scholarly journals CURRENT VIEWS ON THE DIVERSITY AND DISTRIBUTION OF DEEP-WATER MEIOBENTHOS AT THE TURKISH SHELF (BLACK SEA)

2017 ◽  
Vol 14 ◽  
pp. 60-73
Author(s):  
Nelli G. Sergeeva ◽  
Derya Ürkmez

Deep-water meiobenthos of Turkish shelf has been evaluated at the Black Sea exit of İstanbul Strait (Bosphorus) and off Sinop peninsula as a result of three scientific cruises. Taxonomic diversity of meiobenthos communities was studied at the Black Sea exit of Bosphorus on a transect with a depth range of 75-300 m. The bottom sediments were collected at the area during two cruises, on board RV "Arar'' (of Turkey) and ''Maria S. Merian" (of Germany) in November 2009 and April 2010, respectively. Data on meiobenthos inhabiting both normoxic and extreme conditions was collected in the studied area and meiobenthos composition included 26 high level taxa. In addition, 2-3 morphotypes of benthic fauna were recorded as incertae sedis, which require further study. The number of higher taxa decreased from 22 to 14-8 when switching from oxygenic conditions (50-125 m) to the anoxic hydrogen sulphide environment (226-300 m). The constant components of meiobenthos included protists (Ciliophora, Gromiidea and soft-shelled Foraminifera), and metazoans were constantly represented by Nematoda and Harpacticoida. In 2011, a quantitative study on meiobenthic composition of the oxic/anoxic interface at the western part off Sinop Peninsula (Southern Black Sea) has also been investigated. The material was collected by ROVs during the expedition (Black Sea Leg) of the exploration vessel (E/V) Nautilus. Results showed that the taxa composition of meiobenthos ranged from 4 to 10 major groups. Free-living marine nematodes were numerically the dominant taxon at each station. Total abundances decreased in parallel to increasing water depth, hence decreasing oxygen levels.

2019 ◽  
Vol 59 (1) ◽  
pp. 166-169
Author(s):  
P. A. Stunzhas ◽  
M. B. Gulin ◽  
A. G. Zatsepin ◽  
E. A. Ivanova

In the northeastern Black Sea the search was performed for living eukaryotic organisms (micro- and meiobenthos) in hypoxic and anoxic conditions as well as measurement of O2 in the bottom water layer and in the upper layer of sediments. The results have shown the presence of a deep maximum abundance of zoobenthos in a depth range of 215–244 m. This aggregation of benthic fauna occupies a layer of 30 m along the vertical. In general, the proportion of active meiobenthos was no greater than 1.5% of the total number of organisms recorded from the sample.The presence of aerobic benthos near the upper boundary of the H2S zone can be explained by: sliding down of sediments from a higher depth; quasi-periodic O2 supply due to fluctuations in the position of the isopycna and/or sinking of waters downslope in the bottom Ekman layer. Also, in the case of physical entry of oxygen into the bottom layer, it can remain for a relatively long time in the upper part of the H2S zone due to the lack of deep Mn+2 flux and reaction with it.


2021 ◽  
Vol 39 ◽  
pp. 30-45
Author(s):  
Nelly G. Sergeeva ◽  
Yuriy S. Tarariev ◽  
Roman V. Gorbunov ◽  
Nikolay K. Revkov ◽  
Natalya A. Boltachova ◽  
...  

