Alien fishes in the Black Sea waters of Crimea (Ukraine)

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National Museum of Natural History NAS of Ukraine (Kyiv, Ukraine)

Alien fishes in the Black Sea waters of Crimea (Ukraine)

Leonid Manilo



Alien fishes in the Black Sea waters of Crimea (Ukraine). L. Manilo

Abstract

The paper is devoted to alien fish species that have appeared in coastal waters of the Black Sea near Crimea for the past 50 years. The fish fauna of the Black Sea mainly comprises species that represent the Ponto-Caspian and Atlantic-Mediterranean faunal complexes. According to the generalised literature data, 158 fish species of 107 genera of 60 families have been recorded in the Black Sea since the publication of K.F. Kessler's work (Kessler 1877), all of them representing the Atlantic-Mediterranean complex. In waters of Crimea, 116 species of 86 genera of 51 families have been recorded for the same period. A full checklist of fishes of this complex is presented indicating 31 alien species that have appeared since the 1970s and which belong to 27 genera and 16 families. In waters of Crimea, alien fishes make up 26.5 % of all species, 31.0 % of all genera, and 31.4 % of all families of the Atlantic-Medirranean complex. According to the level of their occurrence in marine waters of Crimea, all recently introduced species are grouped into three categories: regular, sporadic, and casual. Their brief characterisics are given, including synonymy, representation in the fish collection of the NMNH NASU, brief description, distribution, and vector of introduction. It was found that benthic species predominate among introduced fishes that occur regularly in waters of Crimea (12 species, or 80.0 %), while bentho-pelagic and pelagic species are less represented (6.7 % and 13.3 %, respectively). Pelagic and bentho-pelagic species prevail (50.0 % and 37.5 %, respectively) among fishes that occur sporadically. Bentho-pelagic species predominate (57.1 %) among fishes that occur casually. It was discovered that among the 31 alien fishes recorded in the Black Sea waters of Crimea for the past 50 years predominate those that have appeared here due to the natural process of mediterranisation (22 species, 71.0 %). It was imposibble to determine the vector of introduction of 4 species (12.9 %). The appearance of 5 species, which represent 16.1 % of all alien species, is related to anthropogenic factors. It can be also concluded that benthic species predominate among the alien fishes (14 species, or 45.2 %), while bentho-pelagic (9 species) and pelagic (8 species) fishes make up 29.0 % and 25.8 %, respectively. Of the 31 introduced fishes, 10 (32.2 %) have naturalised and acclimatised in marine waters of Crimea and have founded independent breeding populations. Among them, representatives of the family Gobiidae notably prevail, followed by the taxonomically close family Oxudercidae, whereas one species belongs to the family Blenniidae. The so-iuy mullet, which is the only representative of the pelagic ecological group, was introduced intentionally.

Key words: fishes, alien species, introduction, distribution, acclimatisation, mediterranisation, Ukraine, Crimea.



To the memory of my dmr colleague A.R. Boltachev (21.07.195230.01.2019), the famous Ukrainian and Russian ichthyologist

Introduction

eutrophication sea ichthyofauna

The fish fauna of the Black Sea is being constantly enriched with new representatives of the Atlantic-Mediterranean faunal complex, a process called “mediterranisation” (Puzanov 1967). This permanent process related to the specific history of formation of this water basin has lasted about 7000-8000 years since the latest connection of the Novoevksinske Lake-Sea with the Mediterranean Sea (Zaytsev 2006) opening a corridor for the spread of the Mediterranean fauna.

Coastal waters of the Crimean Peninsula are characterised by the highest diversity of the fish fauna compared to other regions of the Black Sea, which is related to the geographic location of the peninsula that extends southward to about the middle of the Black Sea, as well as to various abiotic and biocoenotic features. The species composition of fishes in this area, as well as in many other regions, has undergone notable changes due to natural and anthropogenic factors.

Records of alien species in the Black Sea has significantly increased in number over the past decade, including coastal waters of Crimea where a notable number of fishes that are new for the ichthyofauna of the Azov-Black Sea Basin and which belong to the Atlantic-Mediterranean and other faunal complexes has been recorded.

It should be mentioned that in addition to such Atlantic-Mediterranean species as the salema porgy Sarpa salpa (Boltachev & Karpova 2014), sand steenbras Lithognathus mormyrus (Boltachev et al 2013), zebra goby Zebrus zebrus (Manilo et al. 2013), and Baths goby Pomatoschistus bathi (Boltachev & Karpova 2010), species of the Indo-West Pacific region are also recorded in the Black Sea. The latter has spread through the Suez Canal and eastern part of the Mediterranean Sea (Lessepsian migrants), some of them dispersed to the Aegean, Marmara, and Black Sea. Exapmles of these species are the red barracuda Sphyraena pinguis (Boltachev 2009) and the silver-cheeked toadfish Lagocephalus sceleratus (Boltachev & Karpova 2017). Some species have found favourable conditions in the Black Sea and are at different stages of acclimatisation or have already founded stable breeding populations.

Over the past decades, marine ecosystems of Ukraine have been under constant anthropogenic impact, including pollution and various forms of economic activity. Increased euthrophication of the sea, which has started in the 1970s, increased recreational activity on the coasts, development of fishery, increased shipping, and other factors have led to negative consequences that affected the fish fauna of the northern part of the Azov-Black Sea Basin. Due to anthropogenic impact and along with the general degradation of ecosystems in recent years, a change in species composition of fishes took place practically in all parts of this region (Manilo 2014). The increased spread of alien species, to some extent, is related to anthropogenic euthrophication of the sea.

The increase in the diversity of the fish fauna of the Black Sea due to economic activity is also related to attempts of intentional acclimatisation of valuable fish species (so-iuy mullet Planiliza haematocheila) and, possibly, to accidental introduction with mariculture (gilthead bream Sparus aurata and Korean rockfish Sebastes schlegelii).

Nonetheless, the current state of the fish fauna of the Black Sea within waters of Ukraine, as well as its changes due to the above processes, have been little studied. Issues related to assessment of the state and changes in diversity of marine fauna under the influence of natural and anthropogenic factors, including introduction of alien species, are extremely important (Aleksandrov et al. 2007, 2013).

