Peculiarities of the Biology of Mnemiopsis leidyi (A. Agassiz) under Conditions of the Black Sea

The proximate biochemical composition and metabolic rates of ctenophores Mnemiopsis leidyi and Beroe ovata from the Black Sea were examined with respect to starvation conditions. Although organic matter content in B. ovata was two times higher than that of M. leidyi (2.51 ±0.53 and 1.14 ±0.17 mg g-1 of wet weight, respectively), these species did not significantly differ in their biochemical composition. In both species protein formed about 80% of the total organic matter, lipids amounted to about 10%. Carbohydrate and amino acids measured separately made up less than 6.5% of the total organic matter. Under experimental starvation (18 days at 16—18°C for B. ovata and 8 days at 12.4°C for M. leidyi), wet weights of both ctenophore species were reduced by 9.4% and 9.3% d-1, respectively. The rate of organic matter decrease was nearly two times lower than that of wet weight being on average 5.9% d-1 in M. leidyi and 5.5% d-1 in B. ovata. There was no trend in percentage of the four major biochemical categories with starvation time. The glycogen content in polysaccharides reached maximum values in freshly collected ctenophores (76.0 ±7.9% in B. ovata, and 86.6% in M. leidyi), but it was reduced substantially (34.4 ±2.7% in B. ovata and 18.3—28.8% in M. leidyi) with starvation. Monosaccharide content, expressed as a percentage of total carbohydrate, decreased from 39.9% to 13.5% in B. ovata, and from 45.8% to 14.3—23.2% in M. leidyi. The relationship between respiration rate (R) and wet weight (W) of individuals during the starvation can be expressed by power function R = R1 Wk (r2=0.85—0.94; P>0.001) for both ctenophore species. On average, k values were 0.95 and 0.83 in B. ovata and in M. leidyi, respectively. By the end of the starvation, metabolic rate per unit wet weight decreased by 33% in B. ovata and 46% in M. leidyi. Organic matter utilization was almost totally explained by respiration of ctenophores in the experiments and exceeded metabolic requirements of studied species by 11% and 15%, correspondingly. As compared with Mnemiopsis, Beroe has better tolerance to starvation which explains to some extent the success of the species survival during prolonged periods of food shortage in the Black Sea conditions.

Download Full-text

Bioresource capacity of the black sea and its development by the national fishery in the XX and XXI centuries

Вестник Российской академии наук ◽

10.31857/s0869-587389111105-1119 ◽

2019 ◽

Vol 89 (11) ◽

pp. 1105-1119

Author(s):

Dmitry Ya. Fashchuk

Keyword(s):

Black Sea ◽

Marine Pollution ◽

Chemical Pollution ◽

The Black Sea ◽

Mnemiopsis Leidyi ◽

Commercial Fish ◽

Dynamics Of Population ◽

History Of ◽

Natural Dynamics ◽

Catch Composition

In this paper, the history of the formation, dynamics of structure, and species composition of the main objects of the national fishery in the Black Sea from the moment of the fall of the Crimean Khanate in 1783 up to today are analyzed, as well as the structure of commercial biological resources of the sea formed throughout the geological history of development of the Ponto-Caspian Basin (more than 30 million years). The geography and catch composition, scales, and methods of fish harvesting in the twentieth and twenty-first centuries are examined. The stages of intensification and reduction of fish harvesting success and the causes of these fluctuations (natural dynamics of population abundance, press of predatory species, hydrotechnical construction, marine pollution, overfishing, poaching) are identified. The author shows that at the end of the twentieth century, the Russian fishing industry entered a depressed state, while the other Black Sea countries increased their average annual total catch. At the same time, starting at the beginning of the twenty-first century, due to the lessening of press of warty comb jelly (Mnemiopsis leidyi), a decrease in the level of oil and chemical pollution of coastal and shelf waters in the northern Black Sea, and a reduction in industrial production on the seacoast and watershed territories, the ecological situation in the Russian territorial waters improved significantly and many formerly commercial fish populations started to recover.

