Coastal Vegetation in the Biotopes of the Estuaries of the White Sea and the Cheshskaya Bay of the Barents Sea

Coastal Vegetation in the Biotopes of the Estuaries of the White Sea and the Cheshskaya Bay of the Barents Sea | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Coastal Vegetation in the Biotopes of the Estuaries of the White Sea and the Cheshskaya Bay of the Barents Sea Dmitry Moseev, Andrei Leshchev, Tatyana Parinova, Alexey Volkov, and 3 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-6564393/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted 7 You are reading this latest preprint version Abstract The halophytic vegetation of the White and Barents Seas coasts of the Arctic Ocean is diverse, since it is formed under heterogeneous conditions under the influence of the ocean and land. Currently, little is known about the distribution of phytocenoses in saline biotopes on the White and Barents Seas coasts. The obtained picture of the halophyte vegetation structure will help to understand the patterns of coastal phytocenoses distribution in the biotopes of the White and Barents Seas coasts. From the standpoint of the ecological-phytocenotic approach, 40 associations were identified on the coasts based on the similarity of the structure and composition of plant communities. Vegetation ordination, built by the metric scaling method, shows the correspondence of plant communities to certain types of biotopes: salt marshes, brackish marshes, beaches and dunes, saline lagoon lakes, tidal flats at the heads of estuaries. In biotopes of various types, halophytic vegetation phytocenoses are formed, different in composition and structure. The paper employs ordination analysis to provide first-ever classification of brackish marshes into hygrophytic and hygromesophytic (grass-rush) groups, thus enriching the overall classification of marsh biocenoses. The biotopes of salt marshes are distinguished by the greatest phytocenotic diversity, with 21 associations of seaside vegetation identified. The species composition and halophyte vegetation structure are similar in the biotopes of the arctic marshes of the Mezen Bay and the Cheshskaya Bay estuaries, but these communities differ significantly from the boreal-type marshes on the southeast coast of the Dvina Bay and Onega Bay. The plants living conditions of different ecological groups in the sea coasts communities are not the same. Obligate halophytes develop in stable water salinity and pH conditions. Facultative halophytes are able to live in environments with wide pH and salinity variability. biotopes halophyte vegetation marshes salinity pH Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Introduction The sea coasts halophytic vegetation represents a unique azonal structure of buffer zones, where aquatic (marine) and terrestrial-air habitats are combined (Adam 1991; Chapman 1964 ; De Leweus et al 1991; Sergienko 2008). The coastal phytocenoses development occurs on the accumulative sea shores: marshes and beaches, which are very long on the White Sea coast. Marsh is a low accumulative coast formed under the influence of tides by bringing suspended sediments and bed load into the tidal flat, covered with subaerial halophytic vegetation (Leontiev et al. 1975). Marshes are also considered as a special type of biocenoses at the boundary of sea and land environments, where representatives of halophytic phytocenoses, seaweeds, land and sea invertebrates, birds, and microorganisms are found (Backer 2014; Chapman, 1964 ). Structurally, any type of vegetation forms a phytocenosis – a plant community existing within the limits of one biotope. V. P. Sukachev gives the following definition of a phytocenosis: an aggregate of plants growing on a certain territory, organized as a result of struggle for existence between plants within given habitat conditions, and characterized by certain relationships with one another and environmental conditions (Sukachev 1972). B.M. Mirkin defines phytocenosis as a conditionally delimited area of a plant continuum representing a set of plant populations associated with the given habitat conditions and forming relationships within a more or less homogeneous complex of environmental factors or ecotope (Mirkin et al. 1989 ). One of the most essential features of the coastal vegetation consists in its being dominated by communities of halophytes, i.e. salt-tolerant plants that grow in soils or tidal areas periodically experiencing seawater influx. These communities form salt marshes, representing the most commonly occurring type of low-coast vegetation cover. The structural feature of any type of vegetation is phytocenosis - a plant community existing within one biotope. According to V.P. Sukachev, phytocenosis is interpreted as a set of plants in a certain area, organized by the struggle for existence between plants in accordance with environmental conditions and characterized by certain relationships both with each other and with environmental conditions (Sukachev, 1972). According to B.M. Mirkin: phytocenosis is a conditionally delimited section of the vegetation continuum, a set of plant populations connected by habitat conditions and relationships within a more or less homogeneous complex of environmental factors or ecotope (Mirkin et al., 1989 ). The most important feature of seashore vegetation is the predominance of halophyte communities - plants adapted to living conditions on saline soil and in the intertidal zone of seas periodically flooded with sea water. Such communities form salt marshes. This is the most typical type of vegetation cover of low sea shores. The White Sea coastal vegetation is currently well studied, its classifications are presented for the White Sea western coast (Babina 2002 ), in the Kanin Peninsula rivers mouths (Korchagin 1935; Moseev, Sergienko, 2020 ), for the Dvina Bay southeastern coast (Moseev, Sergienko 2017a), the Onega Bay (Moseev, Sergienko 2017b), the sea northern coast (Koroleva et al. 2011). Ecological series were built, reflecting the spatial structure of coastal vegetation on the "sea-land" gradient of the White Sea western coast (Sergienko 2013 ; Babina 2001; 2002 ), the southeastern coast (Sergienko 2013 ) and the east coast (Korchagin 1935; Moseev, Sergienko 2020 ; Moseev et al. 2021 ). The information about the Barents Sea coastal vegetation structure is known from the works of Koroleva N.E., Matveeva N.V., Lavrinenko O.V. (Koroleva et al. 2011; Matveeva, Lavrinenko 2011 ). The vegetation spatial structure descriptions of the Bering and Chukchi seas arctic coasts are presented in the work of L. A. Sergienko (Sergienko 2008). New data on the environmental factors (tides, salinity, and water pH) influence on the river estuaries phytocenoses have been obtained (Moseev et al 2022 ). The research of V. Chapman (Chapman 1964 ; 1972), Adam (Adam 1991) is devoted to the study of the impact of salinity, hydrological regime, and soils texture on marshes phytocenoses. The results of studying the spatial structure of halophyte vegetation on the coasts of Iceland and Canada were obtained (Thannheizer 1991; Thannheizer, Hellfritz 1989). There is still no information about strict regularities in the distribution of seaside phytocenoses in the White Sea habitats. Until recently, there was practically no information about the vegetation of the White Sea southeastern coast and the coastal vegetation of the Kanin Peninsula middle part. Until now, there is no information on strict regularities in the coastal phytocenoses distribution in the White Sea habitats. Existing studies have failed to address the distribution patterns shown by the phytocenoses inhabiting the coasts of the White and Barents Seas. By the example of the Barents Sea Pechora Bay, the first models of multivariate analysis of halophyte vegetation phytocenoses in different coastal biotopes were obtained (Moseev et al. 2021 ; Moseev et al. 2022 ). The distribution of plant associations in the White Sea littoral was built according to the salinity and pH factors influence (Moseev et al. 2022 ). The purpose of this work is to present information about the distribution of halophytic vegetation phytocenoses in the White Sea coast and Cheshskaya Bay’ coast of the Barents Sea biotopes and the impact of abiotic factors on the species composition of coastal phytocenoses. Materials and methods The analysis of the coastal vegetation was carried out on the basis of 357 geobotanical descriptions made from the White Sea western coast to the Barents Sea Cheshskaya Bay. It includes the following small rivers mouths and lagoons localities: the Keret River mouth in the Kandalaksha Bay, the Kyanda and the Tapshenga rivers mouths of the Onega Bay and the Sukhoe (Dry) Sea Bay of the south-east of the Dvina Bay, the Kuya river mouth of the Dvina Bay, the Chizha river mouth of the Mezen Bay, the Chesha river mouth of the Cheshskaya Bay of the Barents Sea. (Fig. 1 , Table 1 ). The main part of the work was carried out by geobotanical profiling method. Profiles were laid in the direction from sea to land. On each profile, geobotanical descriptions of vegetation were made on sample areas 3 × 3 m 2 in size in the habitats with homogenous conditions. The species composition, the total projective vegetation cover (PC), the partial projective cover for each species, the height of the tiers, the soil texture, and the influence degree of the sea water from tides and surges were determined on the sample areas. The geobotanical profiling method is recognized to be effective by many geobotanists in the study of vegetation cover of various types (Aleksandrova 1969; Whittaker 1980; Sergienko 2008). Coastal phytocenoses formed on marshes change from the coastline of the sea to the basic shore, which makes it possible to obtain ecological and dynamic series of vegetation. The ecological-dynamic series is understood as a continuous interconnected chain of phytocenoses in accordance with changing environmental factors (Whittaker 1980). The transition from one phytocenosis to another can be smooth (diffused) or abrupt, which is facilitated by direct-acting ecological regimes change (Aleksandrova 1969). Table 1 Hydrological Conditions in the White Sea Small Rivers Mouths River mouth or lagoon Mean tidal range, m Tidal flat types Tidal flats length in the river mouths, km Salinity at the sea boundary, ‰ Keret’ 1,7 Narrow salt marshes with silty and clay soils. Stony spits. 3,0 23,0 Tapshenga 2,0 Extensive brackish marshes with peaty and silty soils at the top of the estuary. Narrow strip of salt marshes at the estuary sea boundary. 3,5 19,3 Kyanda 2,5 8,0 25,0 Kuya 0,8 Narrow brackish marshes with sandy-muddy substrate 3,0 9,0 Chizha 6,0 Extensive salt marshes with silty and mud soils at the estuaries’ sea boundary. Brackish marshes in estuary heads. 20,0 26,0 Chesha 3,5 Extensive salt marshes with silty and clay soils at the estuaries’ sea boundary. Brackish marshes in estuary heads. 8,0 32,0 Sukhoe (Dry) Sea 1,0 In the deltas of the Kad and Mudyuga rivers there are extensive brackish marshes with peaty soils. Salt marshes with silty-sandy soils in the northern part. 3,0* 5,7** 9,2*** * Length for the mouths of the Kad and Mudyuga rivers. ** Salinity for the Cad river mouth. *** Salinity for the Bolshaya Nitsa river mouth in the northern part of the lagoon. The tidal range varies in the estuaries under study. V.N. Mikhaylov classifies tidal estuaries into microtidal with syzygial tide under 1.6 m, mezotidal with tide range between 1.6 m and 2.8, and macrotidal with tide range of more than 2.8 m (Mikhaylov, 1997). On the marshes, according to the shape of the coastal relief and depending on the tidal influence, several biotopes with specific vegetation cover and habitat conditions are distinguished (Leskov 1936 ; Babina 2002 ; Moseev et al., 2021 ): 1 – low-level marshes, twice a day covered by tidal waters, correspond to the lower boundary of the littoral upper horizon; 2 – marshes of the flooding middle level by syzygial tidal waters, correspond to the boundary of the littoral upper horizon and are located 20–50 cm above the low level; 3 – high-level marshes, located above the boundary of syzygial tides, flooded by storm surge waters, in the oceanological classification they belong to the supralittoral zone. The non-metric multidimensional scaling method was used for the ordination of geobotanical descriptions. The Hellinger distance statistical measure was used for clustering phytocoenoses in different biotopes. This method is well suited for assessing the structure of phytocoenoses where coverage can range from 1 to 80%. The method helps to avoid zero values, which is important for clustering monodominant coastal communities (Legendr, Gallagher, 2001). Manhattan distance coefficients were used to analyze the similarity of species composition in plant communities. Calculations were performed using the R language (R Core Team, 2019 ). The data were visualized with the ggplot2 package (Wickham, 2016 ). Geobotanical descriptions were matched to hydrological indicators of salinity and tide levels, measured at the hydrological stations in estuaries and lagoons. Semi-diurnal observations of the tides range were carried out using a measuring rod tied to the defined zero of the post. For salinity measurements, a portable IDS Meter (HACH) conductometer and a Multi 3420 (WTW) multiparameter multimeter were used. Water pH measurements were made with pH meters from Hanna and Multi 3420 from WTW. To describe the growing conditions of halophyte plants in coastal vegetation communities, the SpH Index was derived. It determines the dependence of species on salinity and the aquatic environment pH. The SpH index was calculated by using the formula: $$\:SpH=\frac{{S}_{0}}{S}\times\:\frac{pH-{pH}_{ср}}{{pH}_{ср}}\times\:100$$ , where S 0 – average salinity of the world’s ocean (34 psu), S – maximum observed salinity in community habitats in the high water of the tidal cycle, pH – рН of the community habitat water, pH ср – average рН water value in the habitats of all the communities under study. Results Coastal biotopes vegetation of the White and Barents Seas Coastal vegetation is heterogeneous in terms of biotope diversity, as it forms in ecotonal areas where the marine aquatic environment combines with land. The heterogeneity of coastal biotopes and their phytocoenoses can be assessed using a non-metric multidimensional scaling method. The graphic interpretation clearly reflects the various types of coastal biotopes, indicating differences in the influence of factors related to the impact of the sea and estuaries. The Figure 2 highlights areas with species lists of salt marshes, hydrophytic brackish marshes, cereal-sitnic brackish marshes, beaches, freshwater tidal drying areas at the tops of estuaries, shoals of the lower littoral and shallows of the upper sublittoral, and salt lakes, as well as saline lakes. Each of these habitat types differs in species composition and structure, as well as in the specific mechanical composition of the soils. Among the many factors that influence estuarine phytocoenoses, the main ones are: tides, storm surges, spring floods, salinity, pH, and substrate type. Tides are a crucial factor in the formation of coastal phytocenoses in the estuaries of the White and Barents Seas. Macrotidal estuaries are characterized by a significant diversity of phytocenoses, which distinguishes them from mesotidal and microtidal estuaries (Fig. 3a). Saline marshes and grass-sedge brackish marshes occupy the largest areas in macrotidal estuaries (Fig. 3b). Mesotidal estuaries are closely linked to macrotidal estuaries (Fig. 3a): extensive saline marshes form on the mouth marine bars, while expansive hydrophytic brackish marshes develop in the estuaries (Fig. 3b). Microtidal estuaries differ from macrotidal estuaries in that they have poorly expressed saline marshes. However, extensive areas of microtidal estuaries are occupied by hydrophytic brackish marshes, bringing them closer to mesotidal estuaries. Beaches are formed under the influence of surf at the marine boundary of any estuary. Narrow tidal flats develop at the heads of all estuaries. For mesotidal and microtidal estuaries, shoals of the lower littoral and shallow waters of the upper sublittoral have been identified. Salt marshes Salt marshes are the most widely represented ecotopes type in river mouths and lagoons on the White and Barents Seas coasts. As can be seen from Figure 2, they are different from other types