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First International Meeting "The invasion of the Caspian Sea by the comb jelly mnemiopsis - problems, perspectives, need for action", Baku, Azerbaijan, 24-26 April, 2001

The First International Workshop to discuss the problems of the invasion of the Caspian Sea by the comb jelly Mnemiopsis was held in Baku, Azerbaijan, 24-26 April 2001.


BP – British Petroleum
CEP – Caspian Environment Programme
DIAS- Database on Introduction of Aquatic Species
ERT – Environment Research Technology Ltd. (UK)
FAO – Food and Agricultural Organization, UN
GEF – Global Environment Facility, UN
GESAMP- Joint Group of Experts on the Scientific Aspects of Marine Pollution, UN
ICES – International Council for the Exploration of the Seas, UN
IMO – International Maritime Organization, UN
NGO – non governmental organization
SOCAR – State Oil Company of Azerbaijan Republic

At the Second Biodiversity Meeting, organized by the Caspian Environment Programme (CEP) in July 2000 in Almaty, Kazakhstan, the invasion and influence of exotic species in the Caspian Sea was discussed.

Experts from the participating countries provided information on the latest discoveries of species invading the Caspian Sea. The participants stressed the importance of investigating further the problems caused by introduced species, particularly in light of the recent discovery of the ctenophore Mnemiopsis in the Caspian Sea. The national experts recommended the CEP establish a special Working Group of world-recognized experts in this field to thoroughly investigate this problem.

The CEP then organized the First International Workshop to review the problem of opportunistic settlers (with specific attention to Mnemiopsis) in the Caspian Sea and advise a possible course of action.

Terms of Reference for the Workshop:

  • To review the state-of-knowledge of Mnemiopsis,

  • To review the history of the Mnemiopsis invasion of the Azov, Black, Marmara and Mediterranean seas,

  • To assess the sources and causes of Mnemiopsis introduction in the Caspian Sea and their connection with other destabilizing factors and development in the Caspian Sea region,

  • To assess the occurrence, distribution, reproductive biology, and physiological features of Mnemiopsis in the Caspian Sea,

  • To assess the impact (present and future) of this ctenophore on pelagic and benthic communities and the consequences for fisheries (especially sturgeon),

  • To identify potential natural and introduced controls on Mnemiopsis in the Caspian Sea, including potential environmental impacts,

  • To outline an action plan for Mnemiopsis in the Caspian Sea, identifying next actions and studies, and the participants of and sponsors for these actions.

The workshop was attended by experts from Azerbaijan, Islamic Republic of Iran, Kazakhstan, Russian Federation, Turkmenistan, well-known scientists studying the problem of Mnemiopsis and introduced species from around the world, and representatives of the United Nations Food and Agricultural Organization and the International Maritime Organization and the State Oil Company of Azerbaijan Republic, Environment Research Technology Ltd., and British Petroleum. (Attachment 1, word).

I. Opening of the Workshop

Dr. B. Muradov, Regional Coordinator of the Caspian Environment Programme (CEP), opened the meeting. He welcomed the participants of the meeting to Azerbaijan and stressed the importance of the meeting in addressing one of the most important emerging environmental problems in the Caspian Sea – invasion by Mnemiopsis. Mr. Muradov briefly introduced the history of CEP, described important milestones, major components, objectives, activities, and implementation modalities.

Dr. V.Vladimirov, Scientific and Information Officer of the CEP, presented the draft agenda for the meeting and minor changes that were incorporated in it. After a short discussion, the agenda was adopted (Attachment 2).

II. From the East Coast of the Americas to the Caspian Sea

Dr. R. Harbison described in detail the biology of Mnemiopsis in its original habitat, which before the 1980s, was restricted to the eastern seaboard of the Americas, with a range extending from Cape Cod, USA (41° N, 70° W) in the north, to Peninsula Valdez, Argentina (43° S, 64° W) in the south. This ctenophore is most common in bays and estuaries, and does not occur very far from shore, since it seems to do best in environments with high levels of food. In the 1980s, it was probably transported to the Black Sea in ballast waters. Dr. Harbison emphasized that Mnemiopsis has many of the characteristics of an ideal invasive species. It is a simultaneous self-fertilizing hermaphrodite; it is a feeding generalist, consuming a wide spectrum of food; it tolerates a wide range of environments, with salinity ranging between 3.4 and 75 ppt and temperatures ranging between 1.3° C and 32° C; at optimal temperatures (above 20° C), it develops rapidly, reaching full sexual maturity in 12 days. it responds to elevated food concentrations with rapid growth and reproduction (Attachment 3).