Download Full-text

Gelatinous macroplankton of the open pelagial and shelf of the Black Sea: Distribution in autumn 2016 and interannual changes in biomass and abundance

Marine Biological Journal ◽

10.21072/mbj.2019.04.3.01 ◽

2019 ◽

Vol 4 (3) ◽

pp. 3-14 ◽

Cited By ~ 1

Author(s):

B. E. Anninsky ◽

S. M. Ignatyev ◽

G. A. Finenko ◽

N. A. Datsyk

Keyword(s):

Black Sea ◽

Oxygen Sensor ◽

Abiotic Factors ◽

Lower Boundary ◽

Somatic Growth ◽

Sea Surface ◽

The Black Sea ◽

Mnemiopsis Leidyi ◽

Trophic Relations ◽

Order Of Magnitude

The gelatinous macroplankton community of the Black Sea renews annually and functionates differently depending on the complicated system of trophic relations and interannual fluctuations of biotic and abiotic factors. Its monitoring is necessary for the evaluation of the current state and possible vectors of evolution of the whole pelagic ecosystem. For this purpose the data on the composition and distribution of gelatinous organisms were collected on the 89th cruise of the RV “Professor Vodyanitsky” (September – October of 2016) at 62 stations located in coastal areas and in the open sea to the south and southwest of Crimea. Samples were taken with the Bogorov – Rass net (inlet area of 0.5 m², mesh of 300 µm) using vertical net hauls from the bottom to the sea surface in the shallow shelf and from the lower boundary of the oxygen zone [according to the dissolved oxygen sensor CTD SBE plus (Sea Bird)] to the sea surface – in deepwater areas. Aurelia aurita and 3 ctenophore species (Mnemiopsis leidyi, Pleurobrachia pileus, and Beroe ovata) were present together in the 90 % of the samples (on 56 stations). In spite of some increase in average biomass of every species in deep sea areas, and, particularly, of A. aurita up to 260 g per m², there was no difference between the data of 2016 and 2010 (p > 0.05). The abundance of A. aurita increased by about one order of magnitude (p < 0.001); the abundance of P. pileus increased 2–5 times (p < 0.001); of B. ovata – 3–15 times (p < 0.01). M. leidyi abundance increased only at the outer Black Sea shelf; in other regions it could have been restricted by B. ovata predation. A. aurita linear specific growth rate in 2016 was one of the lowest for the last 15 years. Slow somatic growth of the jellyfish indicates unfavorable conditions for this species in 2016. However, the jellyfish biomass was higher than that of previous years because of the huge abundance of the spring generation. The weakening competition with planktivorous ctenophores may lead to even greater increase in the ecological valence of A. aurita among other gelatinous predators in the nearest future.

Download Full-text

ZOOPLANKTON OF THE NORTH-EASTERN PART OF THE BLACK SEA OFF THE COAST OF TAMAN IN THE SUMMER-AUTUMN PERIOD 2018–2019

Journal of Oceanological Research ◽

10.29006/1564-2291.jor-2021.49(1).2 ◽

2021 ◽

Vol 49 (1) ◽

pp. 26-36

Author(s):

N.P. Remizova

Keyword(s):

Black Sea ◽

Taxonomic Composition ◽

The Black Sea ◽

Mnemiopsis Leidyi ◽

Autumn Period ◽

The North ◽

Oithona Davisae ◽

Invading Species ◽

North Eastern ◽

North Eastern Part

The taxonomic composition and quantitative characteristics of zooplankton in the northeastern part of the Black Sea near the Taman coast in the summer-autumn period of 2018–2019 were studied. Zooplankton was represented mainly by eurythermic and thermophilic forms. All the discovered species and taxa are currently typical of the Black Sea, including the invading species: copepods Acartia tonsa, Oithona davisae, and combtails Mnemiopsis leidyi, Beroe ovata. The average number of zooplankton in 2018 ranged from 2.7–15.9 thousand copies/m3, the biomass – 0.02–0.14 g/m3; its indicators in 2019; they were lower, respectively, 2.0–5.6 thousand copies/m3 and 0.02–0.07 g/m3. These indicators were within the values recorded earlier, in 2013–2014. A significant part of the coastal zooplankton is meroplankton, which accounted for 5–69% of the population and 4–47% its biomass. O. davisae dominated amoung copepods. This speciest was leading in numbers in both years except June 2019. Despite the similarity of the taxonomic composition of zooplankton, the dominant species in terms of biomass differed by month in two years.

Download Full-text