A significant contribution to the study of fishes of Crimea were made by A.R. Boltachev and Ye.P. Karpova, researchers of A.O. Kovalevsky Institute of Biology of Southern Seas NAS of Ukraine, who have monitored the regions fish fauna for many years. The results of their studies are presented in numerous scientific articles and popular science issues (Boltachev et al. 1999, 2000, Boltachev & Karpova, 2012, 2017 and others).

In one of their works (Boltachev & Karpova 2014), these researchers carried out a faunal revision of all alien fish species of the Black Sea for the period 1998-2013. They indicate 25 species, among which 21 were found in the Black Sea waters of Crimea, although the ratio of species belonging to different ecological groups and having different vectors of introduction has remained unknown. In recent years, several other species have been found in this area.

The aim of the present work is to generalise data and analyse the materials on the description and further distribution of alien fish species in the Black Sea waters of the Crimean Peninsula for the past 50 years.



Material and methods

Coastal waters of Crimea are analysed within boundaries of the Black Sea from the northern coast of the Tarkhankut Peninsula (Yarylhats'ka Bay) to the Sea of Azov, including the Kerch Strait.

The systemtics and nomenclature of fishes in this work are presented according to their validity by the current data of Fish Base (Froese & Pauly 2020). More than 90 literature sources were used to compile the list of species and species descriptions.

Based on the level of the occurrence, all recently introduced species of marine waters of Crimea are grouped into three categories: regular, sporadic, and casual (Boltachev & Karpova 2014). These species represent three ecological groups: benthic, bentho-pelagic, and pelagic (a more detailed ecological classification, in our opinion, whould be impractical).

Most of recently introduces fishes in waters of Crimea €к except for Planiliza haematocheila (Temminck et Schlegel, 1845), Sebastes schlegelii Hilgendorf, 1880, Tridentiger trigonocephalus Gill, 1859 and Heniochus acuminatus (Linnaeus, 1758), which appeared due to anthropogenic factors -- represent the Antlantic-Mediterranean complex. The Indo-West Pacific Sphyraena pinguis Gunther, 1874 and Lagocephalus sceleratus (Gmelin, 1789) have already became part of the fish fauna of the Mediterranean Sea and are considered as elements of this complex. Accordingly, in this publication, we consider data on invasive species in the light of the Atlantic-Mediterranean complex.

Two species -- Kolombatovics goby Chromogobius zebratus (Kolombatovic, 1891) and Steinitzs goby Gammogobius steinitzi Bath, 1971 -- are considered as recent invaders, although the time of their appearance in waters of the Black Sea (of Crimea) is unknown.

The full list of fishes also includes species the distribution of which is not restricted to the Atlantic Ocean and which have other type of geographic range, e.g. the circumglobal Xiphias gladius Linnaeus, 1758 (distributed in tropical, subtropical, and temperate waters of all oceans) and others.

Ecologically plastic freshwater species that disperse into estuaries (Lepomis gibbosus Linnaeus, 1758, Gambusia holbrooki Girard, 1859 and others) are not considered in this work, so neither are species of the Ponto-Caspian faunal complex.

The paper includes data on the presence of specimens of introduced species in the fish collection of NMNH NAS Ukraine (No.) and on their meristic characters (brief description), which were collected by the author and researchers of other institutions during expeditions to the Crimean coast.

The special terminology currently accepted by the Convention on Biological Diversity (Carlton 1996) is as follows:

native area or donor area is the region from which the species spreads, recipient area is the area to which the species spreads;

ways of dispersal of alien species called vectors can be natural or anthropogenic;

pathways are ways through which alien species spread to new areas; such pathways are called invasive corridors if dispersal takes place systematically;

a species that appeared in a recipient area and founded an independent breeding population is called a non-native, non-indigenous, alien, exotic, or introduced species.

Results and discussion

The fish fauna of the Black Sea including freshwater species comprises not less than 263 species (Boltachev & Karpova 2017). These species belong to either the Ponto-Caspian or the Atlantic-Mediterranean faunal complex. Based on the generalised literature data, 158 fish species of the Atlantic- Mediterranean complex belonging to 107 genera and 60 families have been recorded in the Black Sea since K.F. Kesslers work was published (Kessler 1877). Earlier, many of them had been recorded beyond waters of Ukraine (41 species of 35 genera of 28 families). For instance, in waters of Turkey such species had been found as Hexanchus griseus (Bonnaterre, 1788); Mustelus asterias Cloquet, 1821; Squalus blainville (Risso, 1927); Squatina squatina (Linnaeus, 1758); Gymnura altavela (Linnaeus, 1758); Merluccius merluccius (Linnaeus, 1758); Lophius budegassa Spinola, 1807, Chelidonich- thys cuculus (Linnaeus, 1758), Lichia amia (Linnaeus, 1758), Mullus surmuletus Linnaeus, 1758; Symphodus bailloni Valenciennes, 1839; Parablennius ga’|orugine (Linnaeus, 1758); Auxis rochei (Risso, 1810); Arnoglossus laterna (Walbaum, 1792) and others. In waters of Romania and Bulgaria, Sphyrna zygaena (Linnaeus, 1758); Alopias vulpinus (Bonnaterre, 1788); Diplodus vulgaris (Geoffroy St. Hilaire, 1817); Centracanthus cirrus Rafinesque, 1810; and Scomber colias Gmelin, 1789 were found. In the Black Sea waters of the Caucasus, Argyrosomus regius (Asso, 1810), Pomatoschistuspictus (Malm, 1865), and other species were recorded.

In waters of Crimea, 116 species belonging to 86 genera and 51 families were recorded for the same period; all of them represent the Atlantic-Mediterranean complex (Table 1).

