Aquatic Invasions (2012) Volume 7, Issue 3: 425–431 doi: http://dx.doi.org/10.3391/ai.2012.7.3.013 © 2012 The Author(s). Journal compilation © 2012 REABIC

Open Access

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Short Communication

New record of the planktonic copepod Oithona davisae Ferrari and Orsi in the Black Sea with notes on the identity of “Oithona brevicornis”

Alexandra Temnykh1* and Shuhei Nishida2

1 Institute of Biology of the Southern Seas, 2, Nakhimov Ave., Sevastopol 99011, Ukraine 2 Atmosphere and Ocean Research Institute, University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa 277-8564, Japan

E-mail: atemnykh@yandex.ua (AT), nishida@aori.u-tokyo.ac.jp (SN)

*Corresponding author

Received: 1 December 2011 / Accepted: 10 February 2012 / Published online: 27 February 2012

Abstract

Specimens of small (< 1 mm) cyclopoid copepods of the genus Oithona were collected from Sevastopol Bay and an offshore area of the Black Sea. On the basis of a combination of characteristics such as those in the maxillule and the genital double-somite, the specimens were identified as O. davisae Ferrari and Orsi, 1984. The identity of “O. brevicornis” that was reported in the Black Sea and the possible origin of O. davisae in the Black Sea are discussed.

Key words: Oithona davisae, species identification, ballast water, synanthropic introduction

Introduction

Reports since 2001 outline the occurrence of the cyclopoid copepod Oithona brevicornis Giesb-recht, 1891 (see also Giesbrecht 1893 ["1892"]), in the Black Sea (Zagorodnyaya 2002; Altukhov and Gubanova 2006; Gubanova and Altukhov 2007; Selifonova et al. 2008; Selifonova 2009). The identification was based on the examination of a few morphological characters, such as the shape of the head (rounded anteriorly) and rostrum (sharply pointed) and the numbers of spines on segments 1–3 of legs 1–4 (with the formula of 1, 1, 3; 1, 1, 3; 1, 1, 3; 1, 1, 2) in the female (Zagorodnyaya 2002; Gubanova and Altukhov 2007). However, according to our recent examination of copepod specimens from the Black Sea, there is another species of Oithona that is similar to O. brevicornis with respect to the above features, but shows marked differences in some other characters. This further led us to suspect that the cyclopoid species recently recorded as new to the Black Sea may not be O. brevicornis, or include one or more species that resemble O. brevicornis. Here we describe the characteristics of the present specimens and compare them with those of O. brevicornis and other related species, and

identify the species with notes on their distributions. Possible causes for the introduction of the species into the Black Sea are also discussed.

Materials and methods

Plankton samples were collected by vertically-stratified tows of a Juday net (mouth area, 0.1 m2; mesh size, 115 µm) from depth layers of 125–65, 65–40, 40–25, 25–10, and 10–0 m in an offshore area of the Black Sea (around 44°21′N, 33°05′E; depth, 1250–1800 m) on November 12 2010. Samples were also collected by vertical tows of the same net (but with mesh size, 85 µm) from 5 m depth to the surface in Sevastopol Bay (44°37′13″N, 33°32′53″E; depth, 14 m) on 18 November 2008. Immediately after collection the samples were fixed and preserved in 4% formaldehyde/seawater solution and buffered with sodium tetraborate. Temperature and salini-ty of the sampling sites were measured with a hydrobiophysical complex “SALPA” (Vasilenko et al. 1997). In the laboratory, small adult females (< 1 mm) Oithona copepods that had a rounded anterior margin of the prosome and a sharply pointed rostrum were sorted from each sample. These specimens were put in a drop

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Figure 1. Photographs of Oithona davisae collected from the Black Sea in the present study. A, rostrum, lateral view; B, mandible, focusing on setae on the endopod (arrows); C, maxillule, focusing on long distal-most spine (arrow) on the first inner lobe and the single seta (arrowhead) on the endopod; D, genital-and next somite, lateral view, showing absence of hair-rows on the dorsal surfaces (arrows).

of 10% glycerine/distilled water on a depression slide, and total length measured from the anterior end of the prosome to the posterior end of the caudal ramus, excluding caudal setae, with a calibrated ocular micrometer, under a compound microscope. For detailed examination, appendages including the mandible, maxillule, and swimming legs, were dissected from the body trunk and examined at a magnification of ×1000 with a ×10 eyepiece and an oil-immersion objective lens (×100); the Humes and Gooding's (1964) method was applied.