Dr. T. Shiganova presented the results of investigations of Mnemiopsis in the Black Sea and its effect on the ecosystem. Dr. Shiganova briefly described the history of the Mnemiopsis invasion of the Black Sea; she presented the situation with Mnemiopsis after 1995 which was characterized by a peak in biomass that was observed in spring and summer, followed by a second decrease. In 1998, a third increase in offshore waters produced an average biomass of 876 g WW m-2 (35 g WW m-3) and an average abundance of 463 m-2 (18 m-3). Dr. Shiganova also discussed vertical distribution of Mnemiopsis and seasonal dynamics and factors controlling population size (Attachment 4).

In his presentation, Dr. S. Vostokov described the results of studies on seasonal population dynamics, age structure, basic physiological and ecological characteristics of the new invader, the ctenophore Beroe ovata and its potential prey Mnemiopsis leidyi, that were studied in the northeastern Black Sea from September-October 1999 to November 2000 by the Institute of Oceanology of the Russian Academy of Sciences. In this period, the total number, biomass, size, distribution and hunting behavior of Mnemiopsis leidyi, Beroe ovata and other gelatinous macroplankton were sampled by means of different plankton nets, and examined by diving techniques and underwater video (Attachment 5).

Dr. G. Finenko presented the results of recent studies undertaken by the Institute of Biology of Southern Sea of the Ukrainian Academy of Sciences. The goal of this study was to estimate the predatory impact of the alien ctenophores Mnemiopsis leidyi and Beroe ovata on the planktonic community of inshore waters in the Black Sea. This study also addressed the annual dynamics of abundance, biomass and population structure of Mnemiopsis leidyi in 1995–1996. Both Mnemiopsis leidyi and Beroe ovata in Sevastopol Bay and adjacent water regions were also studied in 1999–2001 (Attachment 6).

Dr. S. Volovik explained the major problems with Mnemiopsis in the Azov Sea. He pointed out the consequences of the Mnemiopsis invasion on the ecosystem of the Azov Sea, which include: changes in the zooplankton structure and biomass, dramatic changes in pelagic and benthic feeding fishes. Dr. Volovik also described the specifics of biology of Mnemiopsis in the Azov Sea (Attachment 7).

Dr. A. Kideys presented the results of multiyear studies by Turkish scientists of Mnemiopsis distribution in Turkish waters. The first occurrence of Mnemiopsis from the Sea of Marmara was observed in October 1992. The average biomass (4200 g/m2) calculated by these authors was very high. The values obtained later (in July 1993, April 1998 and October 2000) were very low (less than 20 g/m2 in 1993 and close to zero in 1998 and 2000). After its first occurrence with values of 1.3 g/m3, the average values in Mersin Bay and Iskenderun Bay (northeastern Mediterranean) were again close to zero in subsequent years. This was similar to the Marmara case. The Mediterranean data suggested that Mnemiopsis was not able to establish as an abundant species in this region. Dr. Kideys described in more detail the results of the investigations in the southern part of the Black Sea (Attachment 8).

Dr. N. Aladin, in his presentation, described the introduction of invertebrates in the Aral Sea. In total, during the period from 1954 until 1986, eleven species of aquatic invertebrates were introduced into the Aral Sea and nine of them naturalized (Attachment 9).

Dr. Leppakoski presented in great detail the history of invasive species in the Baltic Sea. During the last 150 years, about 100 alien species have been recorded in the Baltic Sea, most of them being introduced unintentionally by shipping in the ballast water tanks or by hull fouling, or spread from their primary sites of introduction in adjacent freshwater bodies. The brackish nature of the Baltic Sea does not protect its waters from introductions of alien species. The biota of the Baltic are exposed to other brackish-water biotas of the world, owing to the breakdown of large-scale geographical barriers by ship traffic leading to an exchange of species. In addition to its contact with the Atlantic Ocean through the Danish Straits, the Baltic and its drainage area are connected to the Ponto-Caspian brackish seas (Black, Azov and Caspian Seas) by rivers and canals, which have been opened since the 1770s (Attachment 10).