of biotopes. They develop at the sea boundary of estuaries and in lagoons at water salinity from 15 to 30‰ and are covered with phytocenoses dominated by obligate halophytes. The biotope is formed by the influence of saline tidal waters and storm surges. Twenty-one associations were described in the composition of the salt marshes vegetation. The marshes tidal flats, flooded by the tide twice a day, are covered with associations communities such as Salicornietum pojarkovae, Salicornietum pojarkovae tripoliosum vulgarae, Caricetum subspathaceae triglochinosum maritimae, Caricetum subspathaceae potentillosum egedae, Caricetum subspathaceae subpurum, Bolboschoenetum maritimi, Bolboschoenetum maritimi juncosum gerardii, Eleocharitetum uniglumis triglochinosum maritimi, Glaucetum maritimae, Puccinellietum phryganodis, Tripolietum vulgarae puccinelliosum phryganodis, Triglochinetum maritimi, Triglochinetum maritimi subass. salicorniosum pojarkovae, Triglochinetum maritimi tripoliosum vulgarae. The mid-level salt marshes tidal flats are covered by associations communities such as Caricetum glareosae potentillosum egedae, Potentillosum egedae festucosum rubrae, Plantaginetum maritimae, Plantaginetum subpolarae, Sonchusetum humilis atriplexosum nudicaulis (App. Table 1). Salt marshes are better expressed in estuaries with macrotidal conditions. In the Chizha River estuary on the Mezen Bay coast, a broad phytocenoses diversity of salt marshes causes the vegetation high variegation. The marshes invasion begins with the obligate halophytes communities of Puccinellietum phryganodis association (PC ( total projective cover ) – 40–60%), occupying the marshes silty tidal flats at the estuary sea boundary. They are daily exposed to the tide at salinity of about 26‰, as they are under water for over three hours. The marshes tidal flats along the estuary coastline are covered with vegetation, flooded with tidal waters with salinity of 21–25 ‰. The thickets of Salicornia pojarkovae community (PC – 30–60%) are formed in micro-depressions. Closer to the basic shores silt-loam tidal flats are covered with vast communities of Cari с etum subspathaceae association (PC – 70–90%), developing with daily tidal floods, the obligate halophyte Stellaria humifusa is found here in abundance as well. The phytocenoses of Cari с etum subspathaceae potentillosum egedae association (PC – 70–95%) occupy tidal flats vast areas along the basic shores in the strip of syzygy tides. Plantaginetum subpolaris association communities (PC – 50–70%) are formed on the tidal troughs’ silty shores of mid-level marshes. In mesotidal estuaries the areas occupied by marshes decrease. In the mouths of the Kyanda and Tapshenga rivers on the Onega Bay southeastern coast, the invasion of silty foreshores begins with the settlement of pioneering monodominant Puccinellietum phryganodis association communities, area 2–4 m 2 , daily covered by the tide for about four hours at water salinity up to 25‰. Triglochinetum maritimi tripoliosum vulgarae (PC – 15–50%) association, formed by succulent obligate halophytes, succeeds Puccinellia communities on the silty-loamy foreshores of the lower layer marshes. They cover the foreshores areas up to 10 m 2 and are flooded by the tide over two hours daily at the water salinity about 23‰. From the right bank of the Kyanda river estuary the same ecotopes are occupied by Plantaginetum maritimae (PC – 20–30%) association communities; in the Tapshenga river estuary there are monodominant Eleocharitetum uniglumis (PC up to 80 %) communities. The listed above halophytic communities form a kind of microbelts of saline marshes coastal pioneer vegetation. In the direction to the basic shore the change of succulent halophyte vegetation is observed: Bolboschoenetum maritimi (PC – 50–90%) association phytocenoses form the second marshes overgrowth belt on the Onega Bay coast. They occupy large areas of the silty-loamy marshes foreshores in the tops of the Nimenga and Kyanda bays; their narrow bands penetrate 2-4 km up the estuaries with the daily tidal waters flooding at 15–25‰. The primary vegetation background of the mesotidal Keret river estuary (and Keret Bay) is formed by Triglochinetum maritimi (PC – 20–40%) and Eleocharitetum uniglumis triglochinosum maritimi (PC – 30–60%) associations communities, developing on the silty-loamy foreshores flooded by the tidal waters at 5–20‰ salinity. In the syzygial tides influence zone these communities are succeeded by Caricetum subspathaceae association, which occupies small areas on the marshes’ loamy foreshore. There Phragmitetum australis association communities can be also found, as those small areas are flooded by brackish waters (about 25‰ salinity). At the estuary head they give place to Hippuridetum tetraphyllae association at 5–10‰ water salinity. In the microtidal estuaries of the Dvina Bay southeastern part, including a shallow lagoon - the Sukhoe Sea Bay, salt marshes occupy even smaller areas due to the desalination of the waters of the large Northern Dvina river and small rivers the Kuya, the Mudyuga, the Kad, and the Bolshaya Nitsa. On the west coast monodominant Puccinellietum phryganodis association communities occur on the Sukhoe Sea sandy foreshores, daily covered by tidal sea waters. At the Bolshaya Nitsa river mouth and near the bay west shore Bolboschoenetum maritimi (PC – 30–70%) association halophyte communities develop on the silty foreshores, daily flooded by tidal waters at up to 10‰ salinity. On the Nikolskaya spit, where the salinity of the Sukhoe Sea bay surrounding waters reaches 15 ‰, Salicornietum europeaea, Triglochinetum maritimi associations communities develop. In some respects, the saltmarsh biotope is similar to grass-rush biotope of brackish marshes, which is due to the presence in its composition of relative halophytes, i.e. species resistant to mild to medium salinity of substrate. These include Alopecurus arundinaceus and Juncus gerardii . Brackish marshes Brackish marshes occupy large areas in the tops of river estuaries and on the shores of lagoons washed by waters with a salinity of 1 to 15 ‰. The vast biotope found in the White Sea, in turn, clearly shows occurrence of two structurally independent ecotopes: hydrophytic brackish marshes and cereal-sitnik brackish marshes. The bottom of low-lying marshes is formed by silt, sand and silty sand, that of middle marshes by peat deposits, and that of high marshes by loamy soils with thin sod layer. Hydrophytic brackish marshes are formed in the mesotidal estuaries of the Onega (Kyanda and Tapshenga) and microtidal estuaries of the Dvinsky Bay (estuaries of the rivers of the Dry Sea Bay - Bolshaya Nitsa, Kad, Mudyuga). In Figure 2 they are formed into a separate “cloud” from other phytocenoses, which indicates significant geomorphological and geobotanical differences of these communities from phytocenoses of other biotopes. These phytocenoses are formed under the influence of brackish tidal waters and are to a lesser extent affected by storm surges. However, observations indicate that spring floods play a significant role in their development. Freshwater floodwaters stagnate in the marsh, which promotes the germination of hydrophilic species that form phytocenoses. In the zone of the diurnal tide, the communities of hygrophytic marshes are formed by thickets of Phragmites australis . Along the gradient to the land in the syzygial tides and surges influence zone, in addition to Phragmites australis , facultative halophytes Alopecurus arundinaceus and Juncus gerardii , take part in their formation, as well as obligate halophytes Triglochin maritima, Stellaria humifusa , and Carex salina at the mouth of the Bolshaya Nitsa river . Eleocharis acicularis co-dominates in depressions, along the banks of small channels, on muddy tidal flats. Reedbeds play an important environment-forming role in the Sukhoe Sea bay, contributing to eutrophication, the coastline silting, and reducing the wave-built impact on the coast. Moving into the bay, they contribute to the leveling of the coastline, displacing halophytic communities at that. Rotting, reed waste forms a peat subsoil, the thickness of which increases on the marshes of the upper and middle levels of tidal flooding, where soil silting decreases. This type of vegetation forms reed shores, also known in the Baltic, Black and Azov seas (Rebassoo 1975; Ivanov et al. 2008; Moseev 2014). At the sea boundaries of the mouths of the Kuya, Mudyuga, Kad, and Bolshaya Nitsa rivers, communities of the Phragmitetum australis bolboschoenosum maritimi association (PC – 60–100%) develop, occupying silty tidal flats marshes, daily flooded by the tide at a water salinity of up to 5.2–10.0 ‰ (App. Table 3). On the upstream silty flats, they are superseded by reed thickets of the subassociation Phragmitetum australis subpurum (GPC 90-100%), forming an extensive belt along the estuarine shoreline and distributing from the low-lying flats to the high marshes. Here, the reedbeds play an important environmental role as contributors to eutrophication and accretion of silt along the shore, as well as mitigators of swash action. The vegetation cover of the mesotidal estuaries of the Kyanda and Tapshenga rivers in the southeast of the Onega Bay is similar to that one in the southeast of the Dvina Bay. Here, silty tidal flats of low-level brackish marshes are covered with communities of the Phragmitetum australis bolboschoenosum maritimi association occupying the same ecotopes. Upstream of the rivers, on low-level marshes silty tidal flats, they are succeeded by dense reedbeds of the Phragmitetum australis subpurum subassociation (PC – 90–100%), forming an extensive belt along the estuarine shoreline and spreading from low level drainages down to high level marshes. Reed thickets play an important habitat-forming role in the bay, contributing to eutrophication, siltation of the shoreline, and reduction of wave action on the shore. Such communities can develop both in brackish (1–20‰) and fresh waters of marshes up to ecotopic zones with transitional communities. Reeds also settles up the rivers to estuaries tops at the forests boundary, where there are prominent signs of swamp-formation with inclusions of sphagnum mosses. Reeds thickets, playing an environment-forming role on the marshes, as well as in the Sukhoe Sea, form the main vegetation aspect of the Onega Bay southern coast. Marshes occupied by reeds, in the Sukhoe Sea occupy a coastal zone more than 3 km wide up the rivers’ mouths and form a specific type of phytogenic shores called reed banks (Leontiev et al. 1975). The brackish marshes of the tidal zone are inhabited by monodominant phytocenoses of Bolboschoenus maritimus , which form here on low-lying flats the narrow strips exposed to a diurnal tide cycle. In Figure 2, they appear as a stand-alone “cloud” at the top and mainly depend on tidal processes. Exposure to the diurnal tidal cycle stimulates the growth of Bolboschoenus maritimus across extensive range with water salinity between 10‰ and 25‰. Contributing to the accumulation of suspended and entrained sediments, the thickets of Bolboschoenus maritimus cause major silting. In the Bolshaya Nitsa estuary and near the western shore of the bay, the halophytic communities of the association Bolboschoenetum maritimi (PC 30-70%) occur on silty flats exposed to tidal influxes of 10‰ salinity. The macrotidal estuaries of the Chizha and Chesha are home to brackish Cereal-sitnik marshes (Seaside meadows) . In Figure 2, they appear as a stand-alone “cluster” lying next to that of salt marshes. Such habitats are formed under the influence of storm surge waters. Their communities occupy areas near the waterline (intermediate marshes) and are influenced by tides. On the low marshes silty soils, facultative halophytes communities develop, of which the communities of the Alopecuretum arundinacei association (PC, 45–99%) are of great importance in the secondary marshes invasion; they form strips along the estuary bank line and on the loamy terraces tidal flats daily flooded by the tide. On loamy soils along tidal troughs, narrow strips form hygrophytic communities of the Alopecuretum arundinacei caricosum salinae association (PC, 35–80%). The dominant species Carex salina forms an overgrowth microbelt along tidal troughs on loamy substrates that are daily flooded, and higher is succeeded by Alopecurus arundinaceus microbelt. Small micro-depressions, flooded by syzygial tides, are occupied by the Juncosum gerardii association (App. Table 3). Hygrophilous communities give place to oligo- and poly-dominant communities of high-level coastal meadows from the Festucetum rubrae alopecurosum arundinacei ( PC – 80–100%) and Festucetum rubrae juncosum gerardii (PC – 80–100%) associations, which develop on loamy soils and occupy an area of tens of and even hundreds of square meters. At the mouth of the Kyanda River on old coastal ridges with sandy loamy soils in the surges influence zone, an association of Elytrigietum repentis was identified, where, besides Elytrigia repens, Sonchus humilis co-dominates in the lower layer. Tidal flats in the estuaries’ tops Structurally similar to brackish marshes are the tidal flats in the estuarine headwater region. Like hygrophytic brackish marshes, they experience 2 tides a day but are reached by saline tidal waters only rarely and highly infrequently. For this reason, here occur freshwater phytocenoses, which appear in this coastal vegetation ecological series as a closing element stretching from the estuaries’ marine boundary towards headwater region. Such communities form a "cluster" near hydrophytic brackish marshes, indicating similar living conditions. This fact is shown in the graphical interpretation of the ordination in Figure 2. However, these phytocenoses are formed under the influence of freshwater and are only occasionally affected by the brackish waters of storm surges. In the southeast of the Dvina Bay, the communities of sub-associations Phragmitetum australis scirposum lacustris (PC, 30–50%) and Phragmitetum australis petasitosum radistis occupy the narrow freshwater estuary tops. In the tops of all the rivers estuaries on the White Sea and Cheshskaya Bay coast, large sedge communities of the Caricetum aquatilis association are present, forming thickets on low-level silty tidal flats, common for fresh water bodies and streams, and in the southeast of the Dvina Bay, also communities of the Caricetum acutae association occur (App. Table 3). Salt lakes In Figure 2, this biotope represents a small “cluster” lying next to the sublittoral and saltmarsh biotopes, since halophyte communities occur here as well. They are formed as a result of rivers’ mouths channels change (loop-lakes) or in micro-depressions because of the soil reduction under the influence of tides and surges. Bottom sediments of salt lakes are silty soils. The water ponds (less than 100-200 m 2 in area) depth does not usually exceed 0.5 m. In the majority of the salt lakes marshes the most typical communities belong to Hippuridetum tetraphillae association (Table 3), they occupy the small lakes and their coasts with silty soils to the 10-30sm depth and sometimes cover the lakes complete water areas. They can develop at a significant salinity range change (5-30‰). Studies show that these communities do not depend much on the tides influence, since they do not dry out in low water. But since they have a narrow range of habitats, they are stenotopic. Ассоциация Hippuridetum tetraphillae association is present in the salt lakes along the entire White Sea coast. Hydrophyte communities of other associations, such as Myriophilletum sibirici, Potametum pectinati , can also develop in the marshes’ brackish lakes (App. Table 3). Shoals of the lower littoral Concentrating on the middle and lower levels of the littoral, the watte flats differ from marshes by their poorly developed vascular plant cover. In Figure 2, this biotope represents a small “cluster” lying next to the sublittoral and saltmarsh biotopes, since halophyte communities occur here as well. The lower littoral dries up completely only during syzygial ebbs. Here in silt-covered tide pools, occur hydrophytic communities of the associations Ruppietum maritimae and Zosteretum marinae (App. Table 3). They exist here in conditions of widely fluctuating water salinity of 10‰ to 30‰, but do not dry up completely during moderately high tides and are less susceptible to water level fluctuations during the tidal