The Diversity of Russian Estuaries and Lagoons Exposed to Human Influence

Lagoons and lagoon coasts are widely spread along the shores of the World Ocean (9.2 % of the total length of the coastal line). Modern world economic, climatic and geopolitical processes create a need for comprehensive study of the Russian seas and coastal areas of strategic importance. The physical and geographic features of lagoons – their relative shallowness, protection from storm surges from the open sea, the large daily and seasonal variability of hydrodynamic and hydrochemical parameters, and high biological productivity – allow us to consider them as unique natural objects. The main definitions of lagoons in the Russian seas, their classification, and time evolution are presented in this chapter.

The seas of the Arctic (Barents Sea, White Sea, Kara Sea, Laptev Sea, East-Siberian Sea, Chukchi Sea) wash over Russian territory from the North. Almost 70 % of Russian territory falls within the Arctic Ocean basin. Despite the necessity of monitoring instances of natural and technogenic changes in the Arctic, many segments of the Arctic coast are still “blank spots” for researchers. The main reason for the poor knowledge in regard to this region is its inaccessibility. Its lagoons and estuaries are among the most difficult for the study of natural geosystems, each of them distinguished by both natural features and their response to changes in external conditions.

The variations of accumulative shores (lagoon, delta) are widely spread within the Barents and Laptev Seas. They form a great many lagoons. The biggest estuaries are the Kola Gulf, situated near the city of Murmansk, and the Khatanga and Anabar estuaries. There are not that many full scale lagoons along the coasts of the Kara Sea, a fact which is related to the geological structure of the shores, the peculiarities of which do not facilitate the development of accumulative bodies. But the largest estuaries of the Russia Arctic coast are the estuaries of the Kara Sea: Obskaya Guba, Taz Guba, Yenisey Gulf, Baidaratskaya Guba and Gydanska Guba. A characteristic peculiarity of the East Siberian Sea is a long extension of the accumulative coasts (about 40 %), especially on the islands. The accumulative-lagoon systems are distinguished for their peculiar internal partition into a number of round basins. Accumulative bay-bars separating the shallow lagoons from the Chukchi Sea extend parallel to the continental coast over hundreds of kilometers. The bay-bar of the Tenkergynpilgyn Lagoon is approximately 100 km long, and the length of the Kuvetpilchin Lagoon exceeds 50 km. The abundance of coastal accumulative structures and the lagoons that they form is a consequence of the geological structure of the adjacent coast and the topography of the submarine slope.

The major portion of the lagoons of the Russian Arctic coast is formed by accumulative bodies: bars, bay-bars, and spits. The influence of the changes in external conditions on the accumulative coastal bodies is different depending on their type of feeding and formation. Over recent decades, changes in all climatic parameters have been observed throughout the planet, especially in the Arctic regions. This natural global process inevitably influences the state of geosystems along the entire Arctic coast, including lagoons and estuaries. At present, it is impossible to say with certainty how large the positive or negative consequences of the Arctic’s climate changes will be. Human activities in the Arctic almost always have a negative impact upon the environment. Environmental protection measures may decrease this impact but are not capable of preventing it in full measure. Fortunately, the severe natural conditions do not allow for a large scale development of the coast, as has happened in more favorable regions.

Lagoons and estuaries are widespread along the coasts of the Far Eastern Seas. These lagoons and estuaries became objects of active research only in the second half of the twentieth century.

On the shores of the Japan, Okhotsk and Bering Seas are located 240 lagoons, ranging in size from 1 to 1000 km². A large portion of them are shallow lagoons, with depths of up to 5–6 m. Deep lagoons, with a depth of over 20 m, occur on the coasts of fjords.

For the last 25 years, the research has been complex and comprehensive. It involved studying the hydrological, hydrochemical and ice regimes of the lagoons, as well as the mechanical and chemical composition of bottom sediments, bottom biological communities, etc.

