scholarly journals Structure and functioning of phytoplankton in the Neva estuary in 2011–2016

2020 ◽  
Vol 324 (1) ◽  
pp. 162-174
Author(s):  
V.N. Nikulina ◽  
M.S. Golubkov

Long-term observations (since 1982), which had been carried out in the Neva River estuary, have shown that in 2011–2016 the general nature of distribution, species composition and abundance of phytoplankton differed from those that were recorded earlier. The greatest changes are noted in the central part close by northern coast of the Neva Bay. With observed eutrophication in the Neva Bay (st. 12) and in the eastern part of the Gulf of Finland (st. 19), different groups of algae dominated in the summer phytoplankton (late July – early August). The main mechanism regulating the species composition of phytoplankton were hydrological conditions observed in different parts of the estuary. Also Shallow water, wind activity, oxygen deficiency and temperature stratification, nutrient supply were favorable conditions for development of chlorococcal green, cryptophyte, euglenic and other algae groups. With a high Shannon index (3.8–4.0) in the Neva Bay, the largest share to the total biomass was given by chlorococcal algae. In the resort area of the Gulf of Finland at the end of July – early August, direct temperature stratification was usually established, with enough nutrients creating conditions for the development of stagnophilic planktonic algae with a predominance of cyanobacteria in the epilimion. Here, more often, were periods of surface “blooms”. For the most eutrophied areas of the Neva Bay and the inner estuary the average structural, functional, and relative indicators of plankton were compared with average values for the entire water area. The main characteristics of phytoplankton: biomass, primary production, chlorophyll concentration and total phosphorus content in the northern zone of the Neva Bay, were 2–3 times higher than the average values on the Gulf. The species composition of algae corresponded to a sufficiently high trophic state. In the resort area of inner estuary of the Gulf of Finland (st. 19), the observed mean values also slightly exceeded the average values for the estuary, but the relative indicators differed little from those calculated for the rest of the water area. The structural and functional characteristics of phytoplankton indicated that during eutrophication in different parts of the estuary, in Summer, conditions wer favorable to promote the development of different groups plankton algae.

Author(s):  
N Derugina ◽  
N Derugina ◽  
А Grigoriev ◽  
A Grigoriev ◽  
Дарья Рябчук ◽  
...  

This project defines the pre-industrial quantities of heavy metals in sediment sequences of the Late Holocene from the Eastern Gulf of Finland. A comparative analysis reveals differences and similarities in the current concentrations of heavy metals in bottom sediments and pre-industrial levels. It is found that the maximum concentrations of heavy metals in the bottom sediments of the Gulf of Finland and Neva Bay occurred in the period of 1950-1990. Since the 1990s, the trend has been a slow decline in the contamination levels; however, the concentrations of some heavy metals in bottom sediments remain high.


Author(s):  
Nataliya B. Balashova ◽  
Grigorii A. Kiselev

The biological method of water quality analysis, for the first time, was applied in Russia during the examination of Neva Bay of the Gulf of Finland in the Baltic Sea by Wislouch S.M. Neva River was a source of drinking water in St. Petersburg and, at the same time, a discharge for all city drains. As a result, it became hazardous to health, being a source of various diseases, especially cholera. From August 1911 to September 1912 pollution studies of the Bay were made to solve the question - where to send the treated waste water of the future sewage system of St. Petersburg. In total, 37 trips were made during this time, 510 samples were taken, including 375 plankton samples and 35 benthic samples. Wysłouch S. M. gave an overview of objects collected at 265 stations located in the area of Neva Bay - from estuary of Bolshaya Neva to Kronstadt, along the southern coast of the Bay and partially along the Northern coast. He brought a list of algae, including 97 species: Algae Cyanophyceae (writing all taxa retained on original source) – 17 species, Flagellata – 19 species, Peridineae – 1, One – 30, Conjugatae – 2, Diatomaceae – 28 species, Fungi (1), Bacteria (17), Protozoa (28), Rotatoria (17). Taking into account the algae and other organisms saprobity indices, areas with different degrees of contamination were identified. All the data was put on map of the Gulf. The most heavily polluted area was the Sea channel, and the area between the Lisij Nos and Kronstadt was the cleanest.