Results

The water column at the sampling site in Sevastopol Bay was vertically mixed with temperature and salinity of ca.16.5°С and 18 psu, respectively. In the offshore water the upper 40

m was well mixed with temperature and salinity of ca.16.5°С and 17.5 psu. A marked thermocline existed in the 40–65 m layer, where the temperature decreased with depth to 9°С and salinity increased to 18.3 psu. The targeted Oithona specimens were found in the samples from Sevastopol Bay and from the upper 65 m of the offshore area, but they were not recorded in samples from 125–65 m.

The following characteristics were common to all the present specimens: total length ranged from 0.50 to 0.59 mm (n=20); anterior margin of prosome was rounded in lateral view and ventrally terminated in a sharply pointed rostrum (Figure 1A; see also Figure 2H); the endopod of the mandible bore 4 setae (Figure 1B, arrows; see also Figure 2I); the distal spine on the first inner lobe of the maxillule was very long, ca. 2.5 times as long as the next spine (Figure 1C, arrow; see also Figure 2J, arrow); the endopod of

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Figure 2. Character comparison between Oithona brevicornis (A-D), O. aruensis (E-G), and O. davisae (H-K). A, E, H: rostrum. B, F, I: mandible. C, G, J: maxillule; indicating distal-most spine (thin arrow) of first inner lobe, endopod (arrowhead), seta on second inner lobe (dotted arrow; absent in J) and seta on second basal segment (thick arrow; absent in J). D: genital double-somite and next somite, lateral view; indicating rows of hairs (arrows) in O. brevicornis. K: genital double-somite, lateral view. After Nishida (1985: A-D), Nishida and Ferrari (1983: E-G) and Ferrari and Orsi (1984: H-K). Not to scale.

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Table 1. Comparison of characteristics in adult females among four species and the present specimens of Oithona.

Species Oithona brevicornis Oithona wellershausi

Oithona aruensis

Oithona davisae Present specimens

Total length (mm) 0.48-0.71 0.45-0.50 0.44-0.46 0.49-0.62 0.50-0.59

Rostrum curved and sharply pointed

curved and sharply pointed

curved and sharply pointed

curved and sharply pointed curved and sharply pointed

Number of setae on endopod of maxillule

3 3 3 1 1

Distal-most spine on first inner lobe of maxillule

shorter than next spine > 2 times as long as next spine

ca. 3 times as long as next spine

ca. 2.5 times as long as next spine

ca. 2.5 times as long as next spine

Number of seta on second inner lobe of maxillule

1 0 1 0 0

Number of seta on second basal segment of maxillule

1 1 1 0 0

Hair-rows on dorsolateral surface of genital double-somite and next somite

present absent absent absent absent

Geographic distribution

Indo-West Pacific Pearl River estuary (China)

Indo-West Pacific

East Asia, California, Chile, Mediterranean

Black Sea

Fine-scale distribution outer part of enclosed bays

not available estuaries and inner part of enclosed bays

estuaries and inner part of enclosed bays

Sevastopol Bay and offshore water

References Nishida et al. (1977), Ferrari (1981: as O. spinulosa), Nishida and Ferrari (1983), Nishida (1985)

Ferrari (1981) Nishida and Ferrari (1983), Nishida (1985)

Nishida et al. (1977), Ferrari and Orsi (1984), Nishida (1985), Hirakawa (1988), Saiz et al. (2003)

This study

the maxillule bore only one seta (Figure 1C, arrowhead; see also Figure 2J, arrowhead); there were no setae on the second inner lobe and the second basal segment of the maxillule (see Figure 2J, dotted- and thick arrows); the exopod segments 1–3 of legs 1–4 bore 1, 1, 3; 1, 1, 3; 1, 1, 3; 1, 1, 2 lateral spines; there were no hair rows on the dorsolateral surface of the genital double-somite and/or the next somite (Figure 1D, arrows). The mean total length of the specimens from the Sevastopol Bay [0.568±0.018 mm (mean ±SD), n=10] was slightly larger than that of the offshore specimens (0.533±0.029 mm, n=10) (t-test, p<0.01), while there were no marked differences in other characters between the specimens from the two localities.