cycle compared to saltmarsh communities. The biotope of the lower littoral zone is represented by vast silty tidal flats (waddens), which are almost devoid of macrophyte vegetation. The lower littoral dries up completely only at syzygial tides. In littoral baths on silty tidal flats the hydrophyte communities of Ruppietum maritimae and Zosteretum marinae are formed (Table 3) in the conditions of the significant changes of the water salinity (10-30‰) and tides level fluctuations. We gave the description of such communities in the Keret river estuary and in the Sukhoe Sea bay in the south-east Dvina bay. In the direction to the land, the waddens are replaced by marshes – coastal areas, covered with halophytic vegetation, and which are the result of their genesis (Kaplin et al., 1991). Shallows of the upper sublittoral The bottom substrates of the upper sublittoral are mainly covered with macrophyte algae communities. Of the macrophyte plants in the White Sea, this biotope is characterized only by Zosteretum marinae association communities (App. Table 3), which form “underwater meadows,” as well as other sea weeds communities. Communities of the Zosteretum marinae association with the participation of brown algae Fucus vesiculosus occupy depths of 1-1.5 m in low water on silty bottoms along the entire coast of the estuary of the Keret river (Keret Bay). They are formed with significant changes in water salinity from 23 ‰ at the sea boundary of the estuary to 10 ‰ at its head at the maximum tide level. The seagrass Zostera marina develops here under the halocline influence, due to which it inhabits the estuary areas with colder and saltier waters compared to the foreshores. Beaches The beaches of the White Sea coast stretch out for long distances. The phytocenoses of this biotope differ significantly in species composition and the impact of abiotic factors from the marshes phytocenoses (Fig. 2 (section 8)). Beaches are formed under the influence of waves and wind. This factor of influence distinguishes them from swamps. Tides and surges play a negligible role in their formation. The vegetation of the beaches on the White and Barents Seas coasts is rather monotonous. It contains 4 associations: Leymetum arenarii honckenyosum diffusae, Leymetum arenarii latirosum japonici, Leymetum arenarii plantaginosum maritimae (App. Table 4) . The closest to the coastal line are the communities of Leymetum arenarii honckenyosum peploidis association, they occupy the coastal ridges and their slopes facing the sea. In the White Sea on the sandy coastal ridges very close to the Sukhoe (Dry) Sea Bay coastal line Leymetum arenarii plantaginosum maritimae communities were found. Coming close to the basic shores one can observe that Leymetum arenarii honckenyosum peploidis association communities give place to Leymetum arenarii lathyrosum japonici association , which communities cover distant from the coastline sandy coastal ridges and dunes. The vegetation owes its homogeneity to the communities being dominated mostly by 3 psammophytic species: Leymus arenarius, Honckenya peploides, Lathyrus aleuticus . Some of these communities often include nitrophiles, which dominate due to the local accumulations of seaweed: Atriplex nudicaulis, Atriplex litoralis, Atriplex praecox, Plantago maritima, Glaux maritimus . Occurring also on marshes, and as can be seen from their location in Figure 2, these species make the biotopes under study similar in terms of composition of their communities. Salinity and pH of the water are important factors influencing the coastal plants growth in the biotopes of the littoral zone. Indexing of both factors shows that facultative halophytes can live with significant variability in salinity and pH, forming communities on brackish marshes, but also growing in salt marshes biotopes (Fig. 5). These are 25 species of vascular plants: Triglochin palustris, Agrostis stolonifera, Alopecurus arundinaceus, Leymus arenarius, Puccinellia distans, Carex recta, Carex saxatilis, Eleocharis uniglumis, Schoenoplectus tabernaemontani, Juncus arcticus, Juncus gerardii, Ranunculus hyperboreus, Cochlearia arctica, Parnassia palustris, Lathyrus aleuticus, Hippuris ´ lanceolata Angelica litoralis, Ligusticum scoticum, Cenolophium denudatum, Armeria scabra, Polemonium boreale, Crepis nigrescens, Lactuca tatarica, Tephroseris palustris, Sonchus humilis, Tripleurospermum maritimum. Obligate halophytes (euglophytes), tending to biotopes of salt marshes, upper sub-littoral and lower littoral, salty lagoon lakes, are steno-bionts, as they grow in the conditions of small water salinity and pH fluctuations. These are 31 types: Zostera marina, Ruppia maritima, Triglochin maritima, Agrostis straminea, Calamagrostis deschampsioides, Dupontia psilosantha, Puccinellia coarctata, Puccinellia maritima, Puccinellia phryganodes, Puccinellia pulvinata, Puccinellia capillaris, Carex glareosa, Carex mackenziei, Carex maritima, Carex salina, Carex subspathacea, Bolboschoenus maritimus, Blysmus rufus, Atriplex nudicaulis, Salicornia pojarkovae, Stellaria humifusa, Honckenya peploides subsp. diffusa, Potentilla egedii, Hippuris tetraphylla, Primula finmarchica, Glaux maritima, Plantago maritima, Plantago subpolaris, Plantago schrenkii, Arctantemum hulteni, Tripolium pannonicum. In the conditions of low pH variability, tolerant to salinity glycophytes live, prevailing on brackish marshes and in brackish lagoon lakes, there are 14 species: Potamogeton pectinatus, Arctophila fulva, Calamagrostis neglecta, Elytrigia repens, Festuca rubra, Festuca arenaria, Festuca richardsonii, Phragmites australis, Eleocharis acicularis, Allium schoenoprasum, Rumex aquaticus, Callitriche hermaphroditica, Empetrum hermaphroditum, Myriophyllum sibiricum . However, as the research shows these plants are able to tolerate rather significant salinity fluctuations. Discussion The similarities and differences between the coastal vegetation of the estuaries of the White Sea and the Cheshskaya Bay are well reflected in the graphical interpretation of their communities in Fig. 6 . The coastal vegetation of the mesotidal and microtidal estuaries of the Dvina and Onega bays is the most similar (Fig. 6 ). Here, the largest areas are occupied by brackish marshes with specific communities of Phragmitetum australis associations, where mainly the freshwater plant species prevail, however, the hygrophile halophytes are also present. Such communities develop in a wide range water salinity change in river estuaries on marshes of a mid-level tide influence. The main aspect of the vegetation cover of the low-level marshes is created by Bolboshoenetum maritimi association communities. At that, the communities with prevailing succulent obligate halophytes from the associations Triglochinetum maritimi, Glaucetum maritimae, Salicornietum pojarkovae, Plantaginetum maritimae mainly occupy small areas at the estuaries’ sea boundaries. Hydrophyte Zostera marina forms communities in the aquatic environment of the lower sublittoral. The vegetation of the Chizha river, which flows into the Mezensky Bay, and the Chesha river, which flows into the Cheshskaya Bay estuaries, differs significantly from the Dvina and Onega bays vegetation (Fig. 3). Here, on the sea boundary, the main areas of silty-loamy tidal flats of the low and mid-level marshes are occupied by salt marshes with characteristic communities of obligate halophytes from Caricetum subspathaceae, Caricetum subspathaceae potentillosum egedii, Caricetum glareosae, Plantaginetum subpolaris, Puccinellietum phryganodis, Salicornietum pojarkovae, Triglochinetum maritimi associations. The brackish marshes biotopes are located at the river mouths heads. The low-level brackish marshes tidal flats are covered with the communities of Alopecuretum arundinacei, Alopecuretum arundinacei caricosum salinae associations. High-level marshes tidal flats are covered by the communities Festicetum rubrae juncosum gerardii, Festucetum rubrae alopecurosum arundinacei associations. At the Keret river mouth of the Kandalaksha Bay the hygrophilous communities of succulents Eleocharitetum uniglumis triglochinosum maritimi, and Triglochinetum maritimi prevail, which places the Keret river estuary vegetation close to the one of the Chesha river estuary. The aquatic environment of the lower littoral is characterized by communities of Ruppietum maritimae , and of the sublittoral by Zosteretum marinae, which makes the vegetation structure of the Keret river similar to the Dvina Bay southeastern coast. Graphical interpretation of biotopes by oceanic zones shows a significant similarity between the coastal vegetation of the middle and upper littoral and supralittoral. These zones include biotopes formed under the influence of tidal waters and storm surges: mid- and low-level salt marshes, mid- and high-level brackish marshes, saline lagoon lakes and beaches. Their communities occupy the largest areas on the seas coasts. The vegetation of the arctic salt marshes of the Mezen and the Cheshskaya Bays is close in composition and structure to the vegetation of the coasts of Iceland, southern Greenland, and northern Norway (Nordhagen 1954 ; Thannheiser 1975 ; 1991 ; Thannheiser, Willers T. 1988 ; Thannheiser, Hellfritz 1989 ). The similarity lies in the species composition of the associations Salicornietum pojarkovae, Caricetum subspathaceae triglochinosum maritimae, Caricetum subspathaceae potentillosum egedii, Caricetum subspathaceae subpurum, Glaucetum maritimae , Puccinellietum phryganodis, Tripolietum vulgarae puccinelliosum phryganodis, Triglochinetum maritimi, Triglochinetum maritimi salicorniosum pojarkovae, Triglochinetum maritimi tripoliosum vulgarae, Caricetum glareosae potentillosum egedii, Potentillosum egedii festucosum rubrae, and Plantaginetum subpolarae. Large areas occupied by the communities of Caricetum subspathaceae subpurum , Caricetum glareosae potentillosum egedii associations indicate the similarity with Chukchi and Bering Seas coasts (Sergienko 2008), including the Korf bay (Neshataeva et al. 2014 ). In general, the halophyte vegetation of the mouths of the Chizha and Chesha rivers on the Kanin Peninsula has many similar communities with the ones of the southeastern coast of the Barents Sea, described in the works (Matveeva and Lavrinenko 2011 ; Lavrinenko and Lavrinenko 2018 ). The brackish marshes of the southeast Dvina and Onega bays, which, according to the classification of V. Chapman, belong to the boreal type (Chapman 1960 ; 1964 ), show similarities with the coast of the Baltic Sea (Rebassoo 1975 ; Rebassoo 1987 ). But at the same time, due to the dominance of large macrophytes Phragmites australis, Bolboschoenus maritimus in the communities composition, their vegetation cover is similar even to the flood plains of the Azov Sea and the Black Sea estuaries (Golub 2017 ; Grechushkina et al 2011 ; Preislerová et al 2022 ). The salt marshes communities at the sea boundary of the rivers’ Sukhoe Sea Bay are similar to the communities of the sea coasts of Northern Norway (Nordhagen 1954 ). In its turn, the vegetation of the Keret river mouth in the Kandalaksha Bay is similar to other areas of the White Sea western coast (Babina 2002 ; Vekhov and Georgievsky 1984 ; Sergienko 2013 ). In addition, the salt marshes of the White Sea both the eastern and southeastern coasts have many similar communities with the northern coast (Koroleva et al. 2011). Eleocharitetum uniglumis association communities, widely spread in the Onega, Dvina and Kandalaksha bays, are also known on the coasts of the Baltic Sea (Siira 1987 ) and the Norwegian Sea (Thannheiser 1991 ). Hippuridetum tetraphillae association of salt lakes is widespread along the White Sea entire coast (Babina 2002 ; Koroleva et al. 2011; Moseev, Sergienko 2020 ). Its communities are known in the southeast of the Barents Sea (Matveeva, Lavrinenko 2011 , Moseev, Sergienko, 2020 , Moseev et al., 2022 ), on the shores of the Chukchi and Bering Seas (Neshataeva et al 2014 ; Sergienko 2008), the seas of North America (Nordhagen 1954 ). Communities of the upper littoral and lower sublittoral from the Zosteretum marinae association develop along the White Sea entire western coast (Vekhov 1984 ), locally along the northern (Bologna 1984) and western coasts of the seas of Europe (Wong et al. 2021 ), the Black and Azov Seas (Kalugina Gutnik 1975; Milchakova 1988 ; Sadogursky 1999), at the coasts of North America (Lopez-Calderon 2016), in the seas of the Far East (Kalita, Skriptsova 2018 ). Due to the dominance of the large grass Leymus arenarius and the creeping arctic-boreal species Honckenya peploides , the vegetation of the beach psammophyton is similar to the vegetation of the beaches of the coasts of Iceland and northern Norway (Thannheiser 1987 ; 1998 ). Conclusion By using the technique of metric multidimensional scaling, we have identified a total of seven types of biotopes occurring on the coast of the White Sea and the Chesha Bay, each with its own vegetation composition and structure – saltmarsh, brackish marsh, beach, salt lagoon lakes, lower-littoral watte flat, upper-sublittoral silt sand soil. These biotopes differ in vegetation, location within oceanic zones, soil mechanics, and tide height. The brackish marsh type has been found to comprise 2 clearly distinct biotopes: hygrophytic brackish marshes and cereal-sitnic brackish marshes. Salt marshes are the main biotope on the sea boundaries of the estuaries of the Mezen Bay and the Cheshskaya Bay, Kandalaksha Bay, where the water salinity reaches 15–32‰. The largest areas in the biotope are occupied by communities of Salicornietum pojarkovae, Caricetum subspathaceae potentillosum egedii, Caricetum subspathaceae subpurum, Puccinellietum phryganodis, Triglochinetum maritimi, Triglochinetum maritimi tripoliosum vulgarae, Caricetum glareosae potentillosum egedii, Plantaginetum maritimae, Plantaginetum subpolarae associations. Here brackish marshes distinctly classify into the following two biotopes: hygrophytic marshes and hygromesophytic (grass-rush) marshes. The hygrophytic brackish marshes occur within the Onega estuary and the southeastern sector of the Dvina Bay, where water salinity decreases to the range of 1–20‰. Vast areas within this biotope are occupied by the communities of the associations Bolboschoenetum maritime and Phragmitetum australis . The other biotope – hygromesophytic brackish marshes – occurs within the estuaries of the Mezen Bay and Chesha Bay. Here, the ecological niche of the boreal species Phragmites australis and Bolboschoenus maritimus is occupied by the Arctic boreal grass Alopecurus arundinaceus , which forms communities of the association Alopecuretum arundinacei on vast areas within headwater regions of the Chizha estuary and the Chesha estuary, whereas the vegetation of high marshes is formed by the of communities of Juncus gerardii and Festuca rubra , some including Alopecurus arundinaceus . In the estuaries of the Onega Bay and the Dvina Bay southeast, brackish marshes are formed due to a decrease in water salinity to 1–15‰. The largest areas in the biotopes are occupied by communities of Bolboschoenetum maritimi, Phragmitetum australis associations. In the rivers mouths of the Mezen Bay and the Cheshskaya Bay, brackish marshes with communities of the Alopecuretum arundinacei association are located on vast territories in the river estuaries heads. Salt lakes are home to the communities of the association Hippuridetum tetraphyllae , lower littoral to those of Ruppietum maritimae and upper sublittoral to Zosteretum maritimae . The narrow tidal flats in the headwater regions of the estuaries are covered with large sedge communities of the associations Caricetum aquatilis and Caricetum acutae . It is demonstrated, that the salt marshes communities dominated by obligate halophytes are stenotopic in terms of salinity. On the contrary, the brackish marshes communities covered with facultative halophytes and salinity-tolerant glycophytes are more eurytopic regarding the he salinity factor. The conducted research expands adds up to the information about the halophytic vegetation of the coasts of the White Sea and the Cheshskaya Bay. The azonal coastal vegetation includes rather rare communities that are very vulnerable to natural and anthropogenic changes in the abiotic environment, which requires the development of biomonitoring of their condition. Monitoring of the vulnerable phytocenoses must be carried out annually in the rivers’ mouths where marshes are formed. Many communities of the White Sea coast are rare, such is the association of Ruppietum maritimae , which requires their protection measures development, that is the annual monitoring of the dominant species Ruppia maritima population state, included in the bio-surveillance of the Red Book of the Arkhangelsk Region (2020). The technique of metric multidimensional scaling allows differentiating the biotopes with similar vegetation cover occurring on the accumulative shores. This approach can be applied to any marine coast, be it the Barents or the White Sea coast in the northern sector of the European continent, or the North or Baltic Sea that wash Central, Western and Northern Europe, since they are home to homogeneous biotopes. The structure and species composition of phytocenoses belonging to different types of biotopes reveal similarities and differences as to some of their elements and in the first place species composition. The salt and brackish marshes are often home to same species of halophytes and glycophytes, which are found even on beaches. This similarity indicates the unity of the accumulative shores in terms of vegetation, including species in the tidal zone, which form one single phytocenotic complex comprising the coastal halophytic vegetation. At the same time, given the biotope-specific dominant coastal species, there are certain differences. Declarations Funding The work was carried out within the framework of the state task topic No. FMWE-2024-0020/"Sedimentation in modern and ancient oceans - dispersed sediment and bottom sediments as geologic archives of climate change and natural systems in key areas of the World Ocean, Russian seas and the sea-land boundary region". Data availability All data generated or analyzed during this study are included in this published article and its supplementary materials. Code availability. Not applicable. Conflict of interest The authors declare no competing interests. Ethical approval The study was conducted in accordance with the ethical guidelines for wildlife research, and all necessary permissions were obtained from relevant authorities. Acknowledgements The work at the mouth of the Keret River in the Kandalaksha Bay was supported by the Botany and Plant Physiology Department of Petrozavodsk State University. 