Trudy VNIRO ◽  
2020 ◽  
Vol 179 ◽  
pp. 149-163
Author(s):  
O. A. Liashenko ◽  
A. P. Pedchenko ◽  
O. N. Susloparova

The technogenic transformation of the ecosystem of the southeast part of Luga Bay water area (the second bay of the Baltic Sea) where Ust-Luga commercial seaport situated was determined by longstanding dredging, dumping and other types of anthropogenic impact. The development of phytoplankton as the main primary production former and the base of food reserve for aquatic biological resources was investigated during the monitoring of aquatic biological resources of the Luga Bay which was held due to the seaport construction. The investigation of phytoplankton content and development took part in the main seasons of the ice-free period of 2005–2018 in the water areas of dredging, damping, and adjacent areas. The maximum values of the phytoplankton abundance and biomass were detected in spring. The main part of biomass was formed by diatoms and dinoflagellates. The summer biomass mainly was lower than in spring and the proportion of cyanoprokaryotes (in some years also cryptophytes and green) increased. In autumn the biomass decreasing was continued, cyanoprokaryotes and cryptomonads dominated. The quantitative indicators of phytoplankton development were varied from year to year in all seasons of 2005–2018 but they kept in frames of values which previously observed for the water area of the Luga Bay. The influence of the Gulf of Finland water warming on phytoplankton development was not traced. The certain differences between the quantitative development and composition of the dominant phytoplankton complex on the water areas of dredging, damping, and adjacent areas weren’t observed. The average phytoplankton biomass for the ice-free period in the most part of years corresponds to the mesotrophic state of the Luga Bay water area. There was not a significant impact of dredging and dumping on the phytoplankton of the Luga Bay which indicates the stable state of its ecosystem primary producer and the preservation of the productional resource of the fish food base.


Author(s):  
Alexey Osipov ◽  
Georgy Osipov ◽  
Vasily Kovyazin

Biogenic pollution of water bodies and their eutrophication is one of the most serious environmental problems of our time. One of the sources of water pollution with biogenic substances is forests, which belong to the background sources of biogenic load. Currently available methods for assessing the removal of nutrients from the forest vegetation cover do not provide the desired results, which causes an urgent need for their improvement. This article describes the method developed by the authors of geoinformation modeling of removal of biogenic substances from the forest vegetation cover to water bodies, taking into account the spatial distribution of vegetation in the catchment area, its species composition and absorption of biogenic substances during their migration. The Eastern part of the Gulf of Finland was adopted as the object of testing of the developed method. this is due to the fact that eutrophication processes are actively manifested within its water area. The volume of the background biogenic load on the Gulf of Finland, formed during the decomposition of the fall of the natural vegetation cover in the catchment area, was determined based on the specific removal of biogenic substances from plant communities and their absorption during migration “plant community — water object”. The total background biogenic load on the eastern part of the Gulf of Finland, formed as a result of decomposition of natural vegetation cover, was 170.21 t/year for the northern catchment for nitrogen, 12.14 t/year for phosphorus, and 207.31 t/year for the southern catchment for nitrogen , and 15.68 t/year for phosphorus. The data obtained do not contradict the results of other authors who study the background biogenic load on the Gulf of Finland. The method can be effectively used in the development of measures to reduce the nutrient load on water bodies and planning of economic activities in catchments.


Algologia ◽  
2021 ◽  
Vol 31 (4) ◽  
pp. 382-389
Author(s):  
S.I. Genkal ◽  
◽  
I.S. Trifonova ◽  

This scanning electron microscopy study of phytoplankton from the Neva Bay and analysis of valve images from S.I. Genkal’s iconotheka have provided new data on centric diatoms of the Neva Bay. Representatives of the genera Aulacoseira scalaris and Stephanodiscus lacustris, new to the flora of the Bay, have been identified. The systematic position and distribution of 14 species and varieties of Centrophyceae from the genera Aulacoseira, Conticribra, Cyclostephanos, Ellerbeckia, Handmannia, Pantocsekiella, Stephanodiscus, Thalassiosira have been refined and specified. The species composition of the class Centrophyceae of the Neva Bay has been expanded. Now it includes 42 species and varieties from 17 genera.