Table 1 compares the characteristics of the present specimens with those of the four Oithona species, namely O. brevicornis (Figure 2A–D; Nishida 1985), O. wellershausi Ferrari, 1981, O. aruensis Früchtl, 1923 (Figure 2E–G; Nishida and Ferrari 1983) and O. davisae Ferrari and Orsi, 1984 (Figure 2H–K). Characteristics such as body form (oval prosome with sharply pointed rostrum) and swimming legs (number of exopod spines on legs 1–4: 1, 1, 3; 1, 1, 3; 1, 1, 3; 1, 1, 2) are similar. In all the characteristics listed in Table 1, the present specimens correspond with O. davisae, but not with the other species. Oithona brevicornis differs from the other species in that the distal-most spine on the first inner lobe of the maxillule is much shorter than

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the next spine (much longer than the next spine in the other species: Figure 2C, G, J, thin arrows) and rows of fine hairs are present on the posterior dorsolateral surface of the genital double-somite and the anterior dorsolateral surface of the next somite (such rows are absent in the other species: Figure 2D, K, arrows). Oithona davisae differs from O. aruensis and O. wellershausi in having only one seta on the endopod [three setae in O. aruensis (Figure 2G, J, arrowheads) and O. wellershausi (figure not shown)] and lack of a seta on the second basal segment of maxillule [one seta present in O. aruensis (Figure 2G, J, thick arrows) and O. wellershausi (figure not shown)]. Oithona davisae also lacks a seta on the second inner lobe of maxillule while it is present in O. brevicornis and O. aruensis (Figure 2C, G, J, dotted arrows). From these observations we conclude that the present Oithona specimens are O. davisae.

Discussion

Oithona davisae has been reported from the coastal waters of Japan (e.g. Nishida et al. 1977, as “O. brevicornis f. minor”; Nishida and Ferrari 1983, as “O. aruensis”; Nishida 1985; Ohtsuka et al. 2008) and Korea (Lee et al. 2001; Orui-Sakaguchi et al. 2011), with its occurrences also being reported from California, the type locality (Ferrari and Orsi 1984), Chile (Hirakawa 1988), and the northwestern Mediterranean (Nishida’s unpublished observation cited by Saiz et al. 2003). Kasyan (2010) reported the occurrence of O. davisae in the ballast water of ships that arrived at Vladivostok from Chinese coasts. With these records, it is widely accepted that O. davisae is originally endemic to the temperate coastal waters of East Asia and its occurrence in other remote regions are due to synanthropic introduction, mainly in ship’s ballast waters, as proposed by Ferrari and Orsi (1984), Nishida (1985), and Hirakawa (1988) (e.g. Carlton 1987; Hooff and Bollens 2004; Cordell et al. 2008). In Puget Sound, US, O. davisae was found to be one of the most common and abundant non-indigenous organisms found in ships from both foreign and domestic ballast discharges (Cordell et al. 2009; Lawrence and Cordell 2010). In contrast, O. brevicornis and O. aruensis are distributed widely in the subtropical-tropical coastal waters of the Indo-Pacific (Giesbrecht 1891; Früchtl 1923; Wellershaus 1969; Nishida 1985), while the geographic distribution of

O. wellershausi is still unknown except for the type locality (Pearl River estuary, China: Ferrari 1981). Records of the occurrence of O. brevicornis in the Mediterranean (e.g. Pesta 1920; Vaisierre and Seguin 1980; Shuvalov 1980) should be considered with caution, since these records are not accompanied with any descriptions of features that distinguish O. brevicornis from other related species (Nishida 1985). A revision of actual species should be carried out in the Mediterranean.

There is also evidence that shows O. aruensis is an estuarine species while O. brevicornis is more stenohaline and distributed in more saline waters than the former, although their distributions may partially overlap (Table 1; Nishida 1985; Chew and Chong 2011). The water temperature and salinity at the collection sites (16–17°С, 17–18 psu) and their yearly fluctuation in the surface waters of the Black Sea (6–25°С, 17–18 psu: e.g. Ovsyaniy et al. 2000; Repetin et al. 2003; Ivanov et al. 2006; Kondrat’yev 2010) are consistent with those in the temperate embaymental waters where O. davisae has been recorded (rather than in tropical-subtropical waters).