III. Present State of Mnemiopsis population in the Caspian Sea – Countries’ Overview

Dr. A. Kasimov presented the most recent findings of Mnemiopsis in the Azerbaijan waters of the Caspian Sea. In the spring of 2000, in the mid- and southern Caspian Sea, scientists from Azerbaijan discovered a new ctenaphore species – Mnemiopsis leidyi, which most likely was introduced in the Caspian Sea in 1998-1999 from the Azov-Black Sea basin with ballast water through Volga-Don canal. Mnemiopsis was registered in the western part of the mid-Caspian Sea in May 2000, near Nabran settlement, in the northern Absheron Gulf, the coastal waters of the islands Pirallahi (Artem) and Oil Stones, and in the western part of southern Caspian – from Shikhov to the Bandovan areas, on the offshore oil fields Chirag, Azeri, Nakhichevan, Oguz, on the gas field Shakh-Deniz, along the pipeline Chirag-Sngachal terminal, and in the waters of Sangachal terminal (Attachment 11).

Dr. F. Shakirova described the situation with Mnemiopsis in the Turkmenistan waters of the Caspian Sea. In September 1999, Mnemiopsis was first recorded in the southern part of the Caspian Sea near the Karabogazgol Gulf. In the summer of 2000, during hydro-biological investigations near Turkmenbashi, Mnemiopsis was sampled in low quantities; the average size was 3- cm. In October 2000, high concentrations of Mnemiopsis were recorded near the Turkmenistan coasts (Attachment 12).

Dr. H. Negarestan presented results of recent studies conducted in Iran. The presence of the comb jelly Mnemiopsis leidyi in the Caspian Sea was recorded for the first time by the Iranian Fisheries Research Organization in 1995, and warning letters were issued in this regard. Researchers from Tarbiat Modarres University also reported the occurrence of this species in large numbers in 1999. Today, after almost six years, this species has increased in number and a reduction in the catch of the fish kilka has been linked with the presence of this comb jelly. However, further investigation is needed to prove the impact of Mnemiopsis on kilka stocks in the south Caspian Sea. It is also reported that Mnemiopsis has been found in funnel nets in large numbers. Two pilot studies were conducted in the southern Caspian; the results showed that in the winter of 2000, the maximum biomass of this ctenophore in the south Caspian Sea was 125 g/m2 in the Khazarabad region; and none was observed in the surface waters of Amirabad (Attachment 13).

Dr. T. Shiganova presented results of the recent studies of the special features of the biology of Mnemiopsis in the Caspian Sea (Attachment 14).

Dr. Yu Kim summarized the situation with Mnemiopsis in the Kazakh waters of the Caspian Sea. There have been no special investigations of Mnemiopsis in Kazakhstan yet. The only available information was collected during fishery studies in the northeastern Caspian by the Atyrau branch of the Kazakhstan Fishery Institute. In the areas of exploration drilling, in eastern and western Kashagan, with depths not exceeding 4-5 m, jelly-fish was found along the whole water column. Mnemiopsis was first found in the summer of 2000. Around the same period, it was also found, though more sparsely, in the area of Kalamkas field at depths reaching 10 m. However, towards the mouth of the Ural, no single ctenophore was found until late autumn (Attachment 15).

Dr. H. Dumont presented the summary of discussion initiated from the Caspian countries’ presentations on Mnemiopsis in the Caspian Sea:

  • Mnemiopsis has been found in the Caspian Sea in abundance from 1995 (Iran) to 1998 (Azerbaijan), with the first certified observation in 1999 (Russia); in late 2000, Mnemiopsis was recorded with findings of specimens of different sizes.

  • No quantitative information or data on Mnemiopsis is available, except for that recorded by Iran (up to 470 g/m2), Azerbaijan (77 g/m2), and Russia (160 g/m2).

  • Very different methods have been used to study Mnemiopsis; there is a strong need to have a common methodology.

  • The information on the effects of Mnemiopsis on the Caspian Sea is very fragmented and further investigation is necessary. All experts agreed that these impacts exist, but locally only, and not too seriously yet.

  • The ecology of Mnemiopsis in the Caspian Sea is very close to that in the Black Sea, but it is not identical. Additional studies are needed.

  • The experts agreed the Caspian Sea is facing an emergency, but it is not catastrophic yet. All countries agreed on the urgent need to address this issue.

  • No coordination of research of Mnemiopsis exists yet in the Caspian region, but all countries are ready to work together.

