A. S. Mikaelyan

A. S. Mikaelyan
P.P. Shirshov Institute of Oceanology · Department of Biology

Ph.D.

About

56
Publications
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Introduction
A. S. Mikaelyan currently works at the Department of Biology, P.P. Shirshov Institute of Oceanology. A. does research in Marine Biology. Their current project is 'Long-term phytoplankton dynamics'.

Publications

Publications (56)
Preprint
Full-text available
Impact of climate change on phytoplankton dynamics
Article
Full-text available
Studies of the annual dynamics of phytoplankton in the NE Black Sea at two stations on the shelf and the continental slope were conducted in 2016, 2017, and 2019. The species composition of phytoplankton has not undergone significant changes compared to previous decades. The coccolithophore Emiliania huxleyi, small flagellates, and diatoms determin...
Article
Aim Mesoplankton of the Southern Ocean is the key trophic link between phytoplankton and other consumers and an important part of the biological carbon pump, a critical component of climate regulation. Although general patterns of mesoplankton distribution and life cycles are known, we still cannot estimate mesoplankton standing stocks at specified...
Article
Full-text available
The seasonal evolution of the species composition and depth of the deep maximum of phytoplankton (DPM) in the Black Sea has been studied. Vertical series of phytoplankton samples were collected at 278 stations in the deep-water basin during a 35-year period from 1985 to 2019. On average, the bulk of the total phytoplankton biomass is in the upper m...
Article
The Black Sea is characterized by powerful summer coccolithophore blooms with strong interannual variability. In this paper, we used satellite and Bio-Argo measurements to show that the emergence of extremely strong blooms in several years was caused by intense vertical entrainment of nutrients from deep isopycnal layers during winter convection. I...
Article
The spatial and temporal variability of winter coccolithophore blooms in the Black Sea is studied using satellite measurements for 2003-2017 and Bio-Argo buoys data. Analysis shows that such blooms can occupy the entire upper 60-meter layer with satellite-derived estimates of surface cell concentration reaching in some years 3.0·106 cells l-1. On a...
Article
Full-text available
Рассмотрены разные типы мезомасштабной вихревой динамики с точки зрения их влияния на количество и таксономическую структуру планктона, в основном фитопланктона. Вихревые структуры всех видов, включая циклонические, антициклонические, линзовидные антициклонические и фронтальные вихри, а также дипольные структуры активно воздействуют на планктон. Ра...
Article
Full-text available
The year‐to‐year seasonal variability of the vertical distribution of concentration of chlorophyll‐a (Chla) in the Black Sea, its relation to light (PAR) and mixing conditions were studied based on the six‐year (2014‐2019) measurements of Bio‐Argo floats. Variations in PAR caused by changes in incoming solar radiation and light attenuation determin...
Article
Full-text available
Different types of mesoscale eddy dynamics are considered in the paper from the viewpoint of their effect on the plankton (mainly phytoplankton) amount and its taxonomic structure. The eddy structures of all types, including cyclonic, anticyclonic, water-body anticyclonic and frontal ones, as well as the dipole structures, actively affect plankton....
Article
In autumn 2017, the influence of strong storms and mesoscale physical processes on phytoplankton has been studied in the Black Sea. Data on the taxonomic composition and biomass of phytoplankton, the concentration of chlorophyll-a (Chl), particulate organic carbon, primary production, chemical and physical properties of the environment were obtaine...
Chapter
Full-text available
State of the Environment of the Black Sea (2009-2014/5) available: http://www.blacksea-commission.org/SoE2009-2014/SoE2009-2014.pdf
Article
Bio-Argo measurements of the backscattering coefficient (bbp) were used to investigate the time-depth evolution of coccolithophore blooms in the Black Sea. Five years of Bio-Argo data obtained in 2014-2018 revealed two distinct peaks of bbp corresponding to the winter and early summer coccolithophore blooms. The latter started in the upper mixed la...
Article
Effect of invasive ctenophores Mnemiopsis leidyi and Beroe ovata on low trophic webs of the Black Sea ecosystem T.A. Shiganovaa,⁎, A.S. Mikaelyana, S. Monchevab, K. Stefanovab, V.K. Chasovnikova, S.A. Mosharova, I.N. Mosharovaa, N. Slabakovab, R. Mavrodievab, E. Stefanovab, D.N. Zaskoa, B. Dzhurovab a Shirshov Institute of Oceanology, Russian Acade...
Technical Report
Full-text available
Editors: J. Slobodnik, B. Alexandrov, V. Komorin, A. Mikaelyan, A. Guchmanidze, M. Arabidze, A. Korshenko
Technical Report
Full-text available
This document has been prepared in the frame of the EU/UNDP Project: Improving Environmental Monitoring in Black Sea - Phase II(EMBLAS-II), ENPI/2013/313-169 Editors: J. Slobodnik, B. Alexandrov, V. Komorin, A. Mikaelyan, A. Guchmanidze, M. Abaridze, A. Korshenko, S. Moncheva
Article
The dynamics of the autumn development of phytoplankton in the Black Sea were investigated using satellite-derived chlorophyll-a concentration (Chl), which was estimated for two regions in the deep sea over a 20-year period. We analysed 8-day composite Chl images along with changes in: (i) nutrient concentration obtained from in-situ measurements,...