In the Black Sea the occurrence of O. brevicornis has been reported mostly from near-shore waters, such as Sevastopol Bay (Zagorodnyaya 2002; Gubanova and Altukhov 2007) and Novorossiysk and Tuapse Ports (Selifonova 2009). Selifonova et al. (2008) reported the occurrence of O. brevicornis from open waters of the western Black Sea, but did not indicate exact localities nor abundance. Temnykh et al. (in press) observed, for the first time, high abundances (> 9000 ind. m-3) of O. brevicornis in an offshore area in the Black Sea off the Crimean Peninsula (depth: ca. 1700 m). However, the specimens identified as O. brevicornis were re-examined and proved to be O. davisae. It is unknown whether the significant size difference in the specimens (collected during this research) between the two collection sites represents infraspecific variation due to different environmental conditions during development, or distinct populations with genetic differences; this invites a further study applying molecular genetics.

In summary, this research and previous records strongly suggest that O. brevicornis that has been reported to be recently introduced into the Black Sea is indeed O. davisae. The true absence of the species before 2001 should be confirmed on the basis of a retrospective analysis

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of samples covering areas of the Black Sea from bays to offshore waters.

If we assume the absence of O. davisae from the original Black Sea fauna, the following hypotheses may be proposed for the introduction of O. davisae from the coastal waters of East Asia: (1) direct introduction from East Asia in ships’ ballast waters (as in the cases of, e.g. the veined Rapa whelk Rapana venosa, the shrimp Palaemon macrodactylus and the blood cockle Anadara inaequivalvis: Skolka and Preda 2010) ; (2) secondary introduction of the Mediterranean populations, which were introduced and settled in some regions of the Mediterranean (such as those in Barcelona, Saiz et al. 2003), either by the copepods’ dispersal along coastal waters through the Turkish Straits System, which act as a strong barrier for many species (Oguz and Öztürk 2011) (e.g. the pelagic copepod Acartia tonsa: Kovalev et al. 1998; see also Oguz and Öztürk 2011 for examples from other animals), or in ships’ ballast waters (see Selifonova 2011 for copepod examples). However, the possibility cannot be ruled out that O. brevicornis and O. aruensis (or one of them) may have also been introduced into the Black Sea, if we consider the wide distribution of these species in the coastal waters of the Indo-Pacific region and the potential for their introduction in ships’ ballast waters from the countries where these species are distributed and where the ports of origin may be located.

For a better understanding of the current status of the Oithona species in the Black Sea and the history of their introduction, it is necessary to re-examine the samples previously collected from the Black Sea, directly examine the copepod species in ballast waters of ships arriving at ports in the Black Sea, and inquire into the historical records of the ships’ origins and destinations, on the basis of precise species identifications.

Acknowledgements

The authors would like to express their sincere gratitude to Dr. Yuri N. Tokarev, Dr. Victor V. Melnikov and Dr. Julia A. Zagorodnyaya for providing the information on temperature and salinity, and for their help in sampling and other field activities. Special thanks are due to Dr. Frank D. Ferrari and two anonymous reviewers for their invaluable advice on the manuscript and Dr. Monica Sullivan for editing the English text. Publication of this paper was supported by the EC 7th Framework Programme through the enviroGRIDS project (Grant Agreement No. 26740).

References

Atukhov DA, Gubanova AD (2006) Oithona brevicornis Giesbrecht in the Sevastopol Bay in October, 2005-March, 2006. Morskoy Ekologicheskiy Zhurnal (Marine Ecology Journal) 5: 32

Carlton JT (1987) Patterns of transoceanic marine biological invasions in the Pacific Ocean. Bulletin of Marine Science 41: 452-465

Chew LL, Chong VC (2011) Copepod community structure and abundance in a tropical mangrove estuary, with comparisons to coastal waters. Hydrobiologia 666: 127-143, http://dx.doi.org/10.1007/s10750-010-0092-3

Cordell JR, Bollens SM, Draheim R, Systema M (2008) Asian copepods on the move: recent invasions in the Columbia–Snake River system, USA. ICES Journal of Marine Science 65: 753-758, http://dx.doi.org/10.1093/icesjms/fsm195

Cordell JR, Lawrence DJ, Ferm NC, Tear LM, Smith SS, Herwig RP (2009) Factors influencing densities of non-indigenous species in the ballast water of ships arriving at ports in Puget Sound, Washington, United States. Aquatic Conservation: Marine and Freshwater Ecosystems 19: 322-343, http://dx.doi.org/10.1002/aqc.986

Ferrari FD (1981) Oithona wellershausi, new species, and O. spinulosa Lindberg, 1950 (Copepoda: Cyclopoida: Oithonidae) from the mouth of the Pearl River, China. Proceedings of the Biological Society of Washington 94: 1244-1257