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(2008) Flora and vegetation of the coasts of the Russian Arctic and adjacent territories. Petrozavodsk. 225 p. Sergienko L.A. (2013) Composition and dynamics of the vegetation cover of the coasts of the Russian Arctic. Petrozavodsk, PETR GU Publishing House. 127 p. Siira J. (1987) On the vegetation and ecology of saline and brackish marshes in Finnmark (Norway). Aquilo. Ser. Botanical. 24, 15-36. Sukachev V.N. (1975) Selected works. Problems of phytocenology. Vol. 3. 542 p. Thannheiser D. (1975) Biobachtungen zur Kustlenvegetation auf der westlichen kanadischen Arctis-Archipel, Polarforschung . 45 (1), 1–16. Thannheiser D. (1987) Vergleichende ökologische Studien an der Küstenvegetation am Nordatlantik, Berliner geographische Studien. 25, 285-299. Thannheiser D. (1991) Die Kustenvegetation der arktischen und borealen Zone . Ber. d. Reinh.- Tuxen- Ges. Hannover. 3: 21–42. Thannheiser D. (1998)North Atlantic Coastal Vegetation. Kelletat (ed.) German Geographical Coastal Research, 222–233 Thannheiser D., Willers T. (1988) Die Pflansengezellschaften der Salzwiessen in der Westichen Kanadischen Arctis. Hamburger Gepgrafische Studien Hf . 44, 207–222. Thannheiser D., Hellfritz K.P. (1989) Die Vegetation der Salzwiesen auf den Quenn Charlotte Islands (Westkanada), Essener Georg. Arbeiten. Paderborn. Bd. 17, 153–17 Wickham H. (2016) ggplot2: Elegant Graphics for Data Analysis. Springer-Verlag New York. https://doi.org/10.1007/978-3-319-24277-4_9 Whittaker R.H. (1975) Communities and ecosystems. New York. 327 p. Vekhov N. V. Georgievsky A. B. (1984) Meadows of the Kovdsky Peninsula and Veliky Island. Botanical research in the reserves of the RSFSR. M., 50-66. Vekhov N.V. (1992) Zostera marina L. of the White Sea. Moscow: Publishing House of Moscow State University. 143 p. Wong M.C., Vercaemer B.M., Griffiths G. (2021) Response and recovery of eelgrass (Zostera marina) to chronic and episodic light disturbance. Estuaries and Coasts. 4 (2): 312-324. Additional Declarations No competing interests reported. Cite Share Download PDF Status: Under Review Version 1 posted Editorial decision: Revision requested 06 Feb, 2026 Reviews received at journal 09 Jun, 2025 Reviewers agreed at journal 20 May, 2025 Reviewers invited by journal 19 May, 2025 Editor assigned by journal 19 May, 2025 Submission checks completed at journal 30 Apr, 2025 First submitted to journal 30 Apr, 2025 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-6564393","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":459317659,"identity":"19088b90-1448-4951-9407-9174eca442f9","order_by":0,"name":"Dmitry Moseev","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA5ElEQVRIie2RsQqCUBSGTwjXhqM2KkLPYFxoSXoWJXBycHJNCJwk13oLoRcQDtQizYZLD9DWEhWU1W53DLrfcODA+fh/OAASyS+iMCgBzKGhJu3GxBWXW1kpqnyuAr+oPUHF2TGfoiv1isNpdI5i10/syulWiJW0XpJiNSG3V/uAgx52K9ZCTUjLiOlN6NhaSkNAFFMQDhW/aekDvyqG0hbDS2AOahy3KeX3lFbxSEtcx8qCeIL7GWfIok6FGVt+xrs5z1XaNBhP/RyVolN500tfs//pI/ZNuL+GehQ7lkgkkr/jCXpEQQhYp5zAAAAAAElFTkSuQmCC","orcid":"","institution":"Shirshov Institute of oceanology, Russian academy of sciences","correspondingAuthor":true,"prefix":"","firstName":"Dmitry","middleName":"","lastName":"Moseev","suffix":""},{"id":459317665,"identity":"d6a483d8-4a9c-4bdf-a365-7a9c7a6e1a0d","order_by":1,"name":"Andrei Leshchev","email":"","orcid":"","institution":"Shirshov Institute of oceanology, Russian academy of sciences","correspondingAuthor":false,"prefix":"","firstName":"Andrei","middleName":"","lastName":"Leshchev","suffix":""},{"id":459317666,"identity":"079b23db-de8f-4231-bfad-2b0d52fc2040","order_by":2,"name":"Tatyana Parinova","email":"","orcid":"","institution":"Northern (Arctic) Federal University","correspondingAuthor":false,"prefix":"","firstName":"Tatyana","middleName":"","lastName":"Parinova","suffix":""},{"id":459317667,"identity":"80693919-5140-423c-ae78-c3d65c4d2ffc","order_by":3,"name":"Alexey Volkov","email":"","orcid":"","institution":"Northern (Arctic) Federal University","correspondingAuthor":false,"prefix":"","firstName":"Alexey","middleName":"","lastName":"Volkov","suffix":""},{"id":459317668,"identity":"e16d0c39-85cc-485b-be15-468e76030bce","order_by":4,"name":"Lyudmila Sergienko","email":"","orcid":"","institution":"Petrozavodsk State University","correspondingAuthor":false,"prefix":"","firstName":"Lyudmila","middleName":"","lastName":"Sergienko","suffix":""},{"id":459317671,"identity":"e29915ae-8ecf-4c6f-a4e6-002f3fabfd57","order_by":5,"name":"Igor Miskevich","email":"","orcid":"","institution":"Shirshov Institute of oceanology, Russian academy of sciences","correspondingAuthor":false,"prefix":"","firstName":"Igor","middleName":"","lastName":"Miskevich","suffix":""},{"id":459317673,"identity":"218bba97-a245-45ba-a9e8-57f752f6c60f","order_by":6,"name":"Natalya Makhnovich","email":"","orcid":"","institution":"Shirshov Institute of oceanology, Russian academy of sciences","correspondingAuthor":false,"prefix":"","firstName":"Natalya","middleName":"","lastName":"Makhnovich","suffix":""}],"badges":[],"createdAt":"2025-04-30 11:08:22","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-6564393/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-6564393/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":83240559,"identity":"84d615f1-88bd-478e-b1ea-c2ca96dbdc20","added_by":"auto","created_at":"2025-05-21 15:44:27","extension":"jpeg","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":233720,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eSchematic map of locations on the White Sea coast: Kr – mouth of the Keret River, Tp – mouth of the Tapshenga River, Kn ­– mouth of the Kanda River, SM – Sukhoe (Dry) Sea Bay, Kuya – mouth of the Kuya River, Chz – mouth of the Chizha River, Chsh ­– mouth of the Chesha river\u003c/strong\u003e\u003c/p\u003e","description":"","filename":"floatimage1.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-6564393/v1/5afd1cbe86e3c90e573bf7eb.jpeg"},{"id":83239962,"identity":"473278d0-3c2f-48cc-bfd3-c5267c957273","added_by":"auto","created_at":"2025-05-21 15:36:27","extension":"jpeg","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":598951,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003ePrincipal coordinates analysis of species at biotops\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eNumbers indicate biotopes: 1 - salt marshes, 2 - hydrophytic brackish marshes, 3 - cereal-sitnic brackish marshes (seaside meadows), 4 - salt lakes, 5 - shoals of the lower littoral, 6 - shallows of the upper sublittoral, 7 - tidal drying areas at the tops of estuaries, 8 - beaches.\u003c/strong\u003e\u003c/p\u003e","description":"","filename":"floatimage2.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-6564393/v1/d8c0f959488aa3d68499c057.jpeg"},{"id":83239970,"identity":"2002dfcf-b3e8-45de-ac29-73e827116a72","added_by":"auto","created_at":"2025-05-21 15:36:28","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":274021,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eDistribution of phytocenoses in estuaries with different tidal magnitudes: a) ordination of coastal phytocenoses in estuaries with different tidal magnitudes, b) ordination of seaside phytocenoses in estuaries with different tidal magnitudes by biotopes\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNote: names of biotopes are given in Fig. 2\u003c/p\u003e\n\u003cp\u003e\u003cbr\u003e\u003c/p\u003e","description":"","filename":"3.png","url":"https://assets-eu.researchsquare.com/files/rs-6564393/v1/319a0be886f2f8fe3416e83a.png"},{"id":83239983,"identity":"2191bebc-db77-4c36-9fa4-a679c04d86fc","added_by":"auto","created_at":"2025-05-21 15:36:29","extension":"jpeg","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":135482,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eDistribution of halophytes with different water salinity and pH indicators\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eBlue dots – obligate halophytes, red dots – facultative halophytes, green dots – glycophytes, tolerant to salinity\u003c/p\u003e","description":"","filename":"floatimage5.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-6564393/v1/ccee2160fdd9a00bf4060fea.jpeg"},{"id":83239973,"identity":"0447b530-ba33-487b-b16a-ed61ff04756f","added_by":"auto","created_at":"2025-05-21 15:36:28","extension":"jpeg","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":279316,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eGraphic interpretation of the vegetation similarity of the accumulative shores of the White Sea and the Cheshskaya Bays\u003c/strong\u003e\u003c/p\u003e","description":"","filename":"floatimage6.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-6564393/v1/30c64ca40500c96e553bf104.jpeg"},{"id":83242298,"identity":"393fde0a-7096-457e-bca6-9cc2776b8173","added_by":"auto","created_at":"2025-05-21 16:08:29","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":2663633,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-6564393/v1/9fc9e650-5c4a-4bea-bd22-fd8ee1480e42.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Coastal Vegetation in the Biotopes of the Estuaries of the White Sea and the Cheshskaya Bay of the Barents Sea","fulltext":[{"header":"Introduction","content":"\u003cp\u003eThe sea coasts halophytic vegetation represents a unique azonal structure of buffer zones, where aquatic (marine) and terrestrial-air habitats are combined (Adam 1991; Chapman \u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e1964\u003c/span\u003e; De Leweus et al 1991; Sergienko 2008). The coastal phytocenoses development occurs on the accumulative sea shores: marshes and beaches, which are very long on the White Sea coast. Marsh is a low accumulative coast formed under the influence of tides by bringing suspended sediments and bed load into the tidal flat, covered with subaerial halophytic vegetation (Leontiev et al. 1975). Marshes are also considered as a special type of biocenoses at the boundary of sea and land environments, where representatives of halophytic phytocenoses, seaweeds, land and sea invertebrates, birds, and microorganisms are found (Backer 2014; Chapman, \u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e1964\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eStructurally, any type of vegetation forms a phytocenosis \u0026ndash; a plant community existing within the limits of one biotope. V. P. Sukachev gives the following definition of a phytocenosis: an aggregate of plants growing on a certain territory, organized as a result of struggle for existence between plants within given habitat conditions, and characterized by certain relationships with one another and environmental conditions (Sukachev 1972). B.M. Mirkin defines phytocenosis as a conditionally delimited area of a plant continuum representing a set of plant populations associated with the given habitat conditions and forming relationships within a more or less homogeneous complex of environmental factors or ecotope (Mirkin et al. \u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e1989\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eOne of the most essential features of the coastal vegetation consists in its being dominated by communities of halophytes, i.e. salt-tolerant plants that grow in soils or tidal areas periodically experiencing seawater influx. These communities form salt marshes, representing the most commonly occurring type of low-coast vegetation cover.\u003c/p\u003e \u003cp\u003eThe structural feature of any type of vegetation is phytocenosis - a plant community existing within one biotope. According to V.P. Sukachev, phytocenosis is interpreted as a set of plants in a certain area, organized by the struggle for existence between plants in accordance with environmental conditions and characterized by certain relationships both with each other and with environmental conditions (Sukachev, 1972). According to B.M. Mirkin: phytocenosis is a conditionally delimited section of the vegetation continuum, a set of plant populations connected by habitat conditions and relationships within a more or less homogeneous complex of environmental factors or ecotope (Mirkin et al., \u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e1989\u003c/span\u003e). The most important feature of seashore vegetation is the predominance of halophyte communities - plants adapted to living conditions on saline soil and in the intertidal zone of seas periodically flooded with sea water. Such communities form salt marshes. This is the most typical type of vegetation cover of low sea shores.\u003c/p\u003e \u003cp\u003eThe White Sea coastal vegetation is currently well studied, its classifications are presented for the White Sea western coast (Babina \u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e2002\u003c/span\u003e), in the Kanin Peninsula rivers mouths (Korchagin 1935; Moseev, Sergienko, \u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e2020\u003c/span\u003e), for the Dvina Bay southeastern coast (Moseev, Sergienko 2017a), the Onega Bay (Moseev, Sergienko 2017b), the sea northern coast (Koroleva et al. 2011). Ecological series were built, reflecting the spatial structure of coastal vegetation on the \"sea-land\" gradient of the White Sea western coast (Sergienko \u003cspan citationid=\"CR42\" class=\"CitationRef\"\u003e2013\u003c/span\u003e; Babina 2001; \u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e2002\u003c/span\u003e), the southeastern coast (Sergienko \u003cspan citationid=\"CR42\" class=\"CitationRef\"\u003e2013\u003c/span\u003e) and the east coast (Korchagin 1935; Moseev, Sergienko \u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e2020\u003c/span\u003e; Moseev et al. \u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e2021\u003c/span\u003e). The information about the Barents Sea coastal vegetation structure is known from the works of Koroleva N.E., Matveeva N.V., Lavrinenko O.V. (Koroleva et al. 2011; Matveeva, Lavrinenko \u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e2011\u003c/span\u003e). The vegetation spatial structure descriptions of the Bering and Chukchi seas arctic coasts are presented in the work of L. A. Sergienko (Sergienko 2008). New data on the environmental factors (tides, salinity, and water pH) influence on the river estuaries phytocenoses have been obtained (Moseev et al \u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e2022\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eThe research of V. Chapman (Chapman \u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e1964\u003c/span\u003e; 1972), Adam (Adam 1991) is devoted to the study of the impact of salinity, hydrological regime, and soils texture on marshes phytocenoses. The results of studying the spatial structure of halophyte vegetation on the coasts of Iceland and Canada were obtained (Thannheizer 1991; Thannheizer, Hellfritz 1989).