Fig. 1. The ratio of alien species that have been regularly (1), sporadically (2), and casually (3) found in waters of Crimea since the 1970s

Рис. 1. Співвідношення видів-вселенців, що постійно (1), епізодично (2) і випадково (3) зустрічаються у водах Криму з 1970-х років

Since the 1970s, 31 introduced species that belong to 27 genera and 16 families have been recorded in the Black Sea waters of Crimea, of which 15 occurred regularly (48.4 %), 9 sporadically (29.0 %), and 7 casually (22.6 %) (Fig. 1). Among all fishes of waters of Crimea, they make up 26.5 % of species, 31.0 % of genera, and 31.4 % of families that belong to the Atlantic-Mediterranean complex.

Table 1. Species composition of the Atlantic-Mediterranean fish complex of Crimea and of alien fishes (since the 1970s) with their brief characteristics

Таблиця 1. Видовий склад атлантично-середземноморського комплексу риб Криму і риб-вселенців (з 70-х років XX століття) та їх коротка характеристика



Family, species	Occurrence in waters of Crimea	Ecological group	Vector of introduction
	Reg Spo	Cas
22. Planiliza haematocheila (Temminck et				P	II
Schlegel, 1845)** XIV. Atherinidae
23. Atherina boyeri Risso, 1810	+			P
24. Atherina hepsetus (Linnaeus, 1758) XV. Belonidae	+			P
25. Belone belone (Linnaeus, 1758) XVI. Zeidae	+			P
26. Zeus faber Linnaeus, 1758 XVII. Gasterosteidae			+	P
Gasterosteus aculeatus Linnaeus, 1758 XVIII. Syngnathidae Hippocampus hippocampus (Linnaeus, 1758)	+			BP
	+			BP
29. Nerophis ophidion (Linnaeus, 1758)	+			BP
30. Syngnathus abaster Risso, 1827	+			BP
31. Syngnathus acus Linnaeus, 1758		+		BP	M/BW
32. Syngnathus tenuirostris Rathke, 1837	+			BP
33. Syngnathus typhle Linnaeus, 1758	+			BP
34. Syngnathus variegatus Pallas, 1814 XIX. Dactylopteridae	+			BP
35. Dactylopterus volitans (Linnaeus, 1758) XX. Scorpaenidae			+	B	M/BW
36. Scorpaena porcus Linnaeus, 1758	+			B
37. Sebastes schlegelii Hilgendorf, 1880 XXI. Triglidae		+		BP	UI
38. Chelidonichthys lucernu (Linnaeus, 1758) XXII. Moronidae		+		B
39. Dicentrarchus labrax (Linnaeus, 1758) XXIII. Serranidae		+		P
40. Serranus scriba (Linnaeus, 1758) XXIV. Pomatomidae	+			BP
41. Pomatomus saltatrix (Linnaeus, 1766) XXV. Carangidae	+			P
42. Trachurus mediterraneus (Steindachner, 1868)	+			P
43. Trachurus trachurus (Linnaeus, 1758) XXVI. Sparidae		+		P
44. Boops boops (Linnaeus, 1758)		+		BP	M
45. Dentex dentex (Linnaeus, 1758)			+	BP	M
46. Diplodus annularis (Linnaeus, 1758)	+			BP
47. Diplodus puntazzo (Cetti, 1784)		+		BP
48. Diplodus sargus (Linnaeus, 1758)			+	BP
49. Lithognathus mormyrus (Linnaeus, 1758)**		+		BP	M
50. Pagellus erythrinus (Linnaeus, 1758)			+	BP
51. Sarpa salpa (Linnaeus, 1758)	+			P	M
52. Sparus aurata Linnaeus, 1758 XXVII. Centracanthidae	+			BP	M/UI
53. Spicara flexuosa Rafinesque, 1810	+			P
54. Spicara maena (Linnaeus, 1758) XXVIII. Sciaenidae	+			P
55. Sciaena umbra Linnaeus, 1758	+			BP
56. Umbrina cirrosa (Linnaeus, 1758) XXIX. Mullidae		+		BP
57. Mullus barbatus Linnaeus, 1758	+			BP
XXX. Chaetodontidae
58. Heniochus acuminatus (Linnaeus, 1758) XXXI. Pomacentridae			+	BP	BW
59. Chromis chromis (Linnaeus, 1758)	+			BP
60. Ctenolabrus rupestris (Linnaeus, 1758)		+	BP
61. Labrus viridis Linnaeus, 1758		+	BP
62. Symphodus cinereus (Bonnatterre, 1788)	+		BP
63. Symphodus ocellatus (Linnaeus, 1758)	+		BP
64. Symphodus roissali (Risso, 1810)	+		BP
65. Symphodus rostratus (Bloch, 1791)		+	BP
66. Symphodus tinca (Linnaeus, 1758)	+		BP
XXXIII. Ammodytidae
67. Gymnammodytes cicerelus (Rafinesque, 1810)	+		BP
XXXIV. Trachinidae
68. Trachinus draco Linnaeus, 1758	+		B
XXXV. Uranoscopidae
69. Uranoscopus scaber Linnaeus, 1758	+		B
XXXVI. Tripterygiidae
70. Tripterygion tripteronotus (Risso, 1810)		+	B
XXXVII. Blenniidae
71. Aidablennius sphynx (Valenciennes, 1836)	+		B
72. Blennius ocellaris Linnaeus, 1758		+	B
73. Coryphoblennius galerita (Linnaeus, 1758)	+		B
74. Microlipophrys adriaticus (Steindachner et		+	B
Kolombatovic, 1883)			T	JD
75. Parablennius incognitus (Bath, 1968)**	+		B	M/BW
76. Parablennius sanguinolentus (Pallas, 1814)	+		B
77. Parablennius tentacularis (Brunnich, 1768)	+		B
78. Parablennius zvonimiri (Kolombatovic, 1892)	+		B
79. Salaria pavo (Risso, 1810)		+	B
XXXVIII. Gobiesocidae
80. Apletodon dentatus (Facciola, 1887)	+		B	M
81. Diplecogaster bimaculatus (Bonnaterre, 1788)	+		B
82. Lepadogaster candolii Risso, 1810	+		B
83. Lepadogaster lepadogaster (Bonnaterre, 1788)	+		B
XXXIX. Callionymidae
84. Callionymuspusillus Delaroche, 1809	+		B
85. Callionymus risso Lesueur, 1814	+		B
XL. Gobiidae
86. Aphia minuta (Risso, 1810)	+		P
87. Chromogobius quadrivittatus (Steindachner, 1863)**	+		B	M
88. Chromogobius zebratus (Kolombatovic, 1891)***	+		B	M
89. Gammogobius steinitzi Bath, 1971***	+		B	M
90. Gobius bucchichi Steindachner, 1870	+		B
91. Gobius cobitis Pallas, 1814	+		B
92. Gobius couchi Miller & El-Tawil, 1974**	+		B	M
93. Gobius cruentatus Gmelin, 1789**	+		B	M
94. Gobius niger Linnaeus, 1758	+		B
95. Gobius paganellus Linnaeus, 1758	+		B
96. Gobius xanthocephalus Heymer et Zander, 1992**	+		B	M
97. Millerigobius macrocephalus (Kolombatovic, 1891)**	+		B	BW
98. Pomatoschistus bathi Miller, 1982**	+		B	M
99. Pomatoschistus marmoratus (Risso, 1810)	+		B
100. Pomatoschistus minutus (Pallas, 1770)	+		B
101. Zebrus zebrus (Risso, 1826)**	+		B	M
102. Zosterisessor ophiocephalus (Pallas, 1814)	+		B
XLI. Oxudercidae
103. Tridentiger trigonocephalus Gill, 1859**	+		B	EC
XXXII. Labridae XLII. Acanthuridae 104. Acanthurus monroviae Steindachner, 1876 XLIII. Sphyraenidae		+	BP	M
105. Sphyraenapinguis Gunther, 1874		+	P	M
106. Sphyraena sphyraena (Linnaeus, 1758)	+		P
XLIV. Scombridae
107. Sarda sarda (Bloch, 1793)	+		P
108. Scomber scombrus Linnaeus, 1758	+		P
109. Thunnus thynnus (Linnaeus, 1758) XLV. Xiphiidae		+	P
110. Xiphias gladius Linnaeus, 1758 XLVI. Bothidae		+	P
111. Arnoglossus kessleri Schmidt, 1915 XLVII. Pleuronectidae	+		B
112. Platichthys flesus Linnaeus, 1758 XLVIII. Scophthalmidae	+		B
113. Scophthalmus rhombus (Linnaeus, 1758) XLIX. Soleidae	+		B	M
114. Pegusa nasuta (Pallas 1814) L. Balistidae	+		B
115. Balistes capriscus Gmelin, 1789 LI. Tetraodontidae		+	BP
116. Lagocephalus sceleratus (Gmelin, 1789)		+	BP	M

