Phytoplankton distribution and variation along a freshwater-marine transition zone (Kızılırmak River) in the Black Sea

AbstractBoth phytoplankton of the Kizilirmak River/Black Sea transition zone and their interactions with nutrients were investigated between July 2007 and December 2008. A total of 447 taxa belonging to the divisions: Cyanobacteria (24), Bacillariophyta (209), Bigyra (1), Cercozoa (1), Charophyta (11), Chlorophyta (32), Cryptophyta (11), Miozoa (119), Euglenozoa (14), Haptophyta (13), Ochrophyta (10) and Protozoa Incertae Sedis (2) were identified at 5 different sites in the study area. Seventy four taxa were recognized as new records for the Algal Flora of Turkey and 41 taxa were determined as HAB (Harmful Algal Bloom) organisms.According to the hierarchical clustering and MDS analyses, surface phytoplankton were distributed along the salinity gradient from freshwater to saline waters, and the early spring samples were separated from the other samples. However, in addition to the agglomerative hierarchical cluster analysis, the samples were divided into four groups – “Fresh”, “Brackish”, “Marine” and “Early spring-Marine” – as a result of MDS analysis.The results of this study revealed that the surface phytoplankton were influenced by the salinity and the Secchi Disc depth together with the seasonal water temperature dynamics and NO

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Engineering geophysical studies in the Black Sea from onboard the R/V Ashamba during 2017

Океанология ◽

10.31857/s0030-1574592319-320 ◽

2019 ◽

Vol 59 (2) ◽

pp. 319-320

Author(s):

N. N. Dmitrevskiy ◽

R. A. Ananyev

Keyword(s):

Transition Zone ◽

Continental Slope ◽

Black Sea ◽

Water Area ◽

The Black Sea ◽

Echo Sounder

In May and October 2017, expeditionary research was carried out in the area of Gelendzhik in the Black Sea at the R/V «Ashamba». The main tasks were the mapping of the seabed and the search for small-sized objects at the bottom of the water area using a WASSP WMB-3250 multibeam echo sounder. Surveys included areal surveying and drawing up bathymetric maps of test sites in Gelendzhik Bay and in the transition zone from the shelf to the continental slope. In addition, the echo sounder was used to search and determine the exact coordinates of the bottom seismograph installed at the seabed near the Divnomorskoye village in May 2016. The article presents the results of the work carried out.

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Variability of the food potential of the Kerch strait and the black sea pre-strait zone as a prospective area for the development of mollusks Mariculture

E3S Web of Conferences ◽

10.1051/e3sconf/202125804007 ◽

2021 ◽

Vol 258 ◽

pp. 04007

Author(s):

Nataliy Sitnik

Keyword(s):

Black Sea ◽

Suspended Matter ◽

Zooplankton Community ◽

The Black Sea ◽

Dynamic Factor ◽

Total Biomass ◽

Algal Flora ◽

High Productivity ◽

Larval Stages ◽

Kerch Strait

Based on the data of integrated observations, the variability of phytoplankton, the amount of suspended organic matter and zooplankton of the pelagic zone of the Kerch Strait and the pre-strait zone of the Black Sea is considered. The algal flora of the entire Black Sea, the Kerch Strait and the pre-strait is characterized by the predominance of diatoms over pyridineas (pyrrophytes or dinoflagellates). The study of the species range, number and biomass of the phytoplankton community during several periods of the year showed that its dynamics is largely dependent on seasonal weather changes (climate). In the process of phytoplankton development, several phases of autogenic succession were revealed. It is expressed in a sequential change in phytoplankton forms, changes in its abundance and biomass typical of the eastern shelf of the Black Sea. The zooplankton community of the Kerch Strait is represented by micro-, meso- and macro- zooplankton typical of the Black Sea. Microzooplankton is represented by zooflagellates and protozoa, as well as by early larval stages of planktonic crustaceans, apendicularia and mollusks. Its total biomass averages about 80 mg/m3.The above analysis of the collected material allows us to conclude that the distribution of suspended matter and larvae is related primarily to the peculiarities of water circulation in the strait. In the case of low concentrations of larvae, the dynamic factor can be decisive in the process of sedimentation intensity. The amounts of suspended matter can reach 20 mg/m3, which is 2-3 times higher than on average for the Black Sea. It further demonstrates the high productivity of waters and the prospects of the latter to be the area for commercial growing of mussels.