Article
Full-text available
This volume contains the main results of the EC FP7 “The Ocean of Tomorrow” Project CoCoNet, divided in two sections: 1) a set of guidelines to design networks of Marine Protected Areas in the Mediterranean and the Black Seas; 2) a smart wind chart that will allow evaluating the possibility of installing Offshore Wind Farms in both seas. The concep...
Article
The phenology of the winter–spring phytoplankton bloom in the Black Sea was investigated on the basis of the satellite-derived chlorophyll concentration (Chl) for the recent 18-year period. Data for the 8-day Chl were analysed, together with changes in the nutrient concentration, sea surface temperature (SST), photosynthetically available radiation...
Article
Full-text available
In many regions phosphorus limits coccolithophore growth, whereas nitrogen generally controls development of diatoms. We tested the hypothesis that a change in nutrient composition defines the alternation of these algae. Data on phytoplankton, nutrients, chlorophyll and primary production were obtained in May-June from 2002 to 2012. Coccolithophore...
Article
Full-text available
During the period from 1970s to 2000s in the open waters of the Black Sea ecosystem has passed the stage of eutrophication, which manifested in high values of chlorophyll a, biomass of phytoplankton, primary production, etc. The goal of current research is to trace the long-term (1969–2008) dynamics in supply of nutrients and their ratios in the py...
Data
Full-text available
In 2002–2005 Emiliania huxleyi blooms occurred annually and reached up 1.5 × 106 cells/liter in May-June. The total phytoplankton biomass for the layer 0–50 m during E. huxleyi bloom on the Gelendzhik shelf corresponded to the mesotrophic waters (0.2–0.4 g/m3). The population contributed to the biomass up to 60%. In 2004–2005 E. huxleyi bloom was a...
Article
Full-text available
In spring and early summer 2005, a new Mediterranean diatom species, Chaetoceros trondsenii, was noted in phytoplankton of the northeastern Black Sea. The parameters of the created phytoplankton species dynamics model were determined in experiments with nitrogen and phosphorus supply. Computational experiments with the model gave the following resu...
Article
Full-text available
A five-year study of the interannual changes observed in May–June during the mass reproduction of coccolithophorids was carried out in the northeastern part of the Black Sea. The long-term dynamics were analyzed using the data on the phytoplankton collected during the last 40 years. The fraction of coccolithophorids represents either 20 or 60% of t...
Article
Full-text available
In spring and early summer 2005, a new Mediterranean diatom species, Chaetoceros trondsenii, was marked in phytoplankton of the northeastern Black Sea. The parameters of the created phytoplankton species dynamics model were determined in experiments with nitrogen and phosphorus supply. Computational experiments with the model gave the following res...
Article
Full-text available
In May-June 2005 in the northeastern Black Sea, on its shelf, slope, and in the open sea, intensive (up to 1.92kh{cyrillic}10 5 cells/L) growth of alien species, Chaetoceros throndsenii, in the Black Sea was observed. At the same time, a mass development of coccolithophore Emiliania huxleyi (Lohmann) Hay et Mohler took place, cell numbers of which...
Article
Full-text available
A role of phosphorus in regulation of mass development of Emiliania huxleyi (Lohm.) Hay et Mohl. in the northeastern part of the Black Sea was investigated in laboratory experiments with use of bath culture and mathematic methods. It was shown that low nitrogen/phosphorus ratio does not necessarily point to nitrogen as limiting factor for coccolith...
Chapter
Full-text available
BSC, 2008. State of the Environment of the Black Sea (2001 - 2006/7). Edited by Temel Oguz. Publications of the Commission on the Protection of the Black Sea Against Pollution (BSC) 2008-3, Istanbul, Turkey, 448 pp.
Article
Full-text available
It is shown that, in 2002–2005, the mass development of the coccolithofore Emiliania huxleyi on the Gelendzhik shelf occurred annually and in May–June its abundance reached 1.5 × 106 cells/l. In 2004–2005, the bloom of E. huxleyi was accompanied by a mass development of the diatom alga Chaetoceros subtilis var. abnormis f. simplex (0.6–0.9 × 106 ce...
Article
A large amount of data is needed to study the variations occurring in ecosystems during long time periods over a vast basin. This evident statement appears to be hardly realized in practice, especially in biological studies based on sample processing to the level of species performed by a specialist. Despite the extremely labor consuming processing...
Data
It is shown that in 2002-2005 mass development of coccolithofore Emiliania huxleyi on the Gelendzhik shelf (northeast Black Sea) occurred annually and in May-June its abundance reached 1500000 cells/l. In 2004-2005 bloom of E. huxleyi was accompanied by mass development of diatom alga Chaetoceros subtilis var. abnormis f. simplex (600000-900000 cel...
Article
Full-text available