Ferrari FD, Orsi J (1984) Oithona davisae, new species, and Limnoithona sinensis (Burckhardt, 1912) (Copepoda, Oithonidae) from the Sacramento San-Joaquin Estuary, California. Journal of Crustacean Biology 4: 106-126, http://dx.doi.org/10.2307/1547900

Früchtl F (1923) Cladocera and Copepoda der Aru-Inseln. Abhandlungen der Senckenbergischen Naturforschenden Gesellschaft 35: 449-457

Giesbrecht W (1891) Elenco dei Coepodi pelagici reccolti dal tenente di bascello Gaetano Chierchia durante il viaggio della R. Corvetta “Vettor Pisani” negli anni 1882-1885, e dal tenente dal vascello Francesco Orsini nel Mar Rosso, nel 1884. Atti dell’Accademia nazionale dei Lincei. Rendiconti, Ser. 4, 7: 474-481

Giesbrecht W (1893 ["1892"]) Systematik und faunistik der pelagishen Copepoden des Golfes von Neapel. Fauna und Flora des Golfes von Neapel und der angrenzenden Meeresabschnitte 19: 1-831, pls. 1-54

Gubanova A, Altukhov D (2007) Establishment of Oithona brevicornis Giesbrecht, 1892 (Copepoda: Cyclopoida) in the Black Sea. Aquatic Invasions 2: 407-410, http://dx.doi.org/ 10.3391/ai.2007.2.4.10

Hirakawa K (1988) New records of the North Pacific coastal planktonic copepods, Acartia omorii (Acartiidae) and Oithona davisae (Oithonidae) from southern Chile. Bulletin of Marine Science 42: 337-339

Hooff RC, Bollens SM (2004) Functional response and potential predatory impact of Tortanus dextrilobatus, a carnivorous copepod recently introduced to the San Francisco Estuary. Marine Ecology Progress Series 277: 167-179, http://dx.doi.org/10.3354/meps277167

Humes AG, Gooding RU (1964) A method for studying the external anatomy of copepods. Crustaceana 6: 238-240, http://dx.doi.org/10.1163/156854064X00650

Ivanov VA, Ovsyaniy EI, Repetin LN, Romanov AS, Ignatyeva OG (2006) Hydrological and hydrochemical regime of the Sebastopol Bay and its changing under influence of climatic and anthropogenic factors. Marine Hydrophysical Institute, National Academy of Sciences of Ukraine, Sevastopol, 90 pp

Oithona in Black Sea

431

Kasyan VV (2010) Holoplankton of ship ballast waters in the port of Vladivostok. Russian Journal of Marine Biology 36: 167-175, http://dx.doi.org/10.1134/S1063074010030028

Kondrat’yev SI (2010) Features of the dissolved oxygen distribution in the Sevastopol Bay in 2006–2007 Marine Hydrophysical Journal 2: 63-76

Kovalev AV, Besiktepe S, Zagorodnayaya J, Kideys A (1998) Mediterraneanization of the Black Sea zooplankton is continuing. In: Ivanov L, Oguz T (eds), Ecosystem medelings as a managemant tool for the Black Sea. NATO ASI Ser 1. Global Environment Change, pp 199-207

Lawrence DJ, Cordell JR (2010) Relative contributions of domestic and foreign sourced ballast water to propagule pressure in Puget Sound, Washington, USA. Biological Conservation 143:700-709, http://dx.doi.org/10.1016/j.biocon. 2009.12.008

Lee JH, Chae J, Kim W-R, Jung SW, Kim JM (2001) Seasonal variation of phytoplankton and zooplankton communities in the coastal waters of Tongyeong in Korea. Ocean and Polar Research 23: 245-253

Nishida S (1985) Taxonomy and distribution of the family Oithonidae (Copepoda, Cyclopoida) in the Pacific and Indian Oceans. Bulletin of the Ocean Research Institute, University of Tokyo No. 20: 1-167

Nishida S, Ferrari FD (1983) Redescription of Oithona brevicornis Giesbrecht and O. aruensis Früchtl, new rank, with notes on the status of O. spinulosa Lindberg. Bulletin of the Plankton Society of Japan 30: 71-80

Nishida S, Tanaka O, Omori M (1977) Cyclopoid copepods of the family Oithonidae in Suruga Bay and adjacent waters. Bulletin of Plankton Society of Japan 24: 120-157

