Appendix 3 workshop 1

No doubts that a comprehensive study of the new invasive species, which is threatening the biological resources of the Caspian, is urgently needed.

The disastrous results of the Mnemiopsis invasion into the Sea of Azov give rise to concerns of potential destruction of trophic systems in the South, Middle and partly North Caspian ensuing its invasion into this sea. The claim is made by certain scientists (Volovik, 2000) that unless large scale and efficient actions were taken to control development of the population of Mnemiopsis, the unique natural system and important fisheries of the Caspian would be lost. Considering that commercial fisheries of the Caspian have incurred heavy losses after invasion of the comb jelly due to a sharp drop in sprat catches, there is an urgent need to develop a common, scientifically substantiated, action plan to save the ecosystems of the Caspian Sea from detrimental impact of the invasive comb jelly Mnemiopsis.

By accounts of researchers, the ctenophore was found in the Caspian in 1997-1998. All Caspian jellyfishes (endemics of the Caspian and those, which penetrated earlier) occur in small numbers and they don’t have a significant effect on the total biomass of food organisms of the Sea. A considerable growth of the biomass of Mnemiopsis was recorded in the South and the Middle Caspian in 2000, along with a drop in the biomass of mezoplankton (Shiganova et al. 2000; Sokolskiy, Shiganova, Zykov 2001).

The workshop, which was held in Baku (24-26 April 2001) to discuss the problem of the invasion into the Caspian of the comb jelly Mnemiopsis, boosted attention to this problem. The workshop noted that large-scale development of Mnemiopsis in the Caspian Sea could have a disastrous effect on the whole biota of the sea. First of all, a biological explosion of the new invader can radically change the species composition and biomass of mezoplankton, and be followed by a decrease in numbers of the most abundant commercial species – sprats and all other pelagic species. In view of a high percent of endemic species among the animals of the Caspian Sea, and the outcomes of the invasion of Mnemiopsis into the Black Sea, one can conclude that the biological diversity of the Caspian is under serious threat. Therefore, the working group, which was established to study this ctenophore in the framework of the Caspian Environment Programme (CEP), prepared a Methodology to study the invasion of Mnemiopsis and other jelly-like organisms into the Caspian Sea for environmental impact assessment of the ctenophore on the ecosystem of the Caspian Sea. In this regards, the initiative and actions undertaken by the CEP to study this organisms deserve special attention.

Taking into account that the invasion of the ctenophore indeed imperils fish stocks of the Caspian, the Azerbaijan Research Institute of Fisheries developed a research program in April 2001 to study distribution, abundance and biomass of the jellyfish in the Azerbaijan Sector of the Caspian Sea and submitted it for consideration of the CEP leadership. Having considered the work program provided by our Institute, experts of the CEP suggested to the leadership of their program supporting the Institute in conduct of the entire research program.

The research program includes conduct of surveys at the following five stationary transects in the Middle and South Caspian – Yalama, Siazan, Primorsk, Neftchala and Lenkoran (depths 0-25m), at existing permanent observation stations of the Institute. Besides, it was also planned to take samples at additional transects, marked on the map (see map).

The following stations were chosen and approved:

• Yalama coast (settlement Yalama 6);
• Siazan (set. Zarat);
• Sangachaly (set. Primorsk);
• Neftchala (Kura estuary); and
• Lenkeran (port Liman).

It was decided to conduct initial studies at several stations at transects that comprise the whole coastal zone at depths of 3, 5 and 10m, and also at the depth of 25m, where safety measures allow.

All equipment and methodology were agreed with CEP experts, which held several joint researches with the personnel of the institute (A. Kideys).

Abiotic factors of the environment were also measured: temperature, salinity, transparency and oxygen content in water at all transects and depths (Table 1).

Studies and sampling started in July and have been continuing up to the present. Mnemiopsis of different size and age groups was found at all transects. The highest biomasses of Mnemiopsis were recorded at the stations in the vicinity of Sumgayit (Jorat) - at the depth of 10m (up to 271,0 gm/m³), at the settlement Shikhovo – at the depths of 3m (up to 247,8 gm/m³), at the settlement Liman (137,0 gm/m³) and in Siazan – at the depths of 5m (151,9 gm/m³). More than 7 thousand specimens of ctenophore were processed during this period.

An analysis of Mnemiopsis distribution by size groups in the summer (July-August) of 2001 showed that smaller size groups with the length up to 15mm prevailed all along the coastline (Table 2) averaging to 89.1% (from 70.7 to 98.8%).