The results of the first studies of the ecosystem state of the underwater part of the channel, artificially created in the middle of the 20th century on the western shore of the Balaklava Bay (Sevastopol) as a naval base of the Black Sea Fleet for the submarines repair, are presented. Channel's ecosystem is determined by uniqueness of anthropogenic formation and considered as analogue of natural Black Sea cave. Hydrospelological survey of the channel and biological studies allowed assessing its current state, the nature of biofouling of its walls and anthropogenic and technical pollution of the bottom. Macrofauna of the channel wall biofouling is represented by the Mytilaster lineatus community, which has a high level of species abundance (about 80 species have been registered) and quantitative development. Both in taxonomic diversity and in quantitative terms, this community is comparable to the rocky substrate community near open Crimean coasts, but with a smaller share of crustacean group development. Due to weakened hydrodynamics, well developed fauna of bryozoans forming plurannual crusty structures and single sponges is observed on the channel's walls. In contrast to the channel walls biofouling, its bottom macrofauna has relatively lower quantitative and qualitative composition. Meiobenthos in the channel’s wall biofouling is represented by 18 higher taxa (type, class, order) of Protozoa and Metazoa with predominance of harpacticoids by abundance. Meiobenthos of the soft bottom of underground channel is represented by 15 higher taxa with predominance of free-living nematodes and harpacticoids by abundance. Average density of meiobenthos in the channel’s bottom sediments is comparable with similar parameters of its development in open water areas and Sevastopol bays.


2019 ◽  
Vol 4 (2) ◽  
pp. 11-22 ◽  
Author(s):  
I. P. Bondarev ◽  
L. V. Bondarenko

This article containing information about study of the taxocene Arthropoda is a continuation of the cycle describing the composition of the consortium of the invasive gastropod mollusk Rapana venosa (Valenciennes, 1846). The consortium of R. venosa is still an unaccounted component in the biocenosis structure of the Black Sea shelf. The material used and the research methods are discussed in detail in previous articles of the cycle. The purpose of this work is to describe the complex of epibiontic organisms and to compile an annotated list of Arthropoda taxa of the consortium of R. venosa. The 27 species of phylum Arthropoda found in the consortium belong to two subphyla: Chelicerata (class Arachnida) and Crustacea (classes Malacostraca and Hexanauplia). The only representative of the arachnids class (Arachnida; Acari) – Rhombognathus notops (Gosse, 1855) – was found just twice (in a single specimen in samplings of 2016 and 2017). The shell of R. venosa serves as a substrate for the development of a variety of algae – favorable habitat for the epiphyton, which causes a high number and diversity of crustaceans in this biotope. The greatest taxonomic diversity was noted for the Malacostraca class – 25 species belonging to 22 genera of 19 families. Arthropods are represented in consortium of R. venosa by two main ecological groups – sedentary and mobile epibionts. The largest species diversity of Arthropoda is inherent in free-living mobile forms (23 species). Sedentary forms, which inferior in number of species (4), dominate by quantity (86 %) and biomass (94 %). The only representative of Cirripedia – Amphibalanus improvisus (Darwin, 1854) – is the most common (53 % of the total quantity) and massive crustacean, which contributes the most significant amount to the biomass (91.8 %) of Arthropoda in the consortium. More than 50 % of the Arthropoda species in the consortium are polyphages; phytophages are 20 %; detritophages are 28 % of the total number of arthropod species. The only adult specimen of fish ectoparasites is the isopod Elaphognathia bacescoi (Kussakin, 1969) found in a consortium of sandy rapa-whelk at a depth of 8 m in the Golubaya Bay of Sevastopol. All of the 27 species of Arthropoda found are present in the consortium of the sandy R. venosa, and only 3 species are noted on the rocky rapa-whelks. The differences in the composition of the consortium of the two ecomorphs of R. venosa are mainly due to the great development of the epiphytes and the reduced dynamics of the water masses in the sandy rapa-whelk habitats in Sevastopol region. Due to their taxonomic diversity, quantity and biomass, Arthropoda are an important element of the bottom biocenosis spatially and trophically associated with individuals of the largest gastropod of the Black Sea – R. venosa.


Author(s):  
Svetlana Rubtsova ◽  
Svetlana Rubtsova ◽  
Natalya Lyamina ◽  
Natalya Lyamina ◽  
Aleksey Lyamin ◽  
...  

