The Genesis and Evolution of the Caspian Sea Lagoons as Avifauna Refuges at the Transboundary Scale

Evgeny Viktorovich Vilkov

doi:10.4236/ojms.2016.61011

Abstract

The article summarizes 34 years (1980-2014) of the original observations of the genesis and evolution stages of the Caspian lagoons. A model of the formation and evolution of the coastal lagoons has been worked out. It can be applied to the modelling of the global geoecological scenario along all the world’s coasts characterized by a steady transgression of their marine areas. The lagoons had been formed in a “bottleneck”, a narrow migration corridor, traversed by the largest migration route of trans-Palearctic species in Russia. This route is part of the West Siberian-East African migration range. Year round bird censuses (n = 746) were taken by the author in 1995-2014 along two key routes in the regions of Turalinskaya and Sulakskaya lagoons of Daghestan (the western coast of the Middle Caspian Sea). The meridional orientation of lagoons, location of the migration trajectory and a wide range of habitats in the study area contribute to the preservation of 294 Eurasian bird species. After formation of the lagoons, the breeding avifauna of the Caspian Sea Region of Central Daghestan has added 32 taxa. Among the species recorded at the lagoons, 50 are included in the IUCN Red List, Red Data Books of Russia and Daghestan. The reconstruction analysis of the migration trajectory compiled according to the data of the Russian Bird Ringing Centre allowed us to determine the population distribution geography for the birds regularly migrating along the western coast of the Caspian Sea and refine borders of theWest Siberian-East African migration range. Thus, according to the information received, the current migratory range should be greatly extended to cover the area from the British Isles in the West Palearctic to Lake Baikal in the east, including the extreme west and south of Africa.

Highlights

In the context of global warming, accompanied by a tendentious rise of the World Ocean [1] and increase in the level of some seas including the Caspian Sea, the conservation issues of coastal wetland ecosystems and waterbirds have become relevant, especially since the waterbird abundance has markedly reduced in recent years [2]-[5]
Starting from 1979 the Caspian level has been rapidly rising [18], and between the late 1970s and mid 1990s the water surface of the sea increased from 370 to 452 km2 [19] (Figure 3). It resulted in structural geoecological changes in some areas of the Daghestanian coast in the Middle Caspian Region and led to the formation of new aquatic ecosystems—brackish lagoons [13], among which Sulakskaya and Turalinskaya became the most valuable for birds (Figure 2)
A formation mechanism of coastal barriers and, subsequently, lagoons is based on the ratio between the gradient of underwater slope (USL) and the gradient of adjacent land area [15]

Summary

Introduction

In the context of global warming, accompanied by a tendentious rise of the World Ocean [1] and increase in the level of some seas including the Caspian Sea, the conservation issues of coastal wetland ecosystems and waterbirds have become relevant, especially since the waterbird abundance has markedly reduced in recent years [2]-[5]. Western Coast of the Caspian Sea, Daghestan, Lagoon Evolution, Conservation of Eurasian Birds

Results

Conclusion