It should be noted that the size composition strongly varied. The biggest specimens of jellyfish of the size group 61-65mm were found singly. However, small specimens (young and juvenile stages) constituted more than 70% at the majority of transects. Complete predomination of small specimens (91,3%) was observed in Lenkeran at the depth of 10m.

In autumn the studies were extended and comprised 10 transects. An analysis of size characteristics showed that the number of ctenophores of smaller age groups even more increased and size ranges narrowed. The major part of the population consisted of specimens with the length up to 10mm, they fluctuated from 71.1 to 100% and making 86.3% in average. The minimal concentrations of the ctenophore were recorded at northern transects (Yalama and Khachmaz), and a trend of southward increase of abundance was noted (Table 3).

The high content of young specimens testifies of relentless reproduction during 4 months (July-October).

The November samplings conducted at seven transects showed a considerable reduction in abundance of Mnemiopsis, amounting to less than 5% of the previous values. Mnemiopsis was not found at certain transects (Borisov’s bank, Kura estuary) at all or was found but singly. However, at the same time, more than 60% of the whole material was collected only at the transect Liman (Table 4).

All data pertaining to spread, abundance and size-weight composition of the ctenophore in the coastal zone of the Azerbaijan sector of the Caspian Sea were filled into a special database, created for this purpose.

Analyses of samples of zooplankton revealed scarcity of species composition of plankters. Copepods were represented only by one species - Acartia clausi, which dominated among other plankton organisms. Other plankton organisms included larvae of nereis, mollusks and balanus (Table 5).

Feeding habits of the ctenophore and its qualitative and quantitative parameters by size groups were also studied in accordance with the work program (Table 6).

As it shown in the table below, the species composition of ctenophore’s diet corresponds to that of zooplankton.

Feeding of sprats taken in summertime at the Borisov’s bank was characterized by the following parameters (Table 7): 54,5% had empty alimentary tracts, 33,4% of alimentary tracts were filled with singly specimens of Cypris balanus and only 9,1% had medium filling of alimentary tracts. The coefficient of fatness of sprats (by Clark) was low. All analyzed specimens of sprats were at the fifth stage of maturity of genital products, which was reflected in their coefficient of fatness by Fulton.

The research provided the following preliminary results:

• Mnemiopsis is ubiquitous all over the coastal zone in the Azerbaijan sector of the Caspian Sea;
• The highest biomass and abundance of the ctenophore was recorded in July-September;
• Juvenile comb jellies prevailed in all samples (length range up to 15mm in summer – 88,1%; up to 10mm in autumn – 86,3%); the maximal size of adult specimens was 61-65mm; and
• The range of food consumed by comb jellies entirely matched to the species composition of zooplankton as well as the range of food of plankton-eating fish, the biomass of plankton has a direct relationship with the abundance of comb jellies, whose biomass by far exceeds that of plankton.

• We believe it would be useful to conduct regular seasonal monitoring, which will allow for determining the major stages of development of Mnemiopsis (outset and end of active period, terms and periodicity of reproduction, etc.);
• Conduct cameral studies of comb jellies’ relation with abiotic environmental factors (temperature, salinity, oxygen) and range of feeding;
• Conduct of comprehensive studies of relationship of Mnemiopsis, Beroe and plankton organisms for the purpose of potential introduction of Beroe in the Caspian to reduce abundance of Mnemiopsis.

The proposed studies will allow for obtaining more detailed and conclusive information on the biology and distribution of Mnemiopsis, and will serves as the basis for development of a program for abatement of adverse consequences of its introduction on the biota of the Caspian Sea.

Table 1. Abiotic factors of the environment

Table 5. Qualitative indicators of zooplankton in shallow waters of the Middles and South Caspian in July 2001 (specimens/mg/m³)

Table 2. Characteristics of size groups of Mnemiopsis by transects of the Middle and South Caspian (%)
Summer 2001 (July-August)

Table 3. Characteristics of size groups of Mnemiopsis by transects of the Middle and South Caspian (%)
Autumn 2001 (September-October)

Table 6. Food composition of Mnemiopsis in shallow waters at western coast of the Caspian Sea
Summer 2001

Table 4. Characteristics of size groups of Mnemiopsis by transects of the Middle and South Caspian (%)
November 2001

Table 7. Feeding of plankton-eating fish (sprat) at western coast of the Caspian Sea
Summer 2001

54,5 % - empty, 36,4 % - singular, 9,0 % - medium