\u003c/p\u003e \u003cp\u003eThere is still no information about strict regularities in the distribution of seaside phytocenoses in the White Sea habitats. Until recently, there was practically no information about the vegetation of the White Sea southeastern coast and the coastal vegetation of the Kanin Peninsula middle part. Until now, there is no information on strict regularities in the coastal phytocenoses distribution in the White Sea habitats.\u003c/p\u003e \u003cp\u003eExisting studies have failed to address the distribution patterns shown by the phytocenoses inhabiting the coasts of the White and Barents Seas.\u003c/p\u003e \u003cp\u003eBy the example of the Barents Sea Pechora Bay, the first models of multivariate analysis of halophyte vegetation phytocenoses in different coastal biotopes were obtained (Moseev et al. \u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e2021\u003c/span\u003e; Moseev et al. \u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e2022\u003c/span\u003e). The distribution of plant associations in the White Sea littoral was built according to the salinity and pH factors influence (Moseev et al. \u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e2022\u003c/span\u003e). The purpose of this work is to present information about the distribution of halophytic vegetation phytocenoses in the White Sea coast and Cheshskaya Bay\u0026rsquo; coast of the Barents Sea biotopes and the impact of abiotic factors on the species composition of coastal phytocenoses.\u003c/p\u003e"},{"header":"Materials and methods","content":"\u003cp\u003eThe analysis of the coastal vegetation was carried out on the basis of 357 geobotanical descriptions made from the White Sea western coast to the Barents Sea Cheshskaya Bay. It includes the following small rivers mouths and lagoons localities: the Keret River mouth in the Kandalaksha Bay, the Kyanda and the Tapshenga rivers mouths of the Onega Bay and the Sukhoe (Dry) Sea Bay of the south-east of the Dvina Bay, the Kuya river mouth of the Dvina Bay, the Chizha river mouth of the Mezen Bay, the Chesha river mouth of the Cheshskaya Bay of the Barents Sea. (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e, Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eThe main part of the work was carried out by geobotanical profiling method. Profiles were laid in the direction from sea to land. On each profile, geobotanical descriptions of vegetation were made on sample areas 3 \u0026times; 3 m\u003csup\u003e2\u003c/sup\u003e in size in the habitats with homogenous conditions. The species composition, the total projective vegetation cover (PC), the partial projective cover for each species, the height of the tiers, the soil texture, and the influence degree of the sea water from tides and surges were determined on the sample areas. The geobotanical profiling method is recognized to be effective by many geobotanists in the study of vegetation cover of various types (Aleksandrova 1969; Whittaker 1980; Sergienko 2008).\u003c/p\u003e \u003cp\u003eCoastal phytocenoses formed on marshes change from the coastline of the sea to the basic shore, which makes it possible to obtain ecological and dynamic series of vegetation. The ecological-dynamic series is understood as a continuous interconnected chain of phytocenoses in accordance with changing environmental factors (Whittaker 1980). The transition from one phytocenosis to another can be smooth (diffused) or abrupt, which is facilitated by direct-acting ecological regimes change (Aleksandrova 1969).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eHydrological Conditions in the White Sea Small Rivers Mouths\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"5\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eRiver mouth or lagoon\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eMean tidal range, m\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eTidal flat types\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eTidal flats length in the river mouths, km\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eSalinity at the sea boundary, \u0026permil;\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eKeret\u0026rsquo;\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e1,7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eNarrow salt marshes with silty and clay soils. Stony spits.\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e3,0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e23,0\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eTapshenga\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e2,0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003eExtensive brackish marshes\u003c/p\u003e \u003cp\u003ewith peaty and silty soils at the top of the estuary. Narrow strip of salt marshes at the estuary sea boundary.\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e3,5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e19,3\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eKyanda\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e2,5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e8,0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e25,0\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eKuya\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e0,8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eNarrow brackish marshes with sandy-muddy substrate\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e3,0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e9,0\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eChizha\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e6,0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eExtensive salt marshes with silty and mud soils at the estuaries\u0026rsquo; sea boundary. Brackish marshes in estuary heads.\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e20,0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e26,0\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eChesha\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e3,5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eExtensive salt marshes with silty and clay soils at the estuaries\u0026rsquo; sea boundary. Brackish marshes in estuary heads.\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e8,0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e32,0\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSukhoe (Dry) Sea\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e1,0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eIn the deltas of the Kad and Mudyuga rivers there are extensive brackish marshes with peaty soils. Salt marshes with silty-sandy soils in the northern part.\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e3,0*\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e5,7**\u003c/p\u003e \u003cp\u003e9,2***\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003e \u003cdiv class=\"BlockQuote\"\u003e \u003cp\u003e* Length for the mouths of the Kad and Mudyuga rivers.\u003c/p\u003e \u003cp\u003e** Salinity for the Cad river mouth.\u003c/p\u003e \u003c/div\u003e \u003c/p\u003e \u003cp\u003e*** Salinity for the Bolshaya Nitsa river mouth in the northern part of the lagoon.\u003c/p\u003e \u003cp\u003eThe tidal range varies in the estuaries under study. V.N. Mikhaylov classifies tidal estuaries into microtidal with syzygial tide under 1.6 m, mezotidal with tide range between 1.6 m and 2.8, and macrotidal with tide range of more than 2.8 m (Mikhaylov, 1997).\u003c/p\u003e \u003cp\u003eOn the marshes, according to the shape of the coastal relief and depending on the tidal influence, several biotopes with specific vegetation cover and habitat conditions are distinguished (Leskov \u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e1936\u003c/span\u003e; Babina \u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e2002\u003c/span\u003e; Moseev et al., \u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e2021\u003c/span\u003e): 1 \u0026ndash; low-level marshes, twice a day covered by tidal waters, correspond to the lower boundary of the littoral upper horizon; 2 \u0026ndash; marshes of the flooding middle level by syzygial tidal waters, correspond to the boundary of the littoral upper horizon and are located 20\u0026ndash;50 cm above the low level; 3 \u0026ndash; high-level marshes, located above the boundary of syzygial tides, flooded by storm surge waters, in the oceanological classification they belong to the supralittoral zone.\u003c/p\u003e \u003cp\u003eThe non-metric multidimensional scaling method was used for the ordination of geobotanical descriptions. The Hellinger distance statistical measure was used for clustering phytocoenoses in different biotopes. This method is well suited for assessing the structure of phytocoenoses where coverage can range from 1 to 80%. The method helps to avoid zero values, which is important for clustering monodominant coastal communities (Legendr, Gallagher, 2001). Manhattan distance coefficients were used to analyze the similarity of species composition in plant communities. Calculations were performed using the R language (R Core Team, \u003cspan citationid=\"CR38\" class=\"CitationRef\"\u003e2019\u003c/span\u003e). The data were visualized with the ggplot2 package (Wickham, \u003cspan citationid=\"CR51\" class=\"CitationRef\"\u003e2016\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eGeobotanical descriptions were matched to hydrological indicators of salinity and tide levels, measured at the hydrological stations in estuaries and lagoons. Semi-diurnal observations of the tides range were carried out using a measuring rod tied to the defined zero of the post. For salinity measurements, a portable IDS Meter (HACH) conductometer and a Multi 3420 (WTW) multiparameter multimeter were used. Water pH measurements were made with pH meters from Hanna and Multi 3420 from WTW.\u003c/p\u003e \u003cp\u003eTo describe the growing conditions of halophyte plants in coastal vegetation communities, the SpH Index was derived. It determines the dependence of species on salinity and the aquatic environment pH. The SpH index was calculated by using the formula:\u003cdiv id=\"Equa\" class=\"Equation\"\u003e\u003cdiv format=\"TEX\" class=\"mathdisplay\" id=\"FileID_Equa\" name=\"EquationSource\"\u003e\n$$\\:SpH=\\frac{{S}_{0}}{S}\\times\\:\\frac{pH-{pH}_{ср}}{{pH}_{ср}}\\times\\:100$$\u003c/div\u003e\u003c/div\u003e,\u003c/p\u003e \u003cp\u003ewhere \u003cem\u003eS\u003c/em\u003e\u003csub\u003e\u003cem\u003e0\u003c/em\u003e\u003c/sub\u003e \u0026ndash; average salinity of the world\u0026rsquo;s ocean (34 psu), \u003cem\u003eS\u003c/em\u003e \u0026ndash; maximum observed salinity in community habitats in the high water of the tidal cycle, \u003cem\u003epH\u003c/em\u003e \u0026ndash; рН of the community habitat water, \u003cem\u003epH\u003c/em\u003e\u003csub\u003e\u003cem\u003eср\u003c/em\u003e\u003c/sub\u003e \u0026ndash; average рН water value in the habitats of all the communities under study.\u003c/p\u003e"},{"header":"Results","content":"\u003cp\u003e\u003cstrong\u003eCoastal biotopes vegetation of the White and Barents Seas\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eCoastal vegetation is heterogeneous in terms of biotope diversity, as it forms in ecotonal areas where the marine aquatic environment combines with land. The heterogeneity of coastal biotopes and their phytocoenoses can be assessed using a non-metric multidimensional scaling method. The graphic interpretation clearly reflects the various types of coastal biotopes, indicating differences in the influence of factors related to the impact of the sea and estuaries. The Figure 2 highlights areas with species lists of salt marshes, hydrophytic brackish marshes, cereal-sitnic brackish marshes, beaches, freshwater tidal drying areas at the tops of estuaries, shoals of the lower littoral and shallows of the upper sublittoral, and salt lakes, as well as saline lakes. Each of these habitat types differs in species composition and structure, as well as in the specific mechanical composition of the soils. Among the many factors that influence estuarine phytocoenoses, the main ones are: tides, storm surges, spring floods, salinity, pH, and substrate type.\u003c/p\u003e\n\u003cp\u003eTides are a crucial factor in the formation of coastal phytocenoses in the estuaries of the White and Barents Seas. Macrotidal estuaries are characterized by a significant diversity of phytocenoses, which distinguishes them from mesotidal and microtidal estuaries (Fig. 3a). Saline marshes and grass-sedge brackish marshes occupy the largest areas in macrotidal estuaries (Fig. 3b). Mesotidal estuaries are closely linked to macrotidal estuaries (Fig. 3a): extensive saline marshes form on the mouth marine bars, while expansive hydrophytic brackish marshes develop in the estuaries (Fig. 3b). Microtidal estuaries differ from macrotidal estuaries in that they have poorly expressed saline marshes. However, extensive areas of microtidal estuaries are occupied by hydrophytic brackish marshes, bringing them closer to mesotidal estuaries. Beaches are formed under the influence of surf at the marine boundary of any estuary. Narrow tidal flats develop at the heads of all estuaries. For mesotidal and microtidal estuaries, shoals of the lower littoral and shallow waters of the upper sublittoral have been identified.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eSalt marshes\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eSalt marshes are the most widely represented ecotopes type in river mouths and lagoons on the White and Barents Seas coasts. As can be seen from Figure 2, they are different from other types of biotopes. They develop at the sea boundary of estuaries and in lagoons at water salinity from 15 to 30\u0026permil; and are covered with phytocenoses dominated by obligate halophytes. The biotope is formed by the influence of saline tidal waters and storm surges.\u003c/p\u003e\n\u003cp\u003eTwenty-one associations were described in the composition of the salt marshes vegetation. The marshes tidal flats, flooded by the tide twice a day, are covered with associations communities such as \u003cem\u003eSalicornietum\u003c/em\u003e \u003cem\u003epojarkovae, Salicornietum\u003c/em\u003e \u003cem\u003epojarkovae tripoliosum vulgarae, Caricetum subspathaceae triglochinosum maritimae, Caricetum subspathaceae potentillosum egedae, Caricetum subspathaceae subpurum, Bolboschoenetum maritimi, Bolboschoenetum maritimi juncosum gerardii, Eleocharitetum uniglumis triglochinosum maritimi, Glaucetum maritimae, Puccinellietum phryganodis, Tripolietum vulgarae puccinelliosum phryganodis, Triglochinetum maritimi, Triglochinetum maritimi\u0026nbsp;\u003c/em\u003esubass.\u003cem\u003e\u0026nbsp;salicorniosum pojarkovae, Triglochinetum maritimi tripoliosum vulgarae.\u0026nbsp;\u003c/em\u003eThe\u003cem\u003e\u0026nbsp;\u003c/em\u003emid-level\u003cem\u003e\u0026nbsp;\u003c/em\u003esalt marshes tidal flats are covered by associations communities such as \u003cem\u003eCaricetum glareosae potentillosum egedae, Potentillosum egedae festucosum rubrae, Plantaginetum maritimae, Plantaginetum subpolarae, Sonchusetum humilis atriplexosum nudicaulis\u0026nbsp;\u003c/em\u003e(App. Table 1).\u003c/p\u003e\n\u003cp\u003eSalt marshes are better expressed in estuaries with macrotidal conditions. In the Chizha River estuary on the Mezen Bay coast, a broad phytocenoses diversity of salt marshes causes the vegetation high variegation.