The concept of a new approach to environmental assessment is offered in the system of integrated management of the resource and environmental safety of the coastal area of the Black Sea. The studies of the season and daily changeability in the bioluminescence field in the Sevastopol coastal waters has been conducted. For the first time considerable differences in the bioluminescence field seasonal changes in the surface and deep water layers and the reasons conditioning this phenomenon have been shown, using a method of multidimensional statistical analysis. The bioluminescence field vertical profile change in the Black sea coastal waters in the autumn period at night has been studied. It has been shown that according to the character of bioluminescence parameters dynamics a water column can be divided into layers: upper (0 – 35 m) and deep water (36 – 60 m). It has been revealed that life rhythms of the plankton community are the main reason for the bioluminescence field intensity variability. It has been revealed that 14-hour periodicity of the bioluminescence field is related to the changes in light and its variations with 2,5…4,5 hours are conditioned by planktonts endogenous daily rhythms. And here biotic factors effect mostly periodicity of the bioluminescence field intensity increase and fall down at the dark time of the day. Abiotic factors are of less importance in circadian rhythmic of the bioluminescence field in the neritic zone.


1992 ◽  
Vol 99 (1-3) ◽  
pp. 1-27 ◽  
Author(s):  
Timothy W. Lyons ◽  
Robert A. Berner
Keyword(s):  

Author(s):  
Nikolay V Esin ◽  
Alexey V. Khortov ◽  
Nikolay I. Esin

One of the important unsolved problems related to the evolution of living conditions on Earth is the mechanism of the rapid transformation of the Black Sea from a shallow lake-type sea into a deep-water basin, the earth's crust in the central part of which does not have a granite layer. There is no explanation as to how “granite-free depressions” were formed at the bottom of the sea, which are currently covered by sediment. Investigations of these processes were started in the middle of the last century by scientists-geologists of the Institute of Oceanology of the Russian Academy of Sciences and its South. In this article, the authors propose a mechanism for the destruction of the earth's crust and the formation of depressions in the inner seas during the Messinian crisis.


Author(s):  
I. N. Timukhin ◽  
B. S. Tuniyev

For the first time the level of relics of the high-mountain flora of the northwestern edge of the highlands of the Caucasus has been established. The Fisht-Oshten Massif and the Black Sea Chain have a uniquely high level of relics - 51.0% (617 species), with a predominance of Tertiary-relic species - Rt - 41.2% (498 species). The second largest representation is a group of Holocene relics - Rx - 7.3% (88 species), the minimum represented Pleistocene relics - Rg - 2.5% (31 species). The relic level of alpine species is one of the highest in the Caucasus and is 52.8% (338 species). Alpine species also have predominance of Pliocene relics - 46.7% (299 species), the number of glacial relics is 2.5% (16 species), the share of xerothermic relics - 3.6% (23 species). In the preservation of relic species revealed general trends, depending on the remoteness of local flora from the main diaspora on the Fisht-Oshten Massif and the modern area of the meadow belt. These trends persist in Tertiary relics, while other patterns are observed for glacial and Holocene relics. The number of glacial relics fades to the west, most clearly it can be seen in alpine species. The number of Holocene relics as much as possible on the edge areas (Fisht-Oshten Massif and Mt. Semashkho) and minimally on the central peaks of the Black Sea Chain, where the Holocene expansion of xerophyte plants was insignificant.


2017 ◽  
Vol 2 (2) ◽  
pp. 20-33 ◽  
Author(s):  
I. P. Bondarev ◽  
N. K. Revkov

