Horizontal and Vertical Distribution of Phytoplankton in the Alpine Lake Sevan (Armenia) during the Summer Cyanoprokaryota Bloom

Сахарова, Е. Г.; Крылов, А. В.; Sabitova, R. Z.; Tsvetkov, A. I.; Gambaryan, L. R.; Մամյան, Ա. Ս.; Gabrielyan, Bardukh; Hayrapetyan, Armine; Khachikyan, Termine

doi:10.1134/s1995425520010072

Cited by 15 publications

(9 citation statements)

References 11 publications

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“…Already in 1964, abundant blooms of blue-green algae (cyanobacteria) were observed here, which recurred periodically until the second half of the 1970s and during the decade 2006-2016 [15]. But their particularly intense flowering in the summerautumn period has been observed from 2018 to the present, which indicates eutrophication of the lake [8,9,[16][17][18][19].…”

Section: Introductionmentioning

confidence: 63%

Water Dynamics and Morphometric Parameters of Lake Sevan (Armenia) in the Summer–Autumn Period According to Satellite Data

Ginzburg,

Kostianoy,

Sheremet

et al. 2024

Remote Sensing

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Here, we explore the dynamics of the waters of eutrophicated Lake Sevan in the modern period, using MSI Sentinel-2 satellite images of different months in different years (2017–2022) and SAR Sentinel-1 images of similar dates. The main objective of the study is to investigate the spatiotemporal variability of the horizontal circulation of this lake and to establish whether the scheme of cyclonic water circulation in the deep-water part of Large Sevan, given in a number of publications, which does not imply water exchange between its littoral and deep-water zones, corresponds to the real picture of currents in the surface layer of the lake in the summer–autumn period (period of pronounced water stratification and intense phytoplankton bloom). The analysis performed convincingly showed that there is no constant cyclonic gyre on the scale of the deep-water part of Large Sevan (≈20 km) during the period under consideration. In most cases, non-stationary eddy dynamics are observed in Large Sevan, including mesoscale and submesoscale eddies, eddy dipoles (mushroom-shaped flows), and their packings. Often the entire deep-water part of Large Sevan is occupied by a two-cell (dipole) or even three-cell (cyclonic eddy with two anticyclones of similar size) water circulation. The time scale of the observed variability is several days. Such variable water circulation in different months (i.e., with different density stratification of water) of different years in a basin with a fairly homogeneous bottom and a slight indentation of the shoreline raises the assumption that the main reason for the non-stationary dynamics in Large Sevan is the variability of the wind effect on its surface layer. The cyclonic gyre in Small Sevan (8–9 km) is a permanent element of the circulation and maintains its position north of the strait between Small and Large Sevan. This gyre and attached anticyclonic eddies in the southern part of its periphery, as well as cyclonic submesoscale eddies in the northern part of Large Sevan, close to the strait, affect the water exchange between Small and Large Sevan in both directions. An additional objective of the study is a validation of the morphometric parameters of Lake Sevan (level, surface area, and water volume), contained in the near-real time HYDROWEB database, LEGOS, France (June 1995–January 2024), based on their comparison with the corresponding values of these parameters from gauging stations in Armenia. It is shown that, with a qualitative correspondence of the nature of lake level changes according to altimetric and instrumental measurements, its values in the HYDROWEB database exceed the data of gauging stations in most cases by 1–1.5 m in 1995–2012 and 0.5–0.6 m in 2013–2022, while the corresponding surface area and volume values according to HYDROWEB data turn out to be underestimated.

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Section: Introductionmentioning

confidence: 63%

Water Dynamics and Morphometric Parameters of Lake Sevan (Armenia) in the Summer–Autumn Period According to Satellite Data

Ginzburg,

Kostianoy,

Sheremet

et al. 2024

Remote Sensing

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“…The results obtained by a multi-temporal UAV data analysis with ultra-high spatial resolution underlined the presence of flooded sites which, in time, led to the rapid degradation of the lagoon habitat. This intensified the lake eutrophication and provoked hazardous algal blooms, thus creating favourable conditions for phytoplankton development, as demonstrated by recent studies in the literature [18,25]. Furthermore, the increase of the water level induced a non-uniform erosion and sediment accumulation phenomenon along the shores, which caused the fragmentation of important habitats and lead to their disappearance.…”

Section: Discussionmentioning

confidence: 95%

A Preliminary Analysis of Anthropogenic and Natural Impacts on a Volcanic Lake Ecosystem in Southern Italy by UAV-Based Monitoring

Mirauda

Padula²,

Mirauda

et al. 2022

IJERPH

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Lakes play an important role in providing various ecosystem services. However, stressors such as climate change, land use, or land-cover change threaten the ecological functions of lakes. National and international legislations address these threats and establish consistent, long-term monitoring schemes. Remote sensing techniques based on the use of Unmanned Aerial Vehicles (UAV) have recently been demonstrated to provide accurate and low-cost spatio-temporal views for the assessment of the ecological status of aquatic ecosystems and the identification of areas at risk of contamination. Few studies have been carried out so far on the employment of these tools in the monitoring of lakes. Therefore, high-resolution UAV surveys were used to analyse and evaluate natural and anthropogenic impacts on the habitat status of a volcanic lake in a protected area. Five UAV flights took place during a year-long cycle (November 2020 to November 2021) in a volcanic lake located in southern Italy. For each flight performance, an orthomosaic of georeferenced RGB images was obtained, and the different features of interest were monitored and quantified using automated processing in a GIS environment. The UAV images made it possible not only to estimate the flooded shores but also to detect the impact of human-made structures and infrastructures on the lagoon environment. It has been possible to observe how the rapid changes in lake-water level have led to the submersion of about 90.000 m2 of terrain in winter, causing the fragmentation and degradation of habitats, while the connectivity of the natural ecosystem has been threatened by the presence of the road around the lake. The proposed methodology is rather simple and easily replicable by decision makers and local administrators and can be useful for choosing the best restoration interventions.

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“…Monitoring of the ecological state of the ecosystem of Lake Sevan (1900m) is estimated by the hydrobiont communities, which are indicators of trophic state (Hambaryan et al, 2018;Sakharova et al, 2020). Lake Sevan is located in the Gegharkunik Province in eastern part of the Republic of Armenia.…”

Section: Methodsmentioning

confidence: 99%

Changes in the horizontal development of phytoplankton of the littoral of Lake Sevan (Armenia) in conditions of water level fluctuations

Համբարյան¹,

Khachikyan²,

Ghukasyan³

2020

LFWB

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Horizontal and Vertical Distribution of Phytoplankton in the Alpine Lake Sevan (Armenia) during the Summer Cyanoprokaryota Bloom

Cited by 15 publications

References 11 publications

Water Dynamics and Morphometric Parameters of Lake Sevan (Armenia) in the Summer–Autumn Period According to Satellite Data

Water Dynamics and Morphometric Parameters of Lake Sevan (Armenia) in the Summer–Autumn Period According to Satellite Data

A Preliminary Analysis of Anthropogenic and Natural Impacts on a Volcanic Lake Ecosystem in Southern Italy by UAV-Based Monitoring

Changes in the horizontal development of phytoplankton of the littoral of Lake Sevan (Armenia) in conditions of water level fluctuations

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