Note. Introduced species that have appeared since the 1970s are given in bold. Occurrence of species in waters of Crimea: Reg -- regular, Spo -- sporadic, Cas -- casual. Ecological groups of fishes: P -- pelagic, BP -- bentho-pelagic, B -- benthic. Vector of introduction: M -- natural expansion (mediterranisation); BW -- by ballast waters; M/BW -- unknown, either mediterranisation or by ballast waters; M/UI -- unknown, either mediterranisation or unintentional introduction; UI -- unintentional introduction; II -- intentional introduction; EC -- escape from captivity; ** -- species that have acclimatised in waters of Crimea; *** -- unknown time of introduction.

Brief information is given below on introduced species that have occured regularly, sporadically, or casually in the Black Sea waters of Crimea since the 1970s.

Species that occur regularly in waters of Crimea

Order Mugiliformes

Family Mugilidae Bonaparte, 1831 Genus Planiliza Whitley, 1945

Planiliza haematocheila (Temminck et Schlegel, 1845) -- Redlip mullet

Synonyms: Mugil haematocheilus Temminck & Schlegel, 1845; Mugil soiuy Basilewsky, 1855; Liza menada Tanaka, 1916.

Material (in the fish collection of NMNH NASU): Sea of Azov -- No. 3292, 5711,5786, 6285, 6483, 6489, 6502, 6610, 6625, 6642, 8074, 8075, 8076, 9605, 10223; Danube Delta -- No. 8429).

Brief description. D IV, D21 8-9, A III 8-10, P 14-17, Squ 36-46 (our data).

Distribution. The species' native range covers coastal waters of the Sea of Japan and the Yellow Sea. It has acclimatised in the Azov-Black Sea Basin and widespread in seas of the Mediterranean Basin (Streftaris & Zenetos 2006). Currently occurs along the entire seacoast of Ukraine, including Crimea.

Vector of introduction. Intentional introduction to the Azov-Black Sea Basin since the 1970s with a formation of a breeding population. The species has completely acclimatised and become commercially important. Accidental escape to natural water bodies from isolated cultivating facilities.

Order Perciformes

Family Sparidae Bonaparte, 1832

Genus Sarpa Bonaparte, 1831

Sarpa salpa (Linnaeus, 1758) -- Salema porgy

Synonyms: Sparus salpa Linnaeus, 1758; Box salpa (Linnaeus, 1758).

Material (in the fish collection of NMNH NASU): No. 6526, 8168.

Brief description. D XI-XII 14-17; A III 13-15; P I 15; У I 5; l? 71-80; sp.br. 6-7 on the upper and 12-14 on the lower parts of the firt gill arch (our data).

Distribution. The species' range covers the continental shelf of the eastern Atlantic Ocean from the North Sea to South Africa, as well as the Mediterranean Sea (Svetovidov 1964). Single records were known in the Black Sea off the shore of Turkey, Georgia (Batumi), Bulgaria (Varna Bay), and Romania (Constanta) (Vasileva 2007). In waters of Ukraine, it was first recorded near Crimea in Bal- aklava Bay (September 1999) and it has reached a relatively high abundance near southwest Crimea; several specimens were caught off the southern coast of the peninsula near Cape Martyan and Cape Ayu-Dag (Boltachev & Yurachno 2002; Boltachev & Karpova 2012). Since 1995, the species has been recorded annually in Tendra Bay, Yahorlyk Bay, and in the coastal marine zone of Kinburn Spit and Tendra Island (Tkachenko 2012).