Estuaries can be divided into three types based on human impact: (1) – estuaries and lagoons that are still relatively pristine; (2) – estuaries and lagoons in the process of being degraded; and (3) – estuaries and lagoons that bore the full pressure of historical developments. For type (1), the case studies focus on the Nabyl Lagoon; for type (2), the case studies focus on the Amur Liman and the Busse Lagoon; for type (3), the case studies focus on Peter the Great Bay.

The major economic activities in these regions include oil and gas exploration, and the harvesting and processing of fish and marine products. Lagoons, estuaries, and limans play a significant role in transportation infrastructure: ports, channels, harbors, etc.

The length of the Russian Caucasus coast of the Black Sea is approximately 400 km. The prevalence of abrasion coasts and the deficiency of sediments and accumulative forms are characteristic of the Russian Black Sea. This coast has only two significant lagoon localities: the Black Sea Kuban limans (Kiziltashsky group) and the Imeretinskaya lowland, along with some small lagoons. The Kiziltashsky group is included in the lagoon system of the Kuban River delta and separated from the Black Sea by the Anapa bay-bar. The history of the formation of the geosystems of this lagoon group and the Anapa bay-bar are closely interrelated. In middle of the XXth century, the runoff of the Kuban waters into the Kiziltashsky lagoon group completely stopped, and since the natural restoration of the Kuban River, run-off to the lagoons is nearly impossible, the further development of the lagoon ecosystem depending completely on the state of the accumulative body of the Anapa bay-bar. The Imeretinskaya lagoons are located between the Mzymta and Psou Rivers. After 2008, during construction for the Sochi Olympic Games of 2014, all the lagoons were irreversibly changed and their existence as natural water reservoirs was almost negated. The modern hydrographic network of the Imeretinskaya Lowland is represented by a system of melioration irrigation-drainage channels and semi-artificial ponds. Unique basins in the zone of the land and sea border, formed as a result of landslide processes, are located at the coast of the Russian Black Sea as well. Black Sea lagoons are used as areas for recreation and fish farming. Thus, there are lagoons of different types on the coast, the structure and intensity of the natural processes determining their stability varying considerably. Nevertheless, there are a number of natural threats to the stability of the lagoon coasts, and they are common for lagoons of different type and size. At present, out of the consequences of the sea level rise, changes in the surface run-off volume and degradation of accumulative features resulting from the inflow of sediments are the most apparent.

The Sea of Azov is one of the smallest on the planet. Its surface area is 39.1 thousand km² and the average depth is about 7.4 m. The total length of the seashores along the Russian part of the Sea of Azov is about 500 km. The majority of the population of the Krasnodar region lives in the coastal zone of the Sea of Azov. This area includes important federal and international communications, ports, industrial and civil establishments. A comprehensive study of contemporary seaside processes has allowed for identifying four main types of coastal development: abrasion (representing two types), accumulation and stable. In general, the following natural processes defining the state and dynamics of the region’s coasts can be highlighted: abrasion processes, sea level fluctuations, changes in wind-wave regime parameters, and fluctuation in the volume of biogenic materials.

Lagoons, like other water bodies of land-to-sea interface, have long attracted the attention of scholars and experts because of their abundance in the littoral area of the Sea of Azov, their natural uniqueness and their high resource potential. Historically, the majority of the land-to-sea interface water bodies of the Sea of Azov are called “limans”. There are three main lagoon groups: the Azov-Kuban limans, the East-Azov limans, the lagoons of the Kerch Strait and many small lagoon reservoirs. As a rule, these are brackish-water reservoirs separated from the Sea of Azov by accumulative forms. Until the middle of the nineteenth century, the evolution of the Azov lagoons was determined by natural factors, as the population of the coastal area was very small and the agriculture was undeveloped. Now, the role of man’s impact is significant. Water bodies are used for irrigation and as areas for recreation, hunting, fishing and fish farming. It has also proved to have significant value for fisheries. In recent decades, a significant reduction in river run-off, used for irrigation farming, resulted in the salinization of lagoons, causing the degradation of species of flora and fauna and a general reduction in the ecosystems’ productivity, especially the fish capacity of the water basin. The Azov lagoons occupy an important place in the reproduction of the local semi-aquatic and water birds, as well as for the migratory routes of the many birds that run through this territory. The Azov lagoons are unique coastal systems. A large part of the Azov lagoons is included on the Ramsar Convention list of wetlands of international importance.