On the basis of the observations performed in June-July 2004, the main parameters of the coccolithophorid blooming are described. Emiliania huxleyi was the dominant species. Its maximum abundance amounted to 1.5-6.0 × 106 cells 1-1. High concentrations occurred throughout the entire area studied (up to 70 miles from the shore). The main share of th...
Chapter
Full-text available
The invasion of the Black, Mediterranean and Caspian Seas by the American Ctenophore, Mnemiopsis leidyi Agassiz: a multidisciplinary perspective and a comparison with other aquatic invasions CONTENTS PREFACE PART 1. Mnemiopsis leidyi 1. Mnemiopsis leidyi: distribution and effect on the Black Sea ecosystem during the first years of invasion in c...
Article
Full-text available
The patterns of vertical distribution of the populations of dinoflagellates with heterotrophic and mixotrophic types of nutrition were studied in the open waters of the Black Sea during September-October 1992. The population of Ceratium fusus dominated the dinoflagellates; it consisted of cells with both autotrophic and heterotrophic types of nutri...
Article
The abundance of phytoplankton and its size groups is analyzed in three regions of the Pacific Ocean: Subarctic, Northern Subtropical, and Eastern Equatorial. Both our own and published data were used. Picoplankton dominates all three regions. The role of nanoplankton is especially high in biomass; however, sometimes the contribution of microplankt...
Chapter
The pelagic ecosystem of the open part of the Black Sea was analyzed from the point of view of its temporal changes on interannual and seasonal basis. The material was collected during interdisciplinary expeditions to the Black Sea, between 1978–1996. The observed interannual variability is discussed for all plankton groups except protozooplankton....
Chapter
The pelagic ecosystem of the open part of the Black Sea is analyzed from the point of view of its sustainability. The peculiarities of plankton community in the temperate region result in regular seasonal oscillations of high range, the biomass values varying 5–10 times during the year. In the coastal regions of the Black Sea the values of primary...
Article
The species composition, cell number and biomass of pico-, nanno-, and microalgae were estimated for the open waters of the northern subtropical zone of the Pacific Ocean and the coastal waters off North America. The total phytoplankton abundance was also evaluated. The productivity of these waters was newly estimated. The distribution of phytoplan...
Article
Full-text available
Species composition and spatial distribution of heterotrophic algae were studied in the Black Sea in autumn, 1992. Total phytoplankton biomass varied during that period from 8 to 30 g m-2. The autotrophic species Ceratium fusus and Rhizosolenia calcar-avis dominated. The list of species of heterotrophic dinoflagellates consisted of 14 species. The...
Article
Data on total biomass and taxonomic structure of phytoplankton communities, collected in the Black Sea during the period 1978–1992 were analysed. Comparisons were restricted to the biological summer-autumn season, when the ecosystem is in most stable state. Changes in phytoplankton communities were investigated in the entire basin as well as in fiv...
Book
Recent decades have seen a degradation of the environmental quality in semi-enclosed seas, which are particularly sensitive to population pressures due to their naturally low flushing rates related to their geometry. The North Sea, Baltic Sea and the Black Sea are amongst the most seriously threatened seas in the Euro-Asian region. Each semi-enclos...
Article
The intensity of chlorophyll thermochemiluminescence (TCL) associated with lipid peroxidation was examined in phytoplankton inhabiting the Black Sea and the Atlantic Ocean. In Black Sea nanophytoplankton, TCL intensity normalized to chlorophyll concentration was generally higher at depths with low chlorophyll contents. A similar TCL pattern was obs...
Article
Full-text available
Spatial distribution, cell division and cellular chlorophyll content were studied in populations of the diatom Nitzschia delicatula Hasle during the winter phytoplankton bloom in open waters of the Black Sea in 1991. This diatom contributed 39 to 87 % (mean 72 %) to phytoplankton biomass. Cell numbers were as high as 6 x 10(9) cells m(-3) and bioma...
Article
Material was collected from the Weddell Sea and the Bransfield Strait in January/April 1989. Data on size-taxonomic composition and biomass of phytoplankton communities and Ch1 concentration were obtained to estimate the chlorophyll a (Ch1) cell content. Single cell fluorescence measured microscopically was used as a relative index of cellular Ch1...
Article
Data are presented concerning the size, taxonomic and quantitative structure of the phytoplankton communities of surface waters in four climatic zones of the Southern Hemisphere world ocean. The results have been obtained using the up-to-date counting techniques. The structure of phytocenoses in the tropical and subtropical zones proved to be pract...

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Projects

Projects (2)
Project
We try to understand what mechanisms of regulation of the phytoplankton structure are the main. For this purpose, we use the field data obtained in the Black Sea, the Barents Sea and the Caspian Sea. We carry out experiments with natural populations of phytoplankton in different environmental conditions. We check some hypotheses using mathematical models.