Vector of introduction. Natural spread through the Bosphorus from seas of the Mediterranean Basin (mediterranisation) with further dispersal along the coast of the Black Sea. In coastal waters and in coves of Sevastopol Bay, the species occurs regularly in flocks of 100 and more specimens. It is caught by commercial industrial seines and gill nets (Boltachev & Karpova 2014).

Genus Sparus Linnaeus, 1758

Sparus aurata Linnaeus, 1758 -- Gilthead seabream

Synonyms: Aurata aurata (Linnaeus, 1758); Chrysophrys aurata (Linnaeus, 1758); Pagrus auratus (Linnaeus, 1758);

Chrysophrys aurathus (Linnaeus, 1758); Sparus auratus Linnaeus, 1758.

Material (in the fish collection of NMNH NASU): No. 8740, 8741, 10345.

Brief description. D XI 12-14, A III 11-12, P 15, У I 5, l.l. 73-85, sp.br. 4-6 on the upper and 7-8 on the lower parts of the first gill arch (our data).

Distribution. The species is distributed in the eastern Atlantic Ocean from Britain to Cap-Vert, common in most seas of the Mediterranean Basin (Fishes of... 1986a; Marine Species… 2000). In the Black Sea, records were reported from coastal waters of Turkey, Bulgaria, Romania, and Georgia (Vasileva 2007). In waters of Ukraine, the species was first found near the entrance of Balaklava Bay in August 1999 and it was regularly recorded in the coastal zone of Sevastopol (Boltachev & Yurachno 2002; Boltachev et al. 2009). Since 2004, 10 and more specimens have been regularly recorded near the Danube Delta, Kinburn Spit, as well as in Tendra and Yahorlyk Bays and in the Dnipro-Bug Estuary (Tkachenko 2012; Manilo & Redinov 2019). The species was also found in the southern part of the Sea of Azov (Milovanov & Dubovik 2013).

Vector of introduction. Natural spread through the Bosphorus from seas of the Mediterranean Basin (mediterranisation). The appearance of marine farms in Turkey that specialise on the cultivation of this species allows to consider possible escapes of the species from these facilities to the Black Sea.

Family Blenniidae Rafinesque, 1810

Genus Parablennius Ribeiro, 1915

Parablennius incognitus (Bath, 1968) -- Mystery blenny

Synonyms: Blennius incognitus Bath, 1968; Blennius ponticus incognitus Bath, 1968.

Material (in the fish collection of NMNH NASU): No. 7259.

Brief description. D XII 17; A II 18-19; P 13-14; У I 2-3 (our data).

Distribution. The species' range covers the eastern Atlantic Ocean from the Azores and Canary Islands to the shores of Cameroon, as well the Iberian Peninsula and most seas of the Mediterranean

Basin (Fishes of... 1986b). The first record of the species in the Black Sea was reported off the shores of Abkhazia in 2001 (Bogorodskii 2006) and, about at the same time, near Turkey and in the Kerch Strait (Vasileva 2007; Keskin 2010). It is possible that Pincognitus had appeared in the Black Sea notably earlier. In waters of Ukraine, the species was first recorded near Sevastopol in the summer of 2002, wheares in 2003 it was often found in open rocky areas of the shore from Sevastopol Bay to Cape Fiolent (Boltachev et al. 2009). According to data from 2013 (Boltachev & Karpova 2017), the species has spread along the entire southern coast of Crimea to Cape Opuk having an abundance as high as native blenny species.

Vector of introduction. Introduction of the species to the Black Sea could take place naturally from the Marmara Sea (mediterranisation), although almost simultaneous catches in several remote locations might indicate human-mediated appearance with ballast waters or on the bottoms of ships.

Family Gobiesocidae Bleeker, 1859

Genus Apletodon Briggs, 1955

Apletodon dentatus (FacciolE, 1887) -- Small-headed clingfish

Synonyms: Lepadogaster bacesqui Murgoci, 1940; Apletodon dentatus dentatus (Facciola, 1887).

Material (in the fish collection of NMNH NASU): absent.

Brief description. D 5-6; A 5-7; P 21-24 (Vasileva 2007, Black Sea). D 7-8; A 6-8; P 19 (Karpova et al. 2017, Black Sea, Crimea).

Distribution. The species' range covers waters of the eastern Atlantic Ocean from the southwest coast of the Scandinavian Peninsula to Spain; it is common in the Mediterranean Basin. In the Black Sea, a small number of records of the species are known from a narrow coastal zone of Romania; one specimen was caught in waters of Turkey near Cape Sinop in May 2000 (Fishes of... 1986b; Mediterranee... 1987; Bat et al. 2006). In waters of Ukraine, the species was recorded only near Sevastopol (in coves and along the open coast) and near the Tarkhankut Peninsula. Records of the small-headed clingfish in the Black Sea are related to habitats with outcrops of porous limestones (Karpova et al. 2017).

Vector of introduction. Natural spread through the Bosphorus from seas of the Mediterranean Basin (mediterranisation).

Order Gobiiformes

Family Gobiidae Fleming, 1822

Genus Chromogobius de Buen, 1930

Chromogobius quadrivittatus (Steindachner, 1863) -- Chestnut goby

Synonyms: Gobius depressus quadrivittata Steindachner, 1863; Relictogobius kryzhanovskii Ptchelina, 1939; Chromogobius kryzanowskii (Ptchelina, 1939).

Material (in the fish collection of NMNH NASU): No. 2771, 6185.

Brief description. D1 VI, D2 I 10, A I 9, P 17 (Kovtun 2013, Black Sea, underwater caves of the Tarkhankut Peninsula). D1 VI, D2 I 10, A I 9-10, P 17 (our data, Black Sea coast of the Caucasus).