\u003c/p\u003e\n\u003cp\u003eThe marshes invasion begins with the obligate halophytes communities of \u003cem\u003ePuccinellietum phryganodis\u003c/em\u003e association (PC (\u003cem\u003etotal projective cover\u003c/em\u003e) \u0026ndash; 40\u0026ndash;60%), occupying the marshes silty tidal flats at the estuary sea boundary. They are daily exposed to the tide at salinity of about 26\u0026permil;, as they are under water for over three hours. The marshes tidal flats along the estuary coastline are covered with vegetation, flooded with tidal waters with salinity of 21\u0026ndash;25 \u0026permil;. The thickets of \u003cem\u003eSalicornia pojarkovae\u003c/em\u003e community (PC \u0026ndash; 30\u0026ndash;60%) are formed in micro-depressions. Closer to the basic shores silt-loam tidal flats are covered with vast communities of \u003cem\u003eCari\u003c/em\u003e\u003cem\u003eс\u003c/em\u003e\u003cem\u003eetum subspathaceae\u0026nbsp;\u003c/em\u003eassociation (PC \u0026ndash; 70\u0026ndash;90%), developing with daily tidal floods, the obligate halophyte \u003cem\u003eStellaria humifusa\u003c/em\u003e is found here in abundance as well. The phytocenoses of \u003cem\u003eCari\u003c/em\u003e\u003cem\u003eс\u003c/em\u003e\u003cem\u003eetum subspathaceae potentillosum egedae\u0026nbsp;\u003c/em\u003eassociation (PC \u0026ndash; 70\u0026ndash;95%) occupy tidal flats vast areas along the basic shores in the strip of syzygy tides. \u003cem\u003ePlantaginetum subpolaris\u0026nbsp;\u003c/em\u003eassociation communities (PC \u0026ndash; 50\u0026ndash;70%) are formed on the tidal troughs\u0026rsquo; silty shores of mid-level marshes.\u003c/p\u003e\n\u003cp\u003eIn mesotidal estuaries the areas occupied by marshes decrease. In the mouths of the Kyanda and Tapshenga rivers on the Onega Bay southeastern coast, the invasion of silty foreshores begins with the settlement of pioneering monodominant \u003cem\u003ePuccinellietum phryganodis\u0026nbsp;\u003c/em\u003eassociation communities, area 2\u0026ndash;4 m\u003csup\u003e2\u003c/sup\u003e, daily covered by the tide for about four hours at water salinity up to 25\u0026permil;. \u003cem\u003eTriglochinetum maritimi tripoliosum vulgarae\u0026nbsp;\u003c/em\u003e(PC \u0026ndash; 15\u0026ndash;50%) association, formed by succulent obligate halophytes, succeeds \u003cem\u003ePuccinellia\u003c/em\u003e communities on the silty-loamy foreshores of the lower layer marshes. They cover the foreshores areas up to 10 m\u003csup\u003e2\u003c/sup\u003e and are flooded by the tide over two hours daily at the water salinity about 23\u0026permil;. From the right bank of the Kyanda river estuary the same ecotopes are occupied by \u003cem\u003ePlantaginetum maritimae\u0026nbsp;\u003c/em\u003e(PC \u0026ndash; 20\u0026ndash;30%) association communities; in the Tapshenga river estuary there are monodominant \u003cem\u003eEleocharitetum uniglumis\u0026nbsp;\u003c/em\u003e(PC up to 80 %) communities. The listed above halophytic communities form a kind of microbelts of saline marshes coastal pioneer vegetation.\u003c/p\u003e\n\u003cp\u003eIn the direction to the basic shore the change of succulent halophyte vegetation is observed: \u003cem\u003eBolboschoenetum maritimi\u0026nbsp;\u003c/em\u003e(PC \u0026ndash; 50\u0026ndash;90%) association phytocenoses form the second marshes overgrowth belt on the Onega Bay coast. They occupy large areas of the silty-loamy marshes foreshores in the tops of the Nimenga and Kyanda bays; their narrow bands penetrate 2-4 km up the estuaries with the daily tidal waters flooding at 15\u0026ndash;25\u0026permil;.\u003c/p\u003e\n\u003cp\u003eThe primary vegetation background of the mesotidal Keret river estuary (and Keret Bay) is formed by \u003cem\u003eTriglochinetum maritimi\u0026nbsp;\u003c/em\u003e(PC \u0026ndash; 20\u0026ndash;40%) and \u003cem\u003eEleocharitetum uniglumis triglochinosum maritimi\u0026nbsp;\u003c/em\u003e(PC \u0026ndash; 30\u0026ndash;60%) associations communities, developing on the silty-loamy foreshores flooded by the tidal waters at 5\u0026ndash;20\u0026permil; salinity. In the syzygial tides influence zone these communities are succeeded by \u003cem\u003eCaricetum subspathaceae\u0026nbsp;\u003c/em\u003eassociation,\u003cem\u003e\u0026nbsp;\u003c/em\u003ewhich occupies small areas on the marshes\u0026rsquo; loamy foreshore. There \u003cem\u003ePhragmitetum australis\u003c/em\u003e association communities can be also found, as those small areas are flooded by brackish waters (about 25\u0026permil; salinity). At the estuary head they give place to \u003cem\u003eHippuridetum tetraphyllae\u0026nbsp;\u003c/em\u003eassociation at 5\u0026ndash;10\u0026permil; water salinity.\u003c/p\u003e\n\u003cp\u003eIn the microtidal estuaries of the Dvina Bay southeastern part, including a shallow lagoon - the Sukhoe Sea Bay, salt marshes occupy even smaller areas due to the desalination of the waters of the large Northern Dvina river and small rivers the Kuya, the Mudyuga, the Kad, and the Bolshaya Nitsa.\u003c/p\u003e\n\u003cp\u003eOn the west coast monodominant \u003cem\u003ePuccinellietum phryganodis\u003c/em\u003e association communities occur on the Sukhoe Sea sandy foreshores, daily covered by tidal sea waters. At the Bolshaya Nitsa river mouth and near the bay west shore \u003cem\u003eBolboschoenetum maritimi\u0026nbsp;\u003c/em\u003e(PC \u0026ndash; 30\u0026ndash;70%) association halophyte communities develop on the silty foreshores, daily flooded by tidal waters at up to 10\u0026permil; salinity. On the Nikolskaya spit, where the salinity of the Sukhoe Sea bay surrounding waters reaches 15 \u0026permil;, \u003cem\u003eSalicornietum europeaea, Triglochinetum maritimi\u003c/em\u003e associations communities develop.\u003c/p\u003e\n\u003cp\u003eIn some respects, the saltmarsh biotope is similar to grass-rush biotope of brackish marshes, which is due to the presence in its composition of relative halophytes, i.e. species resistant to mild to medium salinity of substrate. These include \u003cem\u003eAlopecurus arundinaceus\u003c/em\u003e and \u003cem\u003eJuncus gerardii\u003c/em\u003e.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eBrackish marshes\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eBrackish marshes occupy large areas in the tops of river estuaries and on the shores of lagoons washed by waters with a salinity of 1 to 15 \u0026permil;. The vast biotope found in the White Sea, in turn, clearly shows occurrence of two structurally independent ecotopes: hydrophytic brackish marshes and cereal-sitnik brackish marshes. The bottom of low-lying marshes is formed by silt, sand and silty sand, that of middle marshes by peat deposits, and that of high marshes by loamy soils with thin sod layer.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e\u003cem\u003eHydrophytic brackish marshes\u003c/em\u003e\u0026nbsp;\u003c/strong\u003eare formed in the mesotidal estuaries of the Onega (Kyanda and Tapshenga) and microtidal estuaries of the Dvinsky Bay (estuaries of the rivers of the Dry Sea Bay - Bolshaya Nitsa, Kad, Mudyuga). In Figure 2 they are formed into a separate \u0026ldquo;cloud\u0026rdquo; from other phytocenoses, which indicates significant geomorphological and geobotanical differences of these communities from phytocenoses of other biotopes. These phytocenoses are formed under the influence of brackish tidal waters and are to a lesser extent affected by storm surges. However, observations indicate that spring floods play a significant role in their development. Freshwater floodwaters stagnate in the marsh, which promotes the germination of hydrophilic species that form phytocenoses.\u003c/p\u003e\n\u003cp\u003eIn the zone of the diurnal tide, the communities of hygrophytic marshes are formed by thickets of \u003cem\u003ePhragmites australis\u003c/em\u003e. Along the gradient to the land in the syzygial tides and surges influence zone, in addition to \u003cem\u003ePhragmites australis\u003c/em\u003e, facultative halophytes \u003cem\u003eAlopecurus arundinaceus\u003c/em\u003e and \u003cem\u003eJuncus gerardii\u003c/em\u003e, take part in their formation, as well as obligate halophytes \u003cem\u003eTriglochin maritima, Stellaria humifusa\u003c/em\u003e, and \u003cem\u003eCarex salina\u003c/em\u003e at the mouth of the Bolshaya Nitsa river\u003cem\u003e. Eleocharis acicularis\u003c/em\u003e co-dominates in depressions, along the banks of small channels, on muddy tidal flats. Reedbeds play an important environment-forming role in the Sukhoe Sea bay, contributing to eutrophication, the coastline silting, and reducing the wave-built impact on the coast. Moving into the bay, they contribute to the leveling of the coastline, displacing halophytic communities at that. Rotting, reed waste forms a peat subsoil, the thickness of which increases on the marshes of the upper and middle levels of tidal flooding, where soil silting decreases. This type of vegetation forms reed shores, also known in the Baltic, Black and Azov seas (Rebassoo 1975; Ivanov et al. 2008; Moseev 2014). At the sea boundaries of the mouths of the Kuya, Mudyuga, Kad, and Bolshaya Nitsa rivers, communities of the \u003cem\u003ePhragmitetum australis bolboschoenosum maritimi\u003c/em\u003e association (PC \u0026ndash; 60\u0026ndash;100%) develop, occupying silty tidal flats marshes, daily flooded by the tide at a water salinity of up to 5.2\u0026ndash;10.0 \u0026permil; (App. Table 3).\u003c/p\u003e\n\u003cp\u003eOn the upstream silty flats, they are superseded by reed thickets of the subassociation \u003cem\u003ePhragmitetum australis subpurum\u003c/em\u003e (GPC 90-100%), forming an extensive belt along the estuarine shoreline and distributing from the low-lying flats to the high marshes. Here, the reedbeds play an important environmental role as contributors to eutrophication and accretion of silt along the shore, as well as mitigators of swash action.\u003c/p\u003e\n\u003cp\u003eThe vegetation cover of the \u003cem\u003emesotidal\u0026nbsp;\u003c/em\u003eestuaries of the Kyanda and Tapshenga rivers in the southeast of the Onega Bay is similar to that one in the southeast of the Dvina Bay. Here, silty tidal flats of low-level brackish marshes are covered with communities of the \u003cem\u003ePhragmitetum australis bolboschoenosum maritimi\u003c/em\u003e association occupying the same ecotopes. Upstream of the rivers, on low-level marshes silty tidal flats, they are succeeded by dense reedbeds of the \u003cem\u003ePhragmitetum australis subpurum subassociation\u003c/em\u003e (PC \u0026ndash; 90\u0026ndash;100%), forming an extensive belt along the estuarine shoreline and spreading from low level drainages down to high level marshes. Reed thickets play an important habitat-forming role in the bay, contributing to eutrophication, siltation of the shoreline, and reduction of wave action on the shore. Such communities can develop both in brackish (1\u0026ndash;20\u0026permil;) and fresh waters of marshes up to ecotopic zones with transitional communities. Reeds also settles up the rivers to estuaries tops at the forests boundary, where there are prominent signs of swamp-formation with inclusions of sphagnum mosses. Reeds thickets, playing an environment-forming role on the marshes, as well as in the Sukhoe Sea, form the main vegetation aspect of the Onega Bay southern coast. Marshes occupied by reeds, in the Sukhoe Sea occupy a coastal zone more than 3 km wide up the rivers\u0026rsquo; mouths and form a specific type of phytogenic shores called reed banks (Leontiev et al. 1975).\u003c/p\u003e\n\u003cp\u003eThe brackish marshes of the tidal zone are inhabited by monodominant phytocenoses of \u003cem\u003eBolboschoenus maritimus\u003c/em\u003e, which form here on low-lying flats the narrow strips exposed to a diurnal tide cycle. In Figure 2, they appear as a stand-alone \u0026ldquo;cloud\u0026rdquo; at the top and mainly depend on tidal processes. Exposure to the diurnal tidal cycle stimulates the growth of \u003cem\u003eBolboschoenus maritimus\u003c/em\u003e across extensive range with water salinity between 10\u0026permil; and 25\u0026permil;. Contributing to the accumulation of suspended and entrained sediments, the thickets of \u003cem\u003eBolboschoenus maritimus\u003c/em\u003e cause major silting. In the Bolshaya Nitsa estuary and near the western shore of the bay, the halophytic communities of the association \u003cem\u003eBolboschoenetum maritimi\u003c/em\u003e (PC 30-70%) occur on silty flats exposed to tidal influxes of 10\u0026permil; salinity.\u003c/p\u003e\n\u003cp\u003eThe macrotidal estuaries of the Chizha and Chesha are home to brackish \u003cstrong\u003e\u003cem\u003eCereal-sitnik marshes (Seaside meadows)\u003c/em\u003e\u003c/strong\u003e. In Figure 2, they appear as a stand-alone \u0026ldquo;cluster\u0026rdquo; lying next to that of salt marshes. Such habitats are formed under the influence of storm surge waters. Their communities occupy areas near the waterline (intermediate marshes) and are influenced by tides.\u003c/p\u003e\n\u003cp\u003eOn the low marshes silty soils, facultative halophytes communities develop, of which the communities of the \u003cem\u003eAlopecuretum arundinacei\u003c/em\u003e association (PC, 45\u0026ndash;99%) are of great importance in the secondary marshes invasion; they form strips along the estuary bank line and on the loamy terraces tidal flats daily flooded by the tide.\u003c/p\u003e\n\u003cp\u003eOn loamy soils along tidal troughs, narrow strips form hygrophytic communities of the \u003cem\u003eAlopecuretum arundinacei caricosum salinae\u003c/em\u003e association (PC, 35\u0026ndash;80%). The dominant species \u003cem\u003eCarex salina\u003c/em\u003e forms an overgrowth microbelt along tidal troughs on loamy substrates that are daily flooded, and higher is succeeded by \u003cem\u003eAlopecurus arundinaceus\u0026nbsp;\u003c/em\u003emicrobelt. Small micro-depressions, flooded by syzygial tides, are occupied by the \u003cem\u003eJuncosum gerardii\u003c/em\u003e association (App. Table 3).\u003c/p\u003e\n\u003cp\u003eHygrophilous communities give place to oligo- and poly-dominant communities of high-level coastal meadows from the \u003cem\u003eFestucetum rubrae alopecurosum arundinacei (\u003c/em\u003ePC \u0026ndash; 80\u0026ndash;100%) and \u003cem\u003eFestucetum rubrae juncosum gerardii\u0026nbsp;\u003c/em\u003e(PC \u0026ndash; 80\u0026ndash;100%) associations, which develop on loamy soils and occupy an area of tens of and even hundreds of square meters.\u003c/p\u003e\n\u003cp\u003eAt the mouth of the Kyanda River on old coastal ridges with sandy loamy soils in the surges influence zone, an association of \u003cem\u003eElytrigietum repentis\u003c/em\u003e was identified, where, besides \u003cem\u003eElytrigia repens, Sonchus humilis co-dominates\u003c/em\u003e in the lower layer.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eTidal flats in the estuaries\u0026rsquo; tops\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eStructurally similar to brackish marshes are the tidal flats in the estuarine headwater region. Like hygrophytic brackish marshes, they experience 2 tides a day but are reached by saline tidal waters only rarely and highly infrequently. For this reason, here occur freshwater phytocenoses, which appear in this coastal vegetation ecological series as a closing element stretching from the estuaries\u0026rsquo; marine boundary towards headwater region. Such communities form a \u0026quot;cluster\u0026quot; near hydrophytic brackish marshes, indicating similar living conditions. This fact is shown in the graphical interpretation of the ordination in Figure 2. However, these phytocenoses are formed under the influence of freshwater and are only occasionally affected by the brackish waters of storm surges.\u003c/p\u003e\n\u003cp\u003eIn the southeast of the Dvina Bay, the communities of sub-associations \u003cem\u003ePhragmitetum australis scirposum lacustris\u003c/em\u003e (PC, 30\u0026ndash;50%) and \u003cem\u003ePhragmitetum australis petasitosum radistis\u003c/em\u003e occupy the narrow freshwater estuary tops. In the tops of all the rivers estuaries on the White Sea and Cheshskaya Bay coast, large sedge communities of the \u003cem\u003eCaricetum aquatilis\u003c/em\u003e association are present, forming thickets on low-level silty tidal flats, common for fresh water bodies and streams, and in the southeast of the Dvina Bay, also communities of the \u003cem\u003eCaricetum acutae\u003c/em\u003e association occur (App. Table 3).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eSalt lakes\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eIn Figure 2, this biotope represents a small \u0026ldquo;cluster\u0026rdquo; lying next to the sublittoral and saltmarsh biotopes, since halophyte communities occur here as well.