Dr. V. Ivanov summarized the results of investigations carried out by the Russian Caspian Institute for Fisheries in the last two years. Russian scientists first recorded Mnemiopsis in the south and middle Caspian Sea in the fall of 1999. In the summer of 2000, Mnemiopsis was found everywhere in these regions. In September 2000, it was first discovered in the north Caspian Sea at depths of 5.5 to 6.6 meters; the size of the species were in the range of 2.2-4.8 cm. Unfortunately, there is no data on Mnemiopsis distribution in the other parts of the Caspian Sea. Dr. Ivanov presented preliminary studies on the impact of Mnemiopsis on the ecosystem of the Caspian Sea; he has found changes in the zooplankton number and biomass, especially a decrease of Copepoda. He also presented the prognosis of Mnemiopsis impacts on fisheries (Attachment 16).

Dr. H. Dumont presented his view on the possible consequences of the Mnemiopsis invasion for the biodiversity of the Caspian. Expected effects can be qualitative and quantitative. Qualitative effects will lead to the elimination of certain biota, either directly or indirectly. Mnemiopsis, an indiscriminate pelagic hunter, will primarily attack the zooplankton, and because it is capable of expanding as long as it can find food, it will likely drive the zooplankton to near-extinction. Some more vulnerable species may effectively become extinct. Unfortunately, the “naпve” Caspian endemics of the group of the Onychopoda are likely to be among them (Attachment 17).

IV. Control of Invasion, Elaboration of an Action Plan

Dr. R. Harbison presented the theoretical strategies for the control of invasions of marine and brackish-water organisms developed by the United Nations Joint Group of Experts on the Scientific Aspects of Marine Pollution (GESAMP) in 1995 (Attachment 18). These measures include mechanical, chemical, physiological and genetic controls, as well as ecological control by habitat modification, and biological control. After thorough consideration, the Caspian countries’ experts agreed that biocontrol is the only suitable one for the Caspian Sea. Following this discussion, Dr. Harbison presented a proposal to use butterfish, Peprilus triacanthus, as a biological control agent to control the Mnemiopsis population in the Caspian Sea. The butterfish, Peprilus triacanthus, has many characteristics that make it a good biological control agent. Its range overlaps with much of M. leidyi's range in North America. It is a member of the perciform suborder Stromateoidea, a group that appears to specialize on eating gelatinous zooplankton. Members of this group have unique pharyngeal pouches equipped with spiny teeth that are used for the trituration of gelatinous organisms (Buhler, 1930). Their teeth and jaws are adapted for biting off pieces of gelatinous animals as well, so all morphological evidence indicates that these fishes are highly specialized predators of gelatinous organisms (Attachment 19).

Mr. S. Raaymakers presented the overview of the GEF Global Ballast Water Management Programme (GloBallast) and stressed the importance of prevention of ballast water introductions in the Caspian Sea. He pointed out that theoretically it is possible to establish a quarantine barrier on the Volga/Don river system. Mr. Raamekers emphasized that it is important for the Caspian Sea to address a range of species, not just Mnemiopsis (Attachment 20).

Dr. S. Volovik introduced the possibility of using Beroe Ovata to control the Mnemiopsis in the Caspian (Attachment 21). The results of recent investigations of Beroe Ovata in the Black and Azov seas clearly indicated that the abundance and biomass of Mnemiopsis in the regions where Beroe Ovata is abundant have decreased dramatically. The laboratory studies demonstrated that Beroe Ovata is feeding only on Mnemiopsis and Pleurobrahia; Beroe Ovata can tolerate low salinity. Dr. Volovik also emphasized the importance of thorough laboratory studies of Beroe Ovata using Caspian Sea water. After detailed discussion, the participants of the meeting agreed that, at present, Beroe Ovata was considered the best choice to control Mnemiopsis.

Mr. F. Marttin presented to the participants the Code of Practice on the Introduction and Transfer of Marine Organisms elaborated by ICES in 1995 and supported by FAO. He stressed the importance to follow the decision making process for any possible introduction of species to control Mnemiopsis population in the Caspian Sea. The major steps are: looking for local alternative; proposal (purpose and objective, why alien needed, alternatives, source of the stock, etc),;independent review (evaluating the proposal, impacts and benefits); monitoring and reporting (Attachment 22). Mr. Marttin also presented the FAO database on introduction of Aquatic Species (DIAS), which lists 3,150 records on introduction of 654 aquatic species from over 140 families.