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A conservation palaeobiological approach to assess faunal response of threatened biota under natural and anthropogenic environmental change

Biogeosciences ◽

10.5194/bg-16-2423-2019 ◽

2019 ◽

Vol 16 (12) ◽

pp. 2423-2442 ◽

Cited By ~ 3

Author(s):

Sabrina van de Velde ◽

Elisabeth L. Jorissen ◽

Thomas A. Neubauer ◽

Silviu Radan ◽

Ana Bianca Pavel ◽

...

Keyword(s):

Black Sea ◽

Environmental Changes ◽

Sea Water ◽

Salinity Gradient ◽

Conservation Strategies ◽

The Black Sea ◽

Freshwater Species ◽

Lake System ◽

The Past ◽

Mollusc Species

Abstract. Palaeoecological records are required to test ecological hypotheses necessary for conservation strategies as short-term observations can insufficiently capture natural variability and identify drivers of biotic change. Here, we demonstrate the importance of an integrated conservation palaeobiology approach when making validated decisions for conservation and mitigating action. Our model system is the Razim–Sinoie lake complex (RSL) in the Danube Delta (Black Sea coast, Romania), a dynamic coastal lake system hosting unique Pontocaspian mollusc species that are now severely under threat. The Pontocaspians refer to an endemic species group that evolved in the Black Sea and Caspian Sea basins under reduced salinity settings over the past few million years. The natural, pre-industrial RSL contained a salinity gradient from fresh to mesohaline (18 ppm) until human intervention reduced the inflow of mesohaline Black Sea water into the lake system. We reconstruct the evolution of the RSL over the past 2000 years from integrated sedimentary facies and faunal analyses based on 11 age-dated sediment cores and investigate the response of mollusc species and communities to those past environmental changes. Three species associations (“marine”, “Pontocaspian” and “freshwater”) exist and their spatio-temporal shifts through the system are documented. Variable salinity gradients developed, with marine settings (and faunas) dominating in the southern part of the system and freshwater conditions (and faunas) in the northern and western parts. Pontocaspian species have mostly occurred in the centre of the RSL within the marine–freshwater salinity gradient. Today, freshwater species dominate the entire system, and only a single Pontocaspian species (Monodacna colorata) is found alive. We show that the human-induced reduced marine influence in the system has been a major driver of the decline of the endemic Pontocaspian biota. It urges improved conservation action by re-establishing a salinity gradient in the lake system to preserve these unique species.

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On Bulgarian sawflies, including a new species of Empria (Hymenoptera, Symphyta)

Deutsche Entomologische Zeitschrift ◽

10.3897/dez.66.34309 ◽

2019 ◽

Vol 66 (1) ◽

pp. 85-105 ◽

Cited By ~ 2

Author(s):

Andrew Liston ◽

Marko Prous ◽

Jan Macek

Keyword(s):

New Species ◽

Host Plant ◽

Coastal Zone ◽

Black Sea ◽

Early Spring ◽

The Black Sea ◽

Plant Associations ◽

North Eastern ◽

First Time ◽

A New Species

Thirty-nine species of sawfly (Symphyta) are recorded for the first time in Bulgaria. Most of these were collected during early spring of 2018, in the south-east of the country (Burgas and Varna Provinces). Empriaaridicola Macek & Prous, sp. nov. is described as new to science from specimens collected in several central, east and south European countries. Lectotypes are designated for Poecilosomaparvula Konow, 1892, Empriapravei Dovnar-Zapolskij, 1925 and E.pseudoklugi Dovnar-Zapolskij, 1929. Empriapravei and Sciapteryxbyzantina Benson, 1968 are at present only known in Europe from the coastal zone of the Black Sea. The new Bulgarian records of Hoplocampacantoti Chevin, 1986 and Neomessasteusloffi (Konow, 1892) represent large extensions in their recorded ranges, previously comprising respectively only northern France, and north-eastern Germany. Possible host plant associations are noted for several species, based on observations of adults.

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A conservation palaeobiological approach to assess faunal response of threatened biota under natural and anthropogenic environmental change

10.5194/bg-2019-6 ◽

2019 ◽

Author(s):

Sabrina van de Velde ◽

Elisabeth L. Jorissen ◽

Thomas A. Neubauer ◽

Silviu Radan ◽

Ana Bianca Pavel ◽

...