Distribution. The species' range covers coastal waters of the northern and eastern parts of the Mediterranean Sea (Adib 2005), as well as the Marmara, Aegean (Bilecenoglu et al. 2014), and Black Seas. A rare and non-abundant species in all localities. In had been known earlier in the Black Sea near the shore of the Caucasus (Pchelina 1939; Pinchuk 1987), where it has entirely disappeared (Pashkov et al. 2013), and in Varna Bay (Georgiev 1961). A single specimen found during fish kill near Odessa was reported by A.K. Vinogradov and S.А. Khutornoy (2013), but the specimen was lost and only a photo was published. In waters of Ukraine, the species was first recorded in underwater karst caves of Cape Tarkhankut (Kovtun 2013). Several specimens, including juveniles, were found in Martynova Cove (Sevastopol) in 2015 (Boltachev & Karpova 2016) and in Kozacha Cove in 2016 (Boltachev & Karpova 2017), which, in our opinion, can be considered as current further dispersal and acclimatisation of the species in waters of Crimea. According to the latest data (O.A. Kovtuns personal report), this species was found in underwater caves of Bulgaria north of Varna Bay, close to the border with Romania.

Vector of introduction. Natural spread through the Bosphorus from seas of the Mediterranean Basin (mediterranisation).

Chromogobius zebratus Kolombatovic, 1891 -- Kolombatovics goby Synonyms: Gobius depressus var. zebratus Kolombatovic, 1891; Chromogobius zebratus zebratus (Kolombatovic, 1891);

Gobius depressus zebratus Kolombatovic, 1891.

Material (in the fish collection of NMNH NASU): absent.

Brief description. D VI, D I 11, A I 10, P 14, Squ 46. (Kovtun & Karpova 2014, Black Sea, underwater caves of the Tarkhankut Peninsula).

Distribution. The species' range covers the northwest and eastern parts of the Mediterranean Sea from the Strait of Gibraltar to Israel. Near the shores of Turkey, Ch. zebratus was first found in the Aegean Sea only in 2008 (Engin & Dalgic 2008). The species' abundance is low. It is a cryptobenthic and quite rare species. In waters of Ukraine, it was first recorded in underwster karst caves of Cape Tarkhankut (Kovtun & Karpova 2014).

Vector of introduction. Natural spread through the Bosphorus from seas of the Mediterranean Basin (mediterranisation). The time of its appearance in the Black Sea is unknown.

Genus Gammogobius Bath, 1971

Gammogobius steinitzi Bath, 1971 -- Steinitz's goby Synonyms: absent.

Material (in the fish collection of NMNH NASU): No. 9261.

Brief description. D VI, D2 I 8-9, A I 7-9, P 15-17, У I 5, Squ 31-32 (Crimea, underwater caves of Cape Tarkhankut; our data).

Distribution. The species is known from several localities of the northern part of the Mediterranean Sea: near the coast of France (Dufour et al. 2007), Ibiza, (Scsepka & Ahnelt 1999), in the north of the Tyrrhenian Sea near Giglio Island, Italy (Ahnelt et al. 1998), in the north of the Adriatic Sea near Krk Island (Kovacic 1999), and near Cretea (Kovacic et al. 2011). In the Black Sea, the species in known only in waters of Ukraine from underwater karst caves of the Tarkhankur Peninsula (Malyi Atlesh tract) (Kovtun 2012; Kovtun & Manilo, 2013).

Vector of introduction. Natural spread through the Bosphorus from seas of the Mediterranean Basin (mediterranisation). The time of its appearance in the Black Sea is unknown.

Genus Gobius Linnaeus, 1758

Gobius couchi Miller et El-Tawil, 1974 -- Couch's goby Synonyms: absent.

Material (in the fish collection of NMNH NASU): absent.

Brief description. D (V) VI (VII), DI (11) 12-13, A I (10) 11-12, P 16-17, Squ 36-44 (Karpova & Boltachev 2018).

Distribution. A quite rare Atlantic-Mediterranean species. It was recorded near the shores of Great Britain and Ireland, as well as in the northern part of the Mediterranean Sea and in the Aegean Sea (Miller & El-Tawin 1974; Minchin 1988; Costello 1992; Kovacic et al. 2013). The species did not occur in the Black Sea until recently, when it was found in Kozacha and Karantinna Coves of Sevastopol Bay (Karpova & Boltachev 2018). According to these researchers, the species has fully adapted to conditions of the southwest coast of Crimea.

Vector of introduction. Natural spread through the Bosphorus from seas of the Mediterranean Basin (mediterranisation).

Gobius cruentatus Gmelin, 1789 -- Red-mouthed goby

Synonyms: Gobius rubens Rafinesque, 1810; Gobius strictus Fage, 1907.

Material (in the fish collection of NMNH NASU): No. 7253.

Brief description. D VI, DI 14, A I 13, P 20, Squ 53 (our data).

Distribution. The native range of the species includes waters of the eastern Atlantic Ocean from the southwest of Ireland to Senegal, as well as the western and northern parts of the Mediterranean Sea (Miller 1986; Kovacic 2005; Golani et al 2006). In the Black Sea, it was found off the coast of Turkey (Engin et al. 2007). Near the shores of Ukraine, the species is known in Crimea from coastal waters near Sevastopol (Boltachev et al. 2009). Since 2009, the species has occurred regularly in the coastal zone and in some coves of Sevastopol Bay.

Vector of introduction. Natural spread through the Bosphorus from seas of the Mediterranean Basin (mediterranisation) with further acclimatisation off the coast of southwest Crimea.

Gobius xanthocephalus Heimer et Zander, 1992 -- Yellow-headed goby

Synonyms: absent.

Material (in the fish collection of NMNH NASU): No. 7254.

Brief description. D VI, DI 14-16, A I 13-14, У 12, Squ 44-45 (our data).

Distribution. The species' range covers the eastern Atlantic Ocean along the shores of Portugal (Almeida & Arruda 1998) and the Canary Islands (Wirtz & Herrera 1995). It is a common species in the Mediterranean Sea off the coast of France (Heimer & Zander 1992). In the Black Sea, the species is rare and its records are known from near the shores of Abkhazia (Vasileva & Bogorodskii 2004) and from Crimea near Sevastopol (Boltachev et al. 2009) and Cape Tarkhankut (Karpova & Saksahanskyy 2011). The yellow-headed goby is currently quite common but non-abundant in the coastal zone of southwest Crimea from Cape Tovstyi to Cape Fiolent and near Cape Tarkhankut.