Monitoring and Research

Dr. R. Harbison presented a proposal for low-cost monitoring of Mnemiopsis in the Caspian Sea. A standardized method that is extremely simple and gives a broad geographical coverage is preferable to a more sophisticated method that covers only a small part of the Caspian Sea. Information on how Mnemiopsis population levels change over the entire basin on a synoptic basis would be extremely valuable, and would also create a unique data set. This low-cost monitoring can be done with the cooperation of all of the Caspian basin countries, using the human resources that they have available in the form of secondary school classes, fishermen, NGOs, oil companies, and other volunteers. For the method to work, it should be extremely simple so that data can be collected on as near a daily basis as possible (Attachment 23).

The participants decided to form drafting groups to prepare contributions to the final report of the meeting. Three drafting groups were formed:

  1. Possible Scenarios (Appendix 1)
  2. Monitoring needs (Appendix 2)
  3. Biological Control Measures (Appendix 3)

IV Conclusions and Recommendations

  1. The participants of the meeting were briefed on the distribution patterns and biology of Mnemiopsis in the Americas, Mediterranean, Marmara, Black, and Azov seas.

  2. The participants were also informed about the situation with invasive species in the Aral and Baltic seas.

  3. The Caspian Sea countries presented the information on the latest findings of Mnemiopsis in the Caspian Sea.

  4. The meeting discussed in detail possible consequences of a Mnemiopsis invasion for bioresources and biodiversity, with special reference to the rich endemic fauna of the Caspian Sea.

  5. The participants were informed of the possible measures to control the Mnemiopsis population, elaborated by the GESAMP 1995 working group.

  6. Butterfish, Peprilus triacanthus, and the ctenophore Beroe ovata, are possible biological agents to control the Mnemiopsis population.

  7. The participants were informed of the activities of the GEF project on Global Ballast Waters control, implemented by IMO. The participants of the meeting stressed the importance of close cooperation between the Global Ballast Waters project and CEP for mutual benefit.

  8. The participants were briefed on the Code of Practice on the introduction and transfer of marine organisms developed by ICES and supported by FAO.

  9. The participants were informed of the proposal of the low-cost monitoring of Mnemiopsis in the Caspian Sea.

  10. The participants agreed that the situation with Mnemiopsis in the Caspian Sea in 2000 was serious.

  11. The participants agreed that there is a strong need for more data on the distribution of Mnemiopsis in the Caspian Sea, especially its impact on the biology and ecosystem.

  12. The participants of the meeting agreed that at the present time the most favorable measures, of all those listed in GESAMP report, are biological control measures.

  13. Understanding that the decision on any possible introduction of an alien species should be made (with consensus) by all Caspian countries, a majority of the meeting participants agreed that any action involving an introduction of an alien species should be preceded by a rapid and independent review of the proposal for introduction by a group of experts on biological invasions, with adequate knowledge of Mnemiopsis, according to the guidelines on the precautionary approach on inland fisheries and species introduction of FAO.

  14. The participants agreed that there is a strong need to apply standardized methodology to monitor, assess and forecast spatial and temporal changes in the Mnemiopsis population in the Caspian Sea.

  15. The participants stressed the need to develop and implement a common methodology for ballast water management in accordance with IMO guidelines in order to prevent future introduction of invasive species into the Caspian Sea.

  16. The participants recommended using the ICES Code of Practice on the introduction and transfer of marine organisms as reference guidelines if any biological control measures are proposed.

  17. The participants stressed the importance, as a first step, to try to identify a native species capable of controlling the Mnemiopsis population. From non native species two options were discussed: Beroe and Peprilus. Both have advantages and problems; but it was concluded that, although Peprilus, if successfully introduced, might become a new resource, knowledge of its biology is currently too fragmentary to consider it an option. Beroe ovata was therefore considered the best choice. This choice was facilitated by the expectation that Beroe would sooner or later enter the Caspian Sea along the same channel as Mnemiopsis.

  18. The participants agreed on a scenario for reacting to a possible outburst of Mnemiopsis in 2001 and beyond (Appendix 1).

  19. The participants discussed proposals they developed for monitoring the Mnemiopsis population in the Caspian Sea (Appendix 2).

  20. The participants developed a follow-up strategy for further studies of Beroe ovata before any introduction is proposed (Appendix 3).

  21. The Caspian countries’ experts requested the CEP to create a Regional Working Group of experts on biological invasions.

V. Workshop’s Closure

The workshop’s participants noted the high productivity of the meeting, emphasizing the considerable input of organizers. The Chairman expressed his gratitude to workshop participants for active, well-oriented work, and to the organizers of the workshop, interpreters, and supporting staff. He pointed out the importance of the decisions made, and wished participants further successes.

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