Oguz T, Öztürk B (2011) Mechanisms impeding natural Mediterranization process of Black Sea fauna. Journal of Black Sea/Mediterranean Environment 17: 234-253

Ohtsuka S, Otani M, Soh HY, Kim M, Lee W, Huang C, Kimmerer WJ, Shimono T, Hanyuda T, Kawai H, Ueda H, Yamaguchi Y (2008) Relationships between presence or absence of non-indigenous copepods and ballast water at some international ports of Japan. Bulletin of the Plankton Society of Japan 55: 115-126

Orui-Sakaguchi S, Ueda H, Ohtsuka S, Soh HY, Yoon YH (2011) Zoogeography of planktonic brackish-water calanoid copepods in western Japan with comparison with neighboring Korean fauna. Plankton and Benthos Research 6: 18-25, http://dx.doi.org/10.3800/pbr.6.18

Ovsyaniy EI, Kemp RB, Repetin LN, Romanov AS (2000) The hydrologo – hydrochemical regime of Sevastopol Bay under anthropogenic impact as based on the studies conducted during 1998 – 1999. In: Ecological Safety of Coastal and Shelf Zones and Comprehensive Use of Shelf Resources. Collelcted Scientific Papers, National Academy of Science of Ukraine, Marine Hydrophysical Institute, Institute of Biology of the Southern Seas, Sevastopol, pp 79-103

Pesta O (1920) Die Plankton copepoden der Adria. Zool. Jb. Sust. 43: 471-660

Repetin LN, Belokopytov VN, Lipchenko MM (2003) Winds and waves in the coastal zone of the southwest part of Crimea. In: Ecological Safety of the Coastal and Shelf Zones and Complex Utilization of the Shelf Resources. Sevastopol, Ecosi-Gidrophizika, pp 13-28

Saiz E, Calbet A, Broglio E (2003) Effects of small-scale turbulence on copepods: The case of Oithona davisae. Limnology and Oceanography 48: 1304-1311, http://dx.doi.org/10.4319/lo.2003.48.3.1304

Skolka M, Preda C (2010) Alien invasive species at the Romanian Black Sea coast – Present and perspectives. Travaux du Museum National d’Historie Naturelle ”Grigore Antipa” 53: 443-467

Selifonova ZhP (2009) Oithona brevicornis Giesbrecht (Copepoda, Cyclopoida) in harborages of the northeastern part of the Black Sea shelf. Inland Water Biology 2: 30-32

Selifonova JP (2011) Ships' ballast as a primary factor for 'Mediterranization' of pelagic copepod fauna (Copepoda) in the Northeastern Black Sea. Acta Zoologica Bulgarica 63: 77-83

Selifonova ZhP, Shmeleva AA, Kideys AE (2008) Study of copepod species from the western Black Sea in the Cruise r/v 'Knorr' during May-June 2001. Acta Zoologica Bulgarica 60: 305-309

Shuvalov VS (1980) Cyclopoid Copepods of Oithonidae family of the World Ocean. Nauka, Leningrad, pp 1-197

Temnykh A, Tokarev Y, Melnikov V, Zagorodnyaya Y (in press) Daily dynamics and vertical distribution of pelagic Copepoda in offshore waters in front of the South-Western Crimea (Black Sea) in Autumn 2010. Morskoy Ekologicheskiy Zhurnal (Marine Ecology Journal)

Vaissiere R, Seguin G (1980) Etude preliminare de peuplements de Copepodes (juillet 1977) en relation avec l’hydrologie des mers Tyrrhenienne et Ionienne. Oceanologica Acta 3: 17-29

Vasilenko VI, Bityukov EP, Sokolov BG, Tokarev YuN (1997) Hydrobiophysical device ‘SALPA’ of Institute of Biology of the Southern Sea used for bioluminescent investigation of the upper layers of the ocean. In: Hastings JW, Kricka LJ, Stanley PE (eds), Bioluminescence and Chemiluminescence: Molecular Reporting with Photons. J. Wiley and Sons, New York, pp 549-552

Wellershaus S (1969) On the taxonomy of planktonic Copepoda in the Cochin Backwater (a South Indian estuary). Veröffentlichungen des Instituts für Meeresforschung in Bremerhaven 11: 245-286

Zagorodnyaya YA (2002) Oithona brevicornis in the Sevastopol Bay: Is it a single event of a new invader in the Black Sea fauna? Morskoy Ekologicheskiy Zhurnal (Marine Ecology Journal) 61: 43