Vector of introduction. Natural spread through the Bosphorus from seas of the Mediterranean Basin (mediterranisation) with further acclimatisation off the coast of southwest Crimea and Abkhazia.

Genus Millerigobius Bath, 1973

Millerigobius macrocephalus (Kolombatovic, 1891) -- Large-headed goby

Synonyms: Gobius macrocephalus Kolombatovic, 1891.

Material (in the fish collection of NMNH NASU): No. 8894.

Brief description. D VI, D21 11, A I 10, P 14-16, Squ 29-31 (our data).

Distribution. The species was known as an endemic of the Aegean and Adriatic Seas (Miller 1986; Golani et al. 2006; Kovacic 2008) and in the western part of the Mediterranean Sea near Ibiza Island (Fischer et al. 2007). It had not been recorded in the Black Sea earlier. In waters of Ukraine, the species' population comprising specimens of different age was first recorded in 2009 in the lower part of Sevastopol Bay (Boltachev et al. 2010). An independent population has formed here.

Vector of introduction. The species could have appeared in the Black Sea with ballast waters. The vector of its individual spread currently needs further studies (Boltachev et al. 2010).

Genus Pomatoschistus Gill, 1863

Pomatoschistus bathi Miller, 1982 -- Bath's goby

Synonyms: absent.

Material (in the fish collection of NMNH NASU): No. 7913.

Brief description. D VI, D2 I 7-9, A I 8-9, P 15-17, Squ 34-35 (Kozacha Cove, Black Sea; our data).

Distribution. The species' native range covers the Mediterranean Basin. In the Black Sea, the species occurs near the shores of the Caucasus (Vasileva & Bogorodskii 2004; Vasileva 2007) and Bulgaria (Vassilev et al. 2012). In marine waters of Ukraine, the species has been recorded since the early 2000s in Sevastopol Bay and along the southern shore of Crimea from Cape Sarych to Cape Tovstyi (Boltachev & Karpova 2010a). Bath's goby is currently an abundant species in Sevastopol Bay, Lake Donuzlav, near Cape Tarkhankut (Eremeev et al. 2012), in Karkinit Bay (Prishchepa et al. 2018), and in waters of Kara-Dag Nature Reserve. Based on the relatively frequent occurences of groups of various sizes, the species has formed an independent breeding population in the coastal zone of Crimea. The species increases its abundance and distribution range along the Black Sea coast.

Vector of introduction. Natural spread through the Bosphorus from seas of the Mediterranean Basin (mediterranisation) with further naturalisation off the shore of Crimea, the Caucasus, and Bulgaria. The spread of Bath's goby to the Black Sea is a typical example of mediterranisation with subsequent complete and successful naturalisation.

Genus Zebrus Gill, 1859

Zebrus zebrus (Risso, 1827) -- Zebra goby

Synonyms: Gobius zebrus Risso, 1827.

Material (in the fish collection of NMNH NASU): absent.

Brief description. Di VI (V-VI), D2 I 10-11, A I 9 (7-10), P 17 (16-18), Squ 29-38, Vert. 26-27 (Miller 1986).

Distribution. The species is distributed in the Mediterranean Sea except for the offshore waters of northern Africa. In the eastern Atlantic Ocean, the zebra goby occurs off the shore of Spain in the south of the Iberian Peninsula. In 2007, a mature specimen was caught in the Black Sea off the shore of Turkey near Cape Jason (Kovacic & Engin 2009). In 2009, it was recorded in Sevastopol Bay on mussel collectors (Boltachev et al. 2010) together with Millerigobius macrocephalus. In the following years, the species was found in Striletska and Martynova Coves of Sevastopol Bay, which allows concluding on the species' acclimatisation in Crimea (Manilo et al. 2013).

Vector of introduction. Natural spread through the Bosphorus from seas of the Mediterranean Basin (mediterranisation) with further naturalisation near the shores of Turkey and southwest Crimea.

Family Oxudercidae Gunther, 1861

Genus Tridentiger Gill, 1859

Tridentiger trigonocephalus Gill, 1859 -- Chameleon goby

Synonyms: Triaenophorus trigonocephalus Gill, 1858; Triaenophorichthys trigonocephalus Gill, 1859; Tridentiger bifasciatus Steindachner, 1881.

Material (in the fish collection of NMNH NASU): No. 2464, 7255.

Brief description. D1VI, D2111, A 111, P 19, V10, Squ 51 (Sevastopol, mouth of the Chorna river, our data).

Distribution. The species' native range covers coastal and estuary waters of the Sea of Japan, the Yellow Sea, and the South China Sea (Lindberg & Krasyukova 1975), wherefrom it spread with ballast waters of commercial vessels, as well as due to the large-scale export of the Pacific oyster from cultivation farms of Japan with goby eggs attached to the shells. The species appeared in waters of California (USA) and Australia, where it completely naturalised (Global Invasive… 2007). In the Mediterranean Basin, the species is known by a single specimen recorded near the coast of Israel in the harbour of the port of Ashdod (Goren et al. 2009). In waters of Ukraine, it was first recorded in Sevastopol Bay in 2006 (Boltachev et al. 2007). It was concluded in 2009 that the species have completely acclimatised in waters of Sevastopol Bay (Boltachev & Karpova 2010b).

Vector of introduction. The most probable vector of introduction of the species is escape from captivity. In early 1980, several dozens of specimens were brought from Posyet Bay (Far East) to the Sevastopol Aquarium for decorative keeping, but their colouration was not spectacular enough for demonstration and they were released into Sevastopol Bay, where they probably formed a local population (Boltachev & Karpova 2010).

Species that occur sporadically in waters of Crimea

Order Clupeiformes Family Clupeidae Cuvier, 1816

Genus Sardina Antipa, 1904

Sardina pilchardus (Walbaum, 1792) -- Pilchard sardine

Synonyms: Clupea harenguspilchardus Walbaum, 1792; Alosa pilchardus (Walbaum, 1792); Clupeapilchardus Walbaum, 1792; Clupea pilchardus Bloch, 1795; Sardina dobrogica Antipa, 1904.