\u003c/p\u003e\n\u003cp\u003eThey are formed as a result of rivers\u0026rsquo; mouths channels change (loop-lakes) or in micro-depressions because of the soil reduction under the influence of tides and surges. Bottom sediments of salt lakes are silty soils. The water ponds (less than 100-200 m\u003csup\u003e2\u003c/sup\u003e in area) depth does not usually exceed 0.5 m. In the majority of the salt lakes marshes the most typical communities belong to \u003cem\u003eHippuridetum tetraphillae\u0026nbsp;\u003c/em\u003eassociation (Table 3), they occupy the small lakes and their coasts with silty soils to the 10-30sm depth and sometimes cover the lakes complete water areas. They can develop at a significant salinity range change (5-30\u0026permil;). Studies show that these communities do not depend much on the tides influence, since they do not dry out in low water. But since they have a narrow range of habitats, they are stenotopic. Ассоциация \u003cem\u003eHippuridetum tetraphillae\u003c/em\u003e association is present in the salt lakes along the entire White Sea coast. Hydrophyte communities of other associations, such as \u003cem\u003eMyriophilletum sibirici, Potametum pectinati\u003c/em\u003e, can also develop in the marshes\u0026rsquo; brackish lakes (App. Table 3).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eShoals of the lower littoral\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eConcentrating on the middle and lower levels of the littoral, the watte flats differ from marshes by their poorly developed vascular plant cover. In Figure 2, this biotope represents a small \u0026ldquo;cluster\u0026rdquo; lying next to the sublittoral and saltmarsh biotopes, since halophyte communities occur here as well. The lower littoral dries up completely only during syzygial ebbs. Here in silt-covered tide pools, occur hydrophytic communities of the associations \u003cem\u003eRuppietum maritimae\u003c/em\u003e and \u003cem\u003eZosteretum marinae\u003c/em\u003e (App. Table 3). They exist here in conditions of widely fluctuating water salinity of 10\u0026permil; to 30\u0026permil;, but do not dry up completely during moderately high tides and are less susceptible to water level fluctuations during the tidal cycle compared to saltmarsh communities.\u003c/p\u003e\n\u003cp\u003eThe biotope of the lower littoral zone is represented by vast silty tidal flats (waddens), which are almost devoid of macrophyte vegetation. The lower littoral dries up completely only at syzygial tides. In littoral baths on silty tidal flats the hydrophyte communities of \u003cem\u003eRuppietum maritimae\u0026nbsp;\u003c/em\u003eand \u003cem\u003eZosteretum marinae\u003c/em\u003e are formed (Table 3) in the conditions of the significant changes of the water salinity (10-30\u0026permil;) and tides level fluctuations. We gave the description of such communities in the Keret river estuary and in the Sukhoe Sea bay in the south-east Dvina bay. In the direction to the land, the waddens are replaced by marshes \u0026ndash; coastal areas, covered with halophytic vegetation, and which are the result of their genesis (Kaplin et al., 1991).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eShallows of the upper sublittoral\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe bottom substrates of the upper sublittoral are mainly covered with macrophyte algae communities. Of the macrophyte plants in the White Sea, this biotope is characterized only by \u003cem\u003eZosteretum marinae\u003c/em\u003e association communities (App. Table 3), which form \u0026ldquo;underwater meadows,\u0026rdquo; as well as other sea weeds communities.\u003c/p\u003e\n\u003cp\u003eCommunities of the \u003cem\u003eZosteretum marinae\u003c/em\u003e association with the participation of brown algae \u003cem\u003eFucus vesiculosus\u003c/em\u003e occupy depths of 1-1.5 m in low water on silty bottoms along the entire coast of the estuary of the Keret river (Keret Bay). They are formed with significant changes in water salinity from 23 \u0026permil; at the sea boundary of the estuary to 10 \u0026permil; at its head at the maximum tide level. The seagrass \u003cem\u003eZostera marina\u003c/em\u003e develops here under the halocline influence, due to which it inhabits the estuary areas with colder and saltier waters compared to the foreshores.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eBeaches\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe beaches of the White Sea coast stretch out for long distances. The phytocenoses of this biotope differ significantly in species composition and the impact of abiotic factors from the marshes phytocenoses (Fig. 2 (section 8)). Beaches are formed under the influence of waves and wind. This factor of influence distinguishes them from swamps. Tides and surges play a negligible role in their formation.\u003c/p\u003e\n\u003cp\u003eThe vegetation of the beaches on the White and Barents Seas coasts is rather monotonous. It contains 4 associations: \u003cem\u003eLeymetum arenarii honckenyosum diffusae,\u0026nbsp;\u003c/em\u003e\u003cem\u003eLeymetum arenarii latirosum japonici,\u0026nbsp;\u003c/em\u003e\u003cem\u003eLeymetum arenarii plantaginosum maritimae\u0026nbsp;\u003c/em\u003e(App. Table 4)\u003cem\u003e.\u0026nbsp;\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003eThe closest to the coastal line are the communities of \u003cem\u003eLeymetum arenarii honckenyosum peploidis\u0026nbsp;\u003c/em\u003eassociation, they occupy the coastal ridges and their slopes facing the sea. In the White Sea on the sandy coastal ridges very close to the Sukhoe (Dry) Sea Bay coastal line \u003cem\u003eLeymetum arenarii plantaginosum maritimae\u0026nbsp;\u003c/em\u003ecommunities were found. Coming close to the basic shores one can observe that \u003cem\u003eLeymetum arenarii honckenyosum peploidis\u003c/em\u003e association communities give place to \u003cem\u003eLeymetum arenarii lathyrosum japonici\u0026nbsp;\u003c/em\u003eassociation\u003cem\u003e,\u0026nbsp;\u003c/em\u003ewhich communities cover distant from the coastline sandy coastal ridges and dunes. The vegetation owes its homogeneity to the communities being dominated mostly by 3 psammophytic species: \u003cem\u003eLeymus arenarius, Honckenya peploides, Lathyrus aleuticus\u003c/em\u003e. Some of these communities often include nitrophiles, which dominate due to the local accumulations of seaweed: \u003cem\u003eAtriplex nudicaulis, Atriplex litoralis, Atriplex praecox, Plantago maritima, Glaux maritimus\u003c/em\u003e. Occurring also on marshes, and as can be seen from their location in Figure 2, these species make the biotopes under study similar in terms of composition of their communities.\u003c/p\u003e\n\u003cp\u003eSalinity and pH of the water are important factors influencing the coastal plants growth in the biotopes of the littoral zone.\u003c/p\u003e\n\u003cp\u003eIndexing of both factors shows that facultative halophytes can live with significant variability in salinity and pH, forming communities on brackish marshes, but also growing in salt marshes biotopes (Fig. 5). These are 25 species of vascular plants: \u003cem\u003eTriglochin palustris, Agrostis stolonifera, Alopecurus arundinaceus, Leymus arenarius, Puccinellia distans, Carex recta, Carex saxatilis, Eleocharis uniglumis, Schoenoplectus tabernaemontani, Juncus arcticus, Juncus gerardii, Ranunculus hyperboreus, Cochlearia arctica, Parnassia palustris, Lathyrus aleuticus, Hippuris\u0026nbsp;\u003c/em\u003e\u003cem\u003e\u0026acute;\u003c/em\u003e\u003cem\u003e\u0026nbsp;lanceolata Angelica litoralis, Ligusticum scoticum, Cenolophium denudatum, Armeria scabra, Polemonium boreale, Crepis nigrescens, Lactuca tatarica, Tephroseris palustris, Sonchus humilis, Tripleurospermum maritimum.\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003eObligate halophytes (euglophytes), tending to biotopes of salt marshes, upper sub-littoral and lower littoral, salty lagoon lakes, are steno-bionts, as they grow in the conditions of small water salinity and pH fluctuations. These are 31 types: \u003cem\u003eZostera marina, Ruppia maritima, Triglochin maritima, Agrostis straminea, Calamagrostis deschampsioides, Dupontia psilosantha, Puccinellia coarctata, Puccinellia maritima, Puccinellia phryganodes, Puccinellia pulvinata, Puccinellia capillaris, Carex glareosa, Carex mackenziei, Carex maritima, Carex salina, Carex subspathacea, Bolboschoenus maritimus, Blysmus rufus, Atriplex nudicaulis, Salicornia pojarkovae, Stellaria humifusa, Honckenya peploides\u0026nbsp;\u003c/em\u003esubsp. \u003cem\u003ediffusa, Potentilla egedii, Hippuris tetraphylla, Primula finmarchica, Glaux maritima, Plantago maritima, Plantago subpolaris, Plantago schrenkii, Arctantemum hulteni, Tripolium pannonicum.\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003eIn the conditions of low pH variability, tolerant to salinity glycophytes live, prevailing on brackish marshes and in brackish lagoon lakes, there are 14 species: \u003cem\u003ePotamogeton pectinatus, Arctophila fulva, Calamagrostis neglecta, Elytrigia repens, Festuca rubra, Festuca arenaria, Festuca richardsonii, Phragmites australis, Eleocharis acicularis, Allium schoenoprasum, Rumex aquaticus, Callitriche hermaphroditica, Empetrum hermaphroditum, Myriophyllum sibiricum\u003c/em\u003e. However, as the research shows these plants are able to tolerate rather significant salinity fluctuations.\u003c/p\u003e"},{"header":"Discussion","content":"\u003cp\u003eThe similarities and differences between the coastal vegetation of the estuaries of the White Sea and the Cheshskaya Bay are well reflected in the graphical interpretation of their communities in Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e6\u003c/span\u003e.\u003c/p\u003e \u003cp\u003eThe coastal vegetation of the mesotidal and microtidal estuaries of the Dvina and Onega bays is the most similar (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e6\u003c/span\u003e). Here, the largest areas are occupied by brackish marshes with specific communities of \u003cem\u003ePhragmitetum australis\u003c/em\u003e associations, where mainly the freshwater plant species prevail, however, the hygrophile halophytes are also present. Such communities develop in a wide range water salinity change in river estuaries on marshes of a mid-level tide influence. The main aspect of the vegetation cover of the low-level marshes is created by \u003cem\u003eBolboshoenetum maritimi\u003c/em\u003e association communities. At that, the communities with prevailing succulent obligate halophytes from the associations \u003cem\u003eTriglochinetum maritimi, Glaucetum maritimae, Salicornietum pojarkovae, Plantaginetum maritimae\u003c/em\u003e mainly occupy small areas at the estuaries\u0026rsquo; sea boundaries. Hydrophyte \u003cem\u003eZostera marina\u003c/em\u003e forms communities in the aquatic environment of the lower sublittoral.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eThe vegetation of the Chizha river, which flows into the Mezensky Bay, and the Chesha river, which flows into the Cheshskaya Bay estuaries, differs significantly from the Dvina and Onega bays vegetation (Fig.\u0026nbsp;3). Here, on the sea boundary, the main areas of silty-loamy tidal flats of the low and mid-level marshes are occupied by salt marshes with characteristic communities of obligate halophytes from \u003cem\u003eCaricetum subspathaceae, Caricetum subspathaceae potentillosum egedii, Caricetum glareosae, Plantaginetum subpolaris, Puccinellietum phryganodis, Salicornietum pojarkovae, Triglochinetum maritimi\u003c/em\u003e associations. The brackish marshes biotopes are located at the river mouths heads. The low-level brackish marshes tidal flats are covered with the communities of \u003cem\u003eAlopecuretum arundinacei, Alopecuretum arundinacei caricosum salinae\u003c/em\u003e associations. High-level marshes tidal flats are covered by the communities \u003cem\u003eFesticetum rubrae juncosum gerardii, Festucetum rubrae alopecurosum arundinacei\u003c/em\u003e associations.\u003c/p\u003e \u003cp\u003eAt the Keret river mouth of the Kandalaksha Bay the hygrophilous communities of succulents \u003cem\u003eEleocharitetum uniglumis triglochinosum maritimi, and Triglochinetum maritimi\u003c/em\u003e prevail, which places the Keret river estuary vegetation close to the one of the Chesha river estuary. The aquatic environment of the lower littoral is characterized by communities of \u003cem\u003eRuppietum maritimae\u003c/em\u003e, and of the sublittoral by Zosteretum marinae, which makes the vegetation structure of the Keret river similar to the Dvina Bay southeastern coast.\u003c/p\u003e \u003cp\u003eGraphical interpretation of biotopes by oceanic zones shows a significant similarity between the coastal vegetation of the middle and upper littoral and supralittoral. These zones include biotopes formed under the influence of tidal waters and storm surges: mid- and low-level salt marshes, mid- and high-level brackish marshes, saline lagoon lakes and beaches. Their communities occupy the largest areas on the seas coasts.\u003c/p\u003e \u003cp\u003eThe vegetation of the arctic salt marshes of the Mezen and the Cheshskaya Bays is close in composition and structure to the vegetation of the coasts of Iceland, southern Greenland, and northern Norway (Nordhagen \u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e1954\u003c/span\u003e; Thannheiser \u003cspan citationid=\"CR45\" class=\"CitationRef\"\u003e1975\u003c/span\u003e; \u003cspan citationid=\"CR47\" class=\"CitationRef\"\u003e1991\u003c/span\u003e; Thannheiser, Willers T. \u003cspan citationid=\"CR49\" class=\"CitationRef\"\u003e1988\u003c/span\u003e; Thannheiser, Hellfritz \u003cspan citationid=\"CR50\" class=\"CitationRef\"\u003e1989\u003c/span\u003e). The similarity lies in the species composition of the associations \u003cem\u003eSalicornietum pojarkovae, Caricetum subspathaceae triglochinosum maritimae, Caricetum subspathaceae potentillosum egedii, Caricetum subspathaceae subpurum, Glaucetum maritimae\u003c/em\u003e, \u003cem\u003ePuccinellietum phryganodis, Tripolietum vulgarae puccinelliosum phryganodis, Triglochinetum maritimi, Triglochinetum maritimi salicorniosum pojarkovae, Triglochinetum maritimi tripoliosum vulgarae, Caricetum glareosae potentillosum egedii, Potentillosum egedii festucosum rubrae, and Plantaginetum subpolarae.\u003c/em\u003e Large areas occupied by the communities of \u003cem\u003eCaricetum subspathaceae subpurum\u003c/em\u003e, \u003cem\u003eCaricetum glareosae potentillosum egedii\u003c/em\u003e associations \u003cem\u003eindicate\u003c/em\u003e the similarity with Chukchi and Bering Seas coasts (Sergienko 2008), including the Korf bay (Neshataeva et al. \u003cspan citationid=\"CR34\" class=\"CitationRef\"\u003e2014\u003c/span\u003e). In general, the halophyte vegetation of the mouths of the Chizha and Chesha rivers on the Kanin Peninsula has many similar communities with the ones of the southeastern coast of the Barents Sea, described in the works (Matveeva and Lavrinenko \u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e2011\u003c/span\u003e; Lavrinenko and Lavrinenko \u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e2018\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eThe brackish marshes of the southeast Dvina and Onega bays, which, according to the classification of V. Chapman, belong to the boreal type (Chapman \u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e1960\u003c/span\u003e; \u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e1964\u003c/span\u003e), show similarities with the coast of the Baltic Sea (Rebassoo \u003cspan citationid=\"CR39\" class=\"CitationRef\"\u003e1975\u003c/span\u003e; Rebassoo \u003cspan citationid=\"CR37\" class=\"CitationRef\"\u003e1987\u003c/span\u003e). But at the same time, due to the dominance of large macrophytes \u003cem\u003ePhragmites australis, Bolboschoenus maritimus\u003c/em\u003e in the communities composition, their vegetation cover is similar even to the flood plains of the Azov Sea and the Black Sea estuaries (Golub \u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e2017\u003c/span\u003e; Grechushkina et al \u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e2011\u003c/span\u003e; Preislerov\u0026aacute; et al \u003cspan citationid=\"CR36\" class=\"CitationRef\"\u003e2022\u003c/span\u003e). The salt marshes communities at the sea boundary of the rivers\u0026rsquo; Sukhoe Sea Bay are similar to the communities of the sea coasts of Northern Norway (Nordhagen \u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e1954\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eIn its turn, the vegetation of the Keret river mouth in the Kandalaksha Bay is similar to other areas of the White Sea western coast (Babina \u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e2002\u003c/span\u003e; Vekhov and Georgievsky \u003cspan citationid=\"CR53\" class=\"CitationRef\"\u003e1984\u003c/span\u003e; Sergienko \u003cspan citationid=\"CR42\" class=\"CitationRef\"\u003e2013\u003c/span\u003e). In addition, the salt marshes of the White Sea both the eastern and southeastern coasts have many similar communities with the northern coast (Koroleva et al. 2011).