last ten years
(from 1951 to 1961). Russian Journal of Oceanography. 1962; 2(4): 715-726 (rus).
Zevina G.B. Enteroprocta. Guidebook on the Caspian Sea invertebrates. Moscow: Pischevaja
Promyshlennost; 1968a: 65-67 (rus).
Zevina G.B. The role of introduced species in fouling communities of the Caspian Sea. Acclimatisation
of fishes and invertebrates in water-bodies of USSR. Moscow; 1968b: 86-94 (rus).
Zevina G.B.
Acclimatisants and auto-acclimatisants
in the Caspian Sea. Integrated explorations of
the Caspian Sea. Moscow: MGU; 1979: 108-119 (rus).
Table.
Non-indigenous species in the Caspian Sea benthic assemblages
|
№
|
Species
|
Abundance
|
Donor area
|
Way of intr.
|
Year of introd.
|
References
|
|
|
Hydrozoa
|
|
|
|
|
|
|
1
|
Blackfordia virginica
Mayer
|
++
|
B-A
|
Ac
|
1950s
|
Logvinenko, 1959
|
|
2
|
Bougainvillia megas (Kinne)
|
++
|
B-A
|
Ac
|
1950s
|
Zevina, 1962
|
|
3
|
Moerisia maeotica
(Ostroumov)
|
++
|
B-A
|
Ac
|
1950s
|
Naumov, 1968
|
|
|
Kamptozoa
|
|
|
|
|
|
|
4
|
Barentsia benedeni
(Foetinger)
|
++
|
B-A
|
Ac
|
1950s
|
Zevina, 1968 a
|
|
|
Polychaeta
|
|
|
|
|
|
|
5
|
Nereis
diversicolor O.F.Muller
|
+++
|
A
|
Int
|
1939
|
Zenkevich et al., 1945
|
|
6
|
Mercierella enigmatica
Fauvel
|
+++
|
B-A
|
Ac
|
1950s
|
Zevina, 1962
|
|
|
Cirripedia
|
|
|
|
|
|
|
7
|
Balanus improvisus
Darwin
|
+++
|
B-A
|
Ac
|
1950s
|
Saenkova, 1956
|
|
8
|
В.eburneus Gould
|
+++
|
B-A
|
Ac
|
1950s
|
Zevina, 1957
|
|
|
Decapoda
|
|
|
|
|
|
|
9
|
Palaemon elegans Rathke
|
+++
|
B
|
Ac
|
1930s
|
Makarov, 1940
|
|
10
|
P.adspersus (Rathke)
|
+++
|
B
|
Ac
|
1930s
|
Bening, 1936
|
|
11
|
Rhithropanopeus harrisii
(Gould)
|
+++
|
B-A
|
Ac
|
1950s
|
Nebolsina, 1959;
|
|
|
Bivalvia
|
|
|
|
|
|
|
12
|
Mytilaster lineatus
(Gmel.)
|
+++
|
B
|
Ac
|
1920s
|
Bogachev, 1928
|
|
13
|
Dreissena bugensis
(Andr.)
|
++
|
B-A
|
Ac
|
1990s
|
Orlova et al., 1998
|
|
14
|
Abra ovata (Phil.)
|
+++
|
A
|
Int
|
1940
|
Saenkova, 1956
|
|
15
|
Monodacna colorata
(Eichw.)
|
++
|
A
|
Ac
|
1950s
|
Saenkova, 1960
|
|
|
Gastropoda
|
|
|
|
|
|
|
16
|
Lithogliphus naticoides
Pfeiffer
|
+
|
B-A
|
Ac
|
1960s?
|
Biserova, 1990
|
|
17
|
Tenellia adspersa
(Nordmann)
|
++
|
B-A
|
Ac
|
1980s?
|
Anzulevitch, Starobogatov,
1990
|
|
|
Bryozoa
|
|
|
|
|
|
|
18
|
Conopeum seurati
(Canu)
|
+++
|
B-A
|
Ac
|
1950s
|
Zevina, 1959
|
Notes: Donor area as A, the Azov Sea, B, the Black Sea; Way of introduction as Ac,
accidental, Int, intentional; Abundance: +, rare
species, ++, common species, +++, abundant species.