Material (in the fish collection of NMNH NASU): No. 7641, 9267, 9269.

Brief description. D 13-21; A 12-23; sp.br. 78-90 (our data).

Distribution. The species' range covers the eastern Atlantic Ocean from the North Sea and Iceland to Senegal, as well as the Mediterranean and Black Seas. In the latter, the species occurs along the coasts, but mostly in the Bosphorus area. In small numbers, it is also caught by seines in the coastal zone and coves of Sevastopol, in the Kerch Strait during spring and autumn migrations of pelagic fishes, while in winter it occurs off the shore and observed in catches of trawlers along the southers coast of Crimea. Since the 2000s, the species has been sporadically recorded in cathes of trawlers on the southern continental shelf of Crimea in autumn and early winter. It is rare in the coastal zone (Boltachev et al. 2014).

Vector of introduction. Episodic migrations to the Black Sea from seas of the Mediterranean Basin through the Bosphorus (mediterranisation).

Genus Sardinella Valenciennes, 1847

Sardinella aurita (Valenciennes, 1847) -- Round sardinella

Synonyms: Clupea allecia Rafinesque, 1810; Alosa senegalensis Bennett, 1831; Sardinella anchovia Valenciennes, 1847;

Sardinia pseudohispanica Poey, 1860; Sardinella euxina Antipa, 1906.

Material (in the fish collection of NMNH NASU): absent.

Brief description. D III-IV 14-16; A 13-15; Р I 12; У I 8; sp.br. 201-208, 31-36 abdominal spikes (Movchan 2011).

Distribution. Warm waters of the western and eastern Atlantic Ocean, the Mediterranean, Aegean, and Marmara Seas (Fishes of...1986a; Vasileva 2007). Rarely occurs near the shores of Crimea and in the Black Sea in general, where records were reported from near Burgas, Constanta, and Batumi (Svetovidov 1964). Single specimens were recorded off the coast of Crimea near Kara-Dag in 1981 and 1988 (Salekhova & Kostenko 1989) and in coves of Sevastopol Bay: in Balaklava in October 1998 (Boltachev et al. 2000) and in Striletska in July 2008 (Boltachev et al. 2010).

Vector of introduction. Episodic migrations during warm periods to the Black Sea from the Mediterranean Basin through the Bosphorus (mediterranisation).

Order Mugiliformes

Family Mugilidae Bonaparte, 1831

Genus Chelon Risso, 1793

Chelon labrosus (Risso, 1827) -- Thicklip grey mullet

Synonyms: Mugil labrosus Risso, 1827; Crenimugil labrosus(Risso, 1827); Mugil chelo Cuvier, 1829; Mugil chelon Cuvier,

1829; Mugil curtus Yarrell, 1836; Mugil buosega Nardo, 1847.

Material (in the fish collection of NMNH NASU): absent.

Brief description. D1 III-IV, D2 I 8 (9), A III 3 (8) 9, P 16 (17), sp.br. 35-76, Squ 41-47 (Movchan 2011).

Distribution. The species' range covers coastal waters of the eastern Atlantic Ocean from the south of Norway to the islands of Cap-Vert and of the northern Atlantic Ocean from Europe to the south of Iceland. The species is abundant in seas of the Mediterranean Basin (Froese & Pauly 2020). It was first recorded in Balaklava Cove in October 1999 and it occurred regularly in the following ten years near the southwest coast of Crimea from Cape Khersones to Cape Aya (Boltachev & Yurachno 2002; Boltachev et al. 2009). Since the early 2010s, the species has been rarely recorded, which could be related to either the complexity of its catching or the cyclic appearance of the species near the coast of Crimea. The species occurs in mixed groups with native mullet species (Boltachev et al. 2009).

Vector of introduction. Natural spread from seas of the Mediterranean Basin through the Bosphorus (mediterranisation). Annual feeding migrations to the shores of Crimea from the seas of the Mediterranean Basin.

Chelon ramada (Risso, 1827) -- Thinlip mullet

Synonyms: Mugil ramada Risso, 1827; Liza ramada (Risso, 1827); Mugil capito Cuvier, 1829; Mugil caustelus Nardo, 1847; Mugil petherici Gunther, 1861; Liza alosoides Fowler, 1903.

Material (in the fish collection of NMNH NASU): absent.

Brief description. Di IV, D I 8-9, A III (8) 9, P 16, Squ 44-46 (Movchan 2011).

Distribution. The species inhabits seas of the Mediterranean Basin and the eastern Atlantic Ocean from Scandinavia and the southern part of the Baltic Sea to Senegal and the islands of Cap-Vert. It is rare in the Black Sea and most of its records are known from the coastal zone of Turkey, Romania, and Bulgaria (Harrison 2003). The first record of this species off the coast of Crimea was reported from near Sevastopol in 1930, but it was found again only in October 2006. In October 2012, the species was found for the third time in catches near Balaklava (Boltachev et al. 2009).

Vector of introduction. Natural spread through the Bosphorus from seas of the Mediterranean Basin (mediterranisation). Annual feeding migrations to the Black Sea.

Order Gasterosteiformes

Family Syngnathidae Bonaparte, 1831

Genus Syngnathus Linnaeus, 1758

Syngnathus acus Linnaeus, 1758 -- Greater pipefish

Synonyms: Syngnathus acus (Linnaeus, 1758); Typhle heptagonus Rafinesque, 1810; Syngnathus rubescens Risso, 1810;

Syngnathus brachyrhynchus Kaup, 1856; Syngnathus delaland Kaup, 1856.

Material (in the fish collection of NMNH NASU): No. 4861, 4862, 7258.

Brief description. D 31-34, A 3-4, P 13, 16-18 trunk vertebrae, 36-43 caudal rings, 8-9 subdorsal rings (our data).

Distribution. The species' native range covers the eastern Atlantic Ocean from the coasts of Norway, Faroes, and the British Isles to Western Sahara, including the Mediterranean and Aegean Seas, as well as the area from N...