Keyword(s):

Black Sea ◽

Environmental Changes ◽

Sea Water ◽

Salinity Gradient ◽

Conservation Strategies ◽

The Black Sea ◽

Freshwater Species ◽

Lake System ◽

The Past ◽

Mollusc Species

Abstract. Palaeoecological records are required to test ecological hypotheses necessary for conservation strategies as short-term observations can be insufficiently to capture natural variability and identify drivers of biotic change. Here, we demonstrate the importance of an integrated conservation palaeobiology approach to make validated decisions for conservation and mitigating action. Our model system is the Razim-Sinoie Lake complex (RSL) in the Danube Delta (Black Sea coast, Romania), a dynamic coastal lake system hosting unique Pontocaspian mollusc species that are now severely under threat. The Pontocaspians refer to an endemic species group that evolved in the Black Sea and Caspian Sea basins under reduced salinity settings over the past few million years. The natural, pre-industrial RSL contained a salinity gradient from fresh to mesohaline (18 ppm), until human interventions reduced the inflow of mesohaline Black Sea water into the lake system. We reconstruct the evolution of the RSL over the past 2000 years from integrated sedimentary facies and faunal analyses based on 11 age-dated sediment cores and investigate the response of mollusc species and communities to those past environmental changes. Three species associations (marine, Pontocaspian, freshwater) exist and their spatiotemporal shifts through the system are documented. Variable salinity gradients developed, with marine settings (and faunas) dominating in the southern part of the system and freshwater conditions (and faunas) in the northern and western parts. Pontocaspian species have mostly occurred in the centre of the RSL within the marine–freshwater salinity gradient. Today, freshwater species dominate the entire system, and only a single Pontocaspian species (Monodacna colorata) is found alive. We show that the human-induced reduced marine influence in the system has been a major driver of the decline of the endemic Pontocaspian biota. It urges for improved conservation actions by re-establishing a salinity gradient in the lake system to preserve these unique species.

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Estimation of seasonal and inter-annual variations of phytoplankton in the Black Sea on the base of remote sensed data procession and chlorophyll a in situ measurements

Доклады Академии наук ◽

10.31857/s0869-5652485199-103 ◽

2019 ◽

Vol 485 (1) ◽

pp. 99-103

Author(s):

S. V. Vostokov ◽

L. I. Lobkovskiy ◽

A. S. Vostokova ◽

D. M. Solov'ev

Keyword(s):

Black Sea ◽

Early Spring ◽

In Situ Measurements ◽

The Black Sea ◽

Annual Variations ◽

Winter Convection ◽

Color Scanner ◽

Preceding Winter

The patterns of the seasonal and inter annual variability in the development of phytoplankton, including coc- colithophores, were studied in the northeastern part of the Black Sea in various seasons. The research was carried out on the base of remote sensed data provided by the Modis Aqua ocean color scanner and long-term ship observations. The results indicate that, in the coastal and open waters of the Black Sea, the development of phytoplankton reaches the highest level in the fall-winter and winter-spring seasons, i.e., in the periods of active winter convection. It was noted that there is a relationship between the level of coccolithophore development in the summer period and the minimal temperature of the sea surface layer in the preceding winter. The most active coccolithophore blooms, were observed after the coldest winters. Unusual winter and early spring coccolithophore blooms taking place in mild hydro meteorological conditions were registered in the Black Sea, on the base of satellite data and were confirmed by in situ measurements.

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Properties of main phytoplankton species of the Black Sea, determining the change in their dominance in annual dynamics

Issues of modern algology (Вопросы современной альгологии) ◽

10.33624/2311-0147-2020-1(22)-82-93 ◽

2020 ◽

pp. 82-93

Author(s):

Sergey G. Chekhutskiy ◽

Anna V. Lifanchuk

Keyword(s):

Black Sea ◽

Phosphorus Uptake ◽

Large Cell ◽

Early Spring ◽

Early Summer ◽

The Black Sea ◽

Phytoplankton Species ◽

Nitrogen And Phosphorus ◽

Seasonal Thermocline ◽

Specific Growth Rates

Using mathematical model, we tested three hypotheses of bloom regulation mechanisms for dominant phytoplankton species in the northeastern Black Sea. The model is based on the concept of intracellular regulation using the Droop equation, and values of the model constants that satisfy the conditions of domination are found. The bloom of the small-cell diatom Pseudo-nitzschia pseudodelicatissima is due to higher specific growth rates than other species in early spring. The half-saturation constants and minimum quotas for mineral nutrition elements (nitrogen and phosphorus) are also relatively high. In late spring and early summer, the bloom of coccolithophore Emiliania huxleyi is usually recorded. Prerequisites are a low half-saturation constant for nitrogen uptake and minimum quota for this nutrient. The third mechanism gains strength in the summer with the deepening of seasonal thermocline and the dominance of large-cell diatoms. It was shown that for the supremacy of large diatom Proboscia alata, it is necessary to have low half-saturation constants for the phosphorus uptake and minimum quotas for this nutrient.

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