\u003c/p\u003e \u003cp\u003e \u003cem\u003eEleocharitetum uniglumis\u003c/em\u003e association communities, widely spread in the Onega, Dvina and Kandalaksha bays, are also known on the coasts of the Baltic Sea (Siira \u003cspan citationid=\"CR43\" class=\"CitationRef\"\u003e1987\u003c/span\u003e) and the Norwegian Sea (Thannheiser \u003cspan citationid=\"CR47\" class=\"CitationRef\"\u003e1991\u003c/span\u003e).\u003c/p\u003e \u003cp\u003e \u003cem\u003eHippuridetum tetraphillae\u003c/em\u003e association of salt lakes is widespread along the White Sea entire coast (Babina \u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e2002\u003c/span\u003e; Koroleva et al. 2011; Moseev, Sergienko \u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e2020\u003c/span\u003e). Its communities are known in the southeast of the Barents Sea (Matveeva, Lavrinenko \u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e2011\u003c/span\u003e, Moseev, Sergienko, \u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e2020\u003c/span\u003e, Moseev et al., \u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e2022\u003c/span\u003e), on the shores of the Chukchi and Bering Seas (Neshataeva et al \u003cspan citationid=\"CR34\" class=\"CitationRef\"\u003e2014\u003c/span\u003e; Sergienko 2008), the seas of North America (Nordhagen \u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e1954\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eCommunities of the upper littoral and lower sublittoral from the \u003cem\u003eZosteretum marinae\u003c/em\u003e association develop along the White Sea entire western coast (Vekhov \u003cspan citationid=\"CR53\" class=\"CitationRef\"\u003e1984\u003c/span\u003e), locally along the northern (Bologna 1984) and western coasts of the seas of Europe (Wong et al. \u003cspan citationid=\"CR55\" class=\"CitationRef\"\u003e2021\u003c/span\u003e), the Black and Azov Seas (Kalugina Gutnik 1975; Milchakova \u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e1988\u003c/span\u003e; Sadogursky 1999), at the coasts of North America (Lopez-Calderon 2016), in the seas of the Far East (Kalita, Skriptsova \u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e2018\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eDue to the dominance of the large grass \u003cem\u003eLeymus arenarius\u003c/em\u003e and the creeping arctic-boreal species \u003cem\u003eHonckenya peploides\u003c/em\u003e, the vegetation of the beach psammophyton is similar to the vegetation of the beaches of the coasts of Iceland and northern Norway (Thannheiser \u003cspan citationid=\"CR46\" class=\"CitationRef\"\u003e1987\u003c/span\u003e; \u003cspan citationid=\"CR48\" class=\"CitationRef\"\u003e1998\u003c/span\u003e).\u003c/p\u003e"},{"header":"Conclusion","content":"\u003cp\u003eBy using the technique of metric multidimensional scaling, we have identified a total of seven types of biotopes occurring on the coast of the White Sea and the Chesha Bay, each with its own vegetation composition and structure \u0026ndash; saltmarsh, brackish marsh, beach, salt lagoon lakes, lower-littoral watte flat, upper-sublittoral silt sand soil. These biotopes differ in vegetation, location within oceanic zones, soil mechanics, and tide height. The brackish marsh type has been found to comprise 2 clearly distinct biotopes: hygrophytic brackish marshes and cereal-sitnic brackish marshes.\u003c/p\u003e \u003cp\u003eSalt marshes are the main biotope on the sea boundaries of the estuaries of the Mezen Bay and the Cheshskaya Bay, Kandalaksha Bay, where the water salinity reaches 15\u0026ndash;32\u0026permil;. The largest areas in the biotope are occupied by communities of \u003cem\u003eSalicornietum pojarkovae, Caricetum subspathaceae potentillosum egedii, Caricetum subspathaceae subpurum, Puccinellietum phryganodis, Triglochinetum maritimi, Triglochinetum maritimi tripoliosum vulgarae, Caricetum glareosae potentillosum egedii, Plantaginetum maritimae, Plantaginetum subpolarae\u003c/em\u003e associations.\u003c/p\u003e \u003cp\u003eHere brackish marshes distinctly classify into the following two biotopes: hygrophytic marshes and hygromesophytic (grass-rush) marshes. The hygrophytic brackish marshes occur within the Onega estuary and the southeastern sector of the Dvina Bay, where water salinity decreases to the range of 1\u0026ndash;20\u0026permil;. Vast areas within this biotope are occupied by the communities of the associations \u003cem\u003eBolboschoenetum maritime\u003c/em\u003e and \u003cem\u003ePhragmitetum australis\u003c/em\u003e. The other biotope \u0026ndash; hygromesophytic brackish marshes \u0026ndash; occurs within the estuaries of the Mezen Bay and Chesha Bay. Here, the ecological niche of the boreal species \u003cem\u003ePhragmites australis\u003c/em\u003e and \u003cem\u003eBolboschoenus maritimus\u003c/em\u003e is occupied by the Arctic boreal grass \u003cem\u003eAlopecurus arundinaceus\u003c/em\u003e, which forms communities of the association \u003cem\u003eAlopecuretum arundinacei\u003c/em\u003e on vast areas within headwater regions of the Chizha estuary and the Chesha estuary, whereas the vegetation of high marshes is formed by the of communities of \u003cem\u003eJuncus gerardii\u003c/em\u003e and \u003cem\u003eFestuca rubra\u003c/em\u003e, some including \u003cem\u003eAlopecurus arundinaceus\u003c/em\u003e.\u003c/p\u003e \u003cp\u003eIn the estuaries of the Onega Bay and the Dvina Bay southeast, brackish marshes are formed due to a decrease in water salinity to 1\u0026ndash;15\u0026permil;. The largest areas in the biotopes are occupied by communities of \u003cem\u003eBolboschoenetum maritimi, Phragmitetum australis\u003c/em\u003e associations. In the rivers mouths of the Mezen Bay and the Cheshskaya Bay, brackish marshes with communities of the \u003cem\u003eAlopecuretum arundinacei\u003c/em\u003e association are located on vast territories in the river estuaries heads.\u003c/p\u003e \u003cp\u003eSalt lakes are home to the communities of the association \u003cem\u003eHippuridetum tetraphyllae\u003c/em\u003e, lower littoral to those of \u003cem\u003eRuppietum maritimae\u003c/em\u003e and upper sublittoral to \u003cem\u003eZosteretum maritimae\u003c/em\u003e. The narrow tidal flats in the headwater regions of the estuaries are covered with large sedge communities of the associations \u003cem\u003eCaricetum aquatilis\u003c/em\u003e and \u003cem\u003eCaricetum acutae\u003c/em\u003e.\u003c/p\u003e \u003cp\u003eIt is demonstrated, that the salt marshes communities dominated by obligate halophytes are stenotopic in terms of salinity. On the contrary, the brackish marshes communities covered with facultative halophytes and salinity-tolerant glycophytes are more eurytopic regarding the he salinity factor.\u003c/p\u003e \u003cp\u003eThe conducted research expands adds up to the information about the halophytic vegetation of the coasts of the White Sea and the Cheshskaya Bay. The azonal coastal vegetation includes rather rare communities that are very vulnerable to natural and anthropogenic changes in the abiotic environment, which requires the development of biomonitoring of their condition. Monitoring of the vulnerable phytocenoses must be carried out annually in the rivers\u0026rsquo; mouths where marshes are formed. Many communities of the White Sea coast are rare, such is the association of \u003cem\u003eRuppietum maritimae\u003c/em\u003e, which requires their protection measures development, that is the annual monitoring of the dominant species \u003cem\u003eRuppia maritima\u003c/em\u003e population state, included in the bio-surveillance of the Red Book of the Arkhangelsk Region (2020).\u003c/p\u003e \u003cp\u003eThe technique of metric multidimensional scaling allows differentiating the biotopes with similar vegetation cover occurring on the accumulative shores. This approach can be applied to any marine coast, be it the Barents or the White Sea coast in the northern sector of the European continent, or the North or Baltic Sea that wash Central, Western and Northern Europe, since they are home to homogeneous biotopes. The structure and species composition of phytocenoses belonging to different types of biotopes reveal similarities and differences as to some of their elements and in the first place species composition. The salt and brackish marshes are often home to same species of halophytes and glycophytes, which are found even on beaches. This similarity indicates the unity of the accumulative shores in terms of vegetation, including species in the tidal zone, which form one single phytocenotic complex comprising the coastal halophytic vegetation. At the same time, given the biotope-specific dominant coastal species, there are certain differences.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eFunding\u0026nbsp;\u003c/strong\u003eThe work was carried out within the framework of the state task topic No. FMWE-2024-0020/\u0026quot;Sedimentation in modern and ancient oceans - dispersed sediment and bottom sediments as geologic archives of climate change and natural systems in key areas of the World Ocean, Russian seas and the sea-land boundary region\u0026quot;.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eData availability\u003c/strong\u003e All data generated or analyzed during this study are included in this published article and its supplementary materials.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCode availability.\u0026nbsp;\u003c/strong\u003eNot applicable.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConflict of interest\u0026nbsp;\u003c/strong\u003eThe authors declare no competing interests.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eEthical approval\u0026nbsp;\u003c/strong\u003eThe study was conducted in accordance with the ethical guidelines for wildlife research, and all necessary permissions were obtained from relevant authorities.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAcknowledgements\u0026nbsp;\u003c/strong\u003eThe work at the mouth of the Keret River in the Kandalaksha Bay was supported by the Botany and Plant Physiology Department of Petrozavodsk State University. The authors express their gratitude for financial support in conducting research by the All-Russian public organization \u0026quot;Russian Geographical Society\u0026quot;. \u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthors\u0026apos; contribution\u003c/strong\u003e: M. D.: Expeditionary research, Formal analysis, writing - initial draft, data acquisition and processing. L. A.: research, formal analysis, data processing. P. T.: formal analysis, data processing, writing - editing. V. A.: data processing, preparation of ordination methodology, formal analysis. L. S.: writing - initial draft. \u0026nbsp;M. I.: expedition research, writing - initial draft. \u0026nbsp; M. N.: text checking, text conceptualization.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eAdam P. (1993) Saltmarsh Ecology. Cambridge University Press. 476 p.\u003c/li\u003e\n\u003cli\u003eAlexandrova V.D. (1969) Classification of vegetation. 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(1984) Meadows of the Kovdsky Peninsula and Veliky Island. Botanical research in the reserves of the RSFSR. M., 50-66.\u003c/li\u003e\n\u003cli\u003eVekhov N.V. (1992) Zostera marina L. of the White Sea. Moscow: Publishing House of Moscow State University. 143 p.\u003c/li\u003e\n\u003cli\u003eWong M.C., Vercaemer B.M., Griffiths G. (2021) Response and recovery of eelgrass (Zostera marina) to chronic and episodic light disturbance. Estuaries and Coasts. 4 (2): 312-324.\u003c/li\u003e\n\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"polar-biology","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"pobi","sideBox":"Learn more about [Polar Biology](http://link.springer.com/journal/300)","snPcode":"300","submissionUrl":"https://submission.nature.com/new-submission/300/3","title":"Polar Biology","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false},"keywords":"biotopes, halophyte vegetation, marshes, salinity, pH","lastPublishedDoi":"10.21203/rs.3.rs-6564393/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-6564393/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eThe halophytic vegetation of the White and Barents Seas coasts of the Arctic Ocean is diverse, since it is formed under heterogeneous conditions under the influence of the ocean and land. Currently, little is known about the distribution of phytocenoses in saline biotopes on the White and Barents Seas coasts. The obtained picture of the halophyte vegetation structure will help to understand the patterns of coastal phytocenoses distribution in the biotopes of the White and Barents Seas coasts. From the standpoint of the ecological-phytocenotic approach, 40 associations were identified on the coasts based on the similarity of the structure and composition of plant communities. Vegetation ordination, built by the metric scaling method, shows the correspondence of plant communities to certain types of biotopes: salt marshes, brackish marshes, beaches and dunes, saline lagoon lakes, tidal flats at the heads of estuaries. In biotopes of various types, halophytic vegetation phytocenoses are formed, different in composition and structure. The paper employs ordination analysis to provide first-ever classification of brackish marshes into hygrophytic and hygromesophytic (grass-rush) groups, thus enriching the overall classification of marsh biocenoses.\u003c/p\u003e \u003cp\u003eThe biotopes of salt marshes are distinguished by the greatest phytocenotic diversity, with 21 associations of seaside vegetation identified. The species composition and halophyte vegetation structure are similar in the biotopes of the arctic marshes of the Mezen Bay and the Cheshskaya Bay estuaries, but these communities differ significantly from the boreal-type marshes on the southeast coast of the Dvina Bay and Onega Bay. The plants living conditions of different ecological groups in the sea coasts communities are not the same. Obligate halophytes develop in stable water salinity and pH conditions. Facultative halophytes are able to live in environments with wide pH and salinity variability.\u003c/p\u003e","manuscriptTitle":"Coastal Vegetation in the Biotopes of the Estuaries of the White Sea and the Cheshskaya Bay of the Barents Sea","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-05-21 15:36:23","doi":"10.21203/rs.3.rs-6564393/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2026-02-06T15:17:43+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-06-09T11:43:29+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"13083425246385454428047508522811419782","date":"2025-05-20T12:11:33+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2025-05-19T11:20:06+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2025-05-19T10:04:34+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2025-04-30T13:41:56+00:00","index":"","fulltext":""},{"type":"submitted","content":"Polar Biology","date":"2025-04-30T11:01:47+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"polar-biology","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"pobi","sideBox":"Learn more about [Polar Biology](http://link.springer.com/journal/300)","snPcode":"300","submissionUrl":"https://submission.nature.com/new-submission/300/3","title":"Polar Biology","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false}}],"origin":"","ownerIdentity":"476ff5c9-3bb9-408a-9a72-55e09748f48d","owner":[],"postedDate":"May 21st, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"under-review","subjectAreas":[],"tags":[],"updatedAt":"2026-05-16T16:24:18+00:00","versionOfRecord":[],"versionCreatedAt":"2025-05-21 15:36:23","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-6564393","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-6564393","identity":"rs-6564393","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}