The Curonian and Vistula Lagoons should be considered to be a part of one natural hydraulic system, as they are connected via two branches of the Prgolya River (the Pregolya River proper and the Deyma branch). The catchment upstream of the point of bifurcation of the Pregolya River into these two branches belongs to both lagoons and comprises 14 % and 57 % of the entire catchments of the Curonian and Vistula Lagoons, respectively. Approximately 36–40 % and 60–64 % of the run-off of the Pregolya River discharges into the Curonian and Vistula Lagoons, respectively.

While the Curonian Lagoon has maintained the same environmental conditions over the ages, the Vistula Lagoon experienced considerable anthropogenic modification at the end of the nineteenth century, evolving from a freshwater running coastal lake to an estuarine lagoon with predominant marine influence.

Nowadays, changes in the physical characteristics of both lagoons are mostly expressed in water level and temperature rise. Details of the annual hydraulic cycle and the spatial patterns of salinity, temperature and bottom sediment variability are discussed for the Vistula Lagoon.

Both lagoons are transboundary, belonging to countries with different water management systems (Russia is a non-EU country, Lithuania and Poland are EU countries). Both lagoons are most intensively used for fishing, but the Vistula Lagoon has many other significant purposes as well, especially navigation. As a consequence, there exist numerous potential conflicts between environmental and anthropogenic use, as well as other types of use, of the lagoon area.

The chapter is devoted to the geological development, hydrology, biology and environmental status of Neva Bay – the easternmost and shallowest part of the Gulf of Finland (the Baltic Sea). After the construction of the St. Petersburg Protection Facility, which separates Neva Bay from the Gulf of Finland, it was deliberately transformed into a technogenic lagoon. Neva Bay and its coastal zone were formed during the late Pleistocene deglaciation and Holocene sea-level fluctuations. The last very important event in Holocene geological history was the Neva River’s onset from Lake Ladoga. Since the founding of St. Petersburg in 1703, Neva Bay has been influenced by increasing anthropogenic impact. Intense dredging and dumping caused a transformation of the bottom relief and sediments. The silty clay mud of the sedimentation basins provides information about “pollution history” of Neva Bay as a result of the rapid development of industry in St. Petersburg in the twentieth century. The Neva Bay ecosystem has certain unique features. Despite intensive traffic, dredging and dumping, leading to the destruction of aquatic habitats, the living planktonic and benthic communities are characterized by their regenerative ability.

The White Sea is Russia’s inland sea. The chapter contains a description of a new model for structural organization of the White Sea as an estuarine system and characteristics of the main factors forming the sea’s regime. Following an overall typification of the coast, the chapter presents general characteristics of the coastal structure, landscapes and biological features, as well as the development of morphodynamic and lithodynamic processes. A description is provided on the morphology of the landscape and coastal marine areas, including lagoons and the estuarine coast. The data on unique natural objects, rare and endangered species and anthropogenic impacts on the White Sea coasts are discussed.

This paper gives an overview of the eight chapters of the book “The Diversity of Russian Estuaries and Lagoons Exposed to Human Influence” edited by R. Kosyan in the collection “Estuaries of the World”. The book gives a comprehensive review of the current state of knowledge of the estuaries and marine coastal lagoons of Russia, identifying the most urgent problems concerning the management of natural resources and ecosystem services they provide. The analysis of ecological, geographical and socio-economic aspects governing the evolution of these ecosystems demonstrates that the natural features which characterize them are not currently adequately addressed. The economic development of coastal areas in Russia does not sufficiently take into account the structure and functioning of these complex natural systems. There is an urgent need for recommendations as to integrated planning and balancing of economic activities taking place in coastal municipalities and regions of the Russian Federation that include such unique coastal systems as lagoons, estuaries and limans.