2020 ◽  
Author(s):  
Taavi Liblik ◽  
Germo Väli ◽  
Inga Lips ◽  
Madis-Jaak Lilover ◽  
Villu Kikas ◽  
...  

Abstract. Stratification plays an essential role in the marine system. The shallow mixed layer is one of the preconditions for the enhanced primary production in the ocean. The general understanding is that the mixed layer is well deeper than the euphotic zone in the Baltic Sea during winter. In this work, we demonstrate the wintertime stratification is a common phenomenon in the Gulf of Finland. Shallow haline stratification at the depth comparable to the euphotic zone depth forms in late January–early February. Stratification is evoked by the positive buoyancy flux created by the westward advection of riverine water along the northern coast of the gulf. Fresher water and haline stratification appeared approximately one month later in the southern part of the gulf. The phenomena can occur in the whole gulf and also without ice. Chl a concentration and phytoplankton biomass in winter can be comparable to mid-summer. The limiting factor for phytoplankton bloom in winter is likely insufficient solar radiation.


Author(s):  
N Derugina ◽  
N Derugina ◽  
А Grigoriev ◽  
A Grigoriev ◽  
Дарья Рябчук ◽  
...  

This project defines the pre-industrial quantities of heavy metals in sediment sequences of the Late Holocene from the Eastern Gulf of Finland. A comparative analysis reveals differences and similarities in the current concentrations of heavy metals in bottom sediments and pre-industrial levels. It is found that the maximum concentrations of heavy metals in the bottom sediments of the Gulf of Finland and Neva Bay occurred in the period of 1950-1990. Since the 1990s, the trend has been a slow decline in the contamination levels; however, the concentrations of some heavy metals in bottom sediments remain high.


Author(s):  
Evgeny A. Zakharchuk ◽  
◽  
Vladimir N. Sukhachev ◽  
Natal'ia A. Tikhonova ◽  
◽  
...  

The characteristics of storm surges in different regions of the Gulf of Finland in the second half of the XX and the beginning of the XXI centuries were investigated on the basis of tide gauge measurements of sea level, instrumental observations of the wind and data from the reanalysis of meteorological fields. A criterion for identifying storm surges, taking into account spatial changes in their intensity, is proposed. The results indicate that depending on the year and the location of the station, the number of storm surges varies in the Gulf of Finland in a wide range: from 0 - 1 to 16 - 52 cases per year. The average duration of storm surges varies from 6.7 to 9.0 hours, and the maximum reaches 26 to 96 hours. Shown that in recent decades, in most regions, there has been a tendency towards a decrease in the number of storm surges, their dispersion and sea level maximum. The distributions of the probabilities of wind and atmospheric pressure during storm surges are given. Estimates of two-dimensional probability densities indicate that during storm surges, winds blowing from the west and southwest with speeds of 4-13 m / s are most likely. At the northern coast and at the top of the bay, the most probable values of atmospheric pressure during storm surges are 995 hPa. On the southern coast of the Gulf of Finland, atmospheric pressure values of 1005 - 1015 hPa are most likely. The results obtained indicate that the atmospheric pressure over the Gulf of Finland during storm surges is not very low. This is due to the fact that the trajectories of the centers of cyclones causing storm surges pass north of the Gulf of Finland. Analysis of meteorological information also showed the presence of significant negative trends in interannual variations in the dispersion of the horizontal atmospheric pressure gradient, average values and maximums of wind speed. It is concluded that the revealed changes in the characteristics of storm surges are associated with a decrease in the intensity of cyclogenesis in the atmosphere over the Baltic Sea in recent decades.


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