Gastropod mollusk-invader Rapana venosa (Valenciennes, 1846) in the 1940s took a free ecological niche terminal predator in benthic communities of the Black Sea shelf and has become an important element of the ecosystem. The ability of rapa whelk to have a devastating impact on the biocenosis filter feeders determines the necessity of constant monitoring of this species populations’ state. The study of rapa whelk showed that the ecological role of this species is not limited to predation. Fairly large shell R. venosa is a solid substrate for alga, attached and restrictedly movable (sedentary) benthic animal organisms, among which mobile free-living forms sometimes find shelter. The aim of the work is to describe specific complex of epibiotic organisms formed on rapa-whelk shells, which is regarded as a consortium, where of R. venosa is the core. To study the consort community of R. venosa a sampling was made in 7 regions of the northern part of the Black Sea: 1 – Mamaia beach, Romania, 2 – the north-western part of the Black Sea (NWBS), Crimean sector, 3 – Sevastopol, 4 – Alupka, 5 – Yalta – Alushta, 6 – Karadag, 7 – the Kerch Strait. The sampling in the coastal zone (less then 15 m depth) was carried out by SCUBA and snorkel diving, deeper (up to 40 m) was used “Ocean-50”grab corer was used. Totally of 856 specimens of R. venosa were collected and analyzed. The main bulk of the material in the amount of 750 specimens of R. venosa was sampled in the coastal zone in Sevastopol vicinity (south-western Crimea) at the depth range of 1.5–10.0 m. The collection of the rapa whelk specimens was carried out totally and each specimen was placed in a separate plastic bag indicating the collection area, depth and biotope. Along with the mollusks sampling, visual observations and photographic fixation of hydrobionts in situ were carried out. Based on the research results the taxonomic list of rapa whelk epibiotic organisms was extended and for the first time the taxonomic composition of the mobile forms permanently or temporarily present in the R. venosa consortium was given. The first part of the investigation provides a list of rapa whelk epibionts taxa relating to four (Porifera, Cnidaria, Bryozoa, Chordata) of the seven detected Phyla with indication of sampling depths and bottom type and comments on the frequency of occurrence, the quantity and of their interaction with the consortium core. Phylum Porifera is represented by 1, Bryozoa – 3 Cnidaria – 2 and Chordata – 4 species. The drilling sponge Pione vastifica was found in all the investigated areas, except region 2 (NWBS), with a frequency of 20 to 90 % and the shell surface area damage was up to 100 % (average 30–35 %). Not numerous representatives of Cnidaria were found singly in the region 3 (Actinia equina) and in the region 5 (Diadumene lineata). Bryozoans are the most common group of animal-consorts of rapa whelk present in all the areas of our research. The frequency of their occurrence ranged from 10 to 100 %, the covering area of the shell surface was from 0 to 85 %. More than 90 % of the total surface area of rapana shell cover with bryozoans and their occurrence is in Cryptosula pallasiana. The second bryozoans’ species on development indices is Conopeum seurati, which was found in areas 3, 6 and 7, where the occurrence was up to 30 % and the coverage was up to 25 %. The other 3 species of bryozoans (Schizomavella auriculata, Bowerbankia imbricata, Hippothoa sp.) were found rarely. Representatives of Chordata – 2 species of ascidians (Botryllus schlosseri, Ciona intestinalis) and 3 species of fish (Diplecogaster bimaculata, Parablennius tentacularis, Scorpaena porcus) were recorded singly in regions 2, 3, 5. For the four Phyla of animal organisms considered the consorts list of R. venosa of the sandy bottom biotopes (10 species) is twice more numerous than that of the rocky eco-form (5 species). The organisms studied are of a different degree and nature of relations with the core consortium from commensalism to parasitism. Generalized information on periphyton and total coverage of rapa whelk shells with epibiotic complex is given. The results of the work show that in the Black Sea R. venosa has become an important element of the ecosystem, increasing biological diversity of the bottom fauna due to the formation of its own consortium complexes of epibiontic organisms.


Author(s):  
Paulo S. Young ◽  
Helmut Zibrowius ◽  
Ghazi Bitar

The geographic distribution of Verruca stroemia and V. spengleri are reviewed. Verruca stroemia ranges from the White, Barents, Norwegian, and North Seas south to Portugal to the Algarve and to Gorringe Bank. All of the records of this species from the Mediterranean Sea are considered to be V. spengleri. Verruca spengleri occurs in the Azores and Madeira archipelagos, in southern Spain (Cádiz), throughout the Mediterranean Sea from Gibraltar to Lebanon, and in the Black Sea. But a distinct deep-water Verruca species seems